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Archive for the ‘Epidemiology’ Category

Chagas Disease

by Dr. Jaclynn Moskow

Trypanosoma cruzi parasite, 3D illustration. A protozoan that causes Chagas' disease transmitted to humans by the bite of triatomine bug
Trypanosoma cruzi parasite, the etiologic agent of Chagas disease

 

In 1909, Brazilian physician Carlos Chagas learned of a local phenomenon in which blood-sucking insects were biting people on the face during sleep. On April 14, he dissected one such insect and found parasitic euglenoids living inside of it (1). Dr. Chagas named the parasite Trypanosoma cruzi (T. cruzi) and, in this moment, discovered both the causative agent and vector of “Chagas Disease.”

On April 14, 2021, we recognize the second annual World Chagas Disease Day (2). Chagas disease, also known as American Trypanosomiasis, is endemic to Latin America. It can lead to severe cardiac, neurologic, and gastrointestinal disease  – and in some cases is fatal, causing about 12,000 deaths each year (3).

The Chagas disease represents the third-largest tropical disease burden worldwide, after malaria and schistosomiasis (4). It has likely been with us for thousands of years, as T. cruzi DNA has been recovered from ancient mummies and bone fragments (1).

Transmission

Triatomine bugs, also known as “kissing bugs”, “cone-nosed bugs”, or “bloodsuckers”, are the vectors for Chagas disease. They acquire T. cruzi after biting infected animals or humans and transmit the parasite to others through their feces. There are over 150 species of domestic and wild animals that serve as reservoirs for Chagas disease (5), including dogs, cats, pigs, rabbits, raccoons, rats, bats, armadillos, and monkeys.

 

The kissing bug. Blood sucker, infection is known as Chagas disease.
‘Kissing bug’,  vector of Chagas disease

 

Triatomine bugs are commonly found in rural areas, in houses made from materials such as mud, adobe, straw, and palm thatch (6). They feed at night. If they defecate on an individual and T. cruzi gains access to the body via a mucus membrane or break in the skin, the transmission of Chagas disease may occur.

Vertical transmission of Chagas disease is possible during pregnancy. Chagas disease can also be transmitted via blood transfusion and organ transplantation, and there is some evidence that it may be transmitted through sex and in rare instances through consumption of game meat. It can also be acquired by consuming food or water contaminated with insect remains (4).

 

Clinical Presentation

The incubation period for Chagas disease depends upon the mode of transmission. Vectorially transmitted cases usually manifest in one-to-two weeks, while orally transmitted cases may take up to 3 weeks – and transfusion-based cases up to 120 days (5).

Chagas disease has an acute and chronic phase. The acute phase is often asymptomatic or mild in nature and usually resolves spontaneously (5). The acute phase may begin with the development of a “chagoma” – an indurated area of erythema and swelling with local lymph node involvement (7). “Romana’s sign” consists of painless edema of the eyelids and periocular tissues (resulting from conjunctival inoculation) and is usually unilateral. Patients in the acute phase may develop fever, malaise, and anorexia. Generalized lymphadenopathy and mild hepatosplenomegaly may be present. Rarely, meningoencephalitis or severe myocarditis with arrhythmias and heart failure may occur.

10% to 30% of acute infections will progress to chronic disease. Chronic disease may present years or decades after the initial infection. Cardiac manifestations include arrhythmias, thromboembolism, and cardiomyopathy. Arrhythmias may present as episodes of vertigo, syncope, or seizures. Congestive heart failure may develop, leading to death. Cerebral disease can also occur and is characterized by headache, seizures, focal neurological deficits, and evidence of ischemia and infarct. Gastrointestinal manifestations include megaesophagus and megacolon. Dysfunction of the urinary bladder is also reported. Chagas disease has an overall case-fatality rate of 10% (7).

Patients with chronic Chagas disease who become immunosuppressed may experience a reactivation of the infection. In individuals with concurrent HIV/AIDS and Chagas disease, the central nervous system is the most commonly affected site, and space-occupying lesions often occur. (8).

 

Diagnosis and Treatment

Chagas disease may be diagnosed through visualization of protozoa in blood or tissue, serology, xenodiagnosis, or PCR. The anti-parasitic medications Nifurtimox or Benznidazole can be used for treatment. Treatment is curative in approximately 50-80% of acute-phase cases, and 20-60% of chronic phase cases (9). Treatment is curative in greater than 90% of congenital cases when given within the first year of life (10). Treatment of pregnant women is not recommended (11).

Prevalence 

Vector-borne transmission of Chagas disease only occurs in the Americas. Approximately 121 million individuals are at risk in Central and South America and Mexico. If you have a GIDEON account, click here to explore our Chagas disease outbreak map. An estimated 8 million people are currently infected (12).  

Vector-borne transmission of Chagas disease is exceedingly rare in the United States, with 28 cases documented between 1955 and 2015 (13). About 300,000 people are currently living in the United States with Chagas disease that was acquired in Latin America (14). In Europe, the prevalence of T. cruzi infection among Latin American migrants is approximately 6% (4).

In 2007, two notable outbreaks occurred as the result of ingestion of sources contaminated with T. cruzi. 166 cases occurred in Brazil from contaminated food and 128 cases in Venezuela from contaminated juice (4). 

 

Prevention

Vector-control programs centered around the widespread use of insecticides have led to some success in decreasing the prevalence of Chagas disease. This progress, however, has been recently complicated by the emergence of insecticide-resistant vectors.

 

Falling death rates of Chagas disease (Trypanosomiasis – American), 1990 – 2016

 

Trypanosomiasis – American is otherwise known as Chagas disease

 

Individuals living in endemic areas can decrease their risk of contracting the disease by completing home improvement projects aimed at disrupting triatomine bug nests. These nests are commonly found beneath porches, between rocky surfaces, in wood/brush piles, rodent burrows, and chicken coops (15). Individuals traveling to endemic areas can decrease their risk of contracting the disease by applying insect repellent, wearing protective clothing, and using bed nets.

The screening of blood products for Chagas disease is another important prevention strategy. In most endemic countries, all blood donations are tested for T. cruzi antibodies. In countries in which cases are imported, screening strategies vary (16, 17). In the United States, all first-time blood donors are tested. In Canada, the UK, and Spain, only donors considered “at-risk” are tested (such as those who previously lived in, or recently traveled to, Latin America). In Sweden, individuals who lived in endemic countries for more than five years are precluded from donating blood, while in Japan, only individuals with a known history of Chagas disease are excluded. In China, blood donors are not currently screened for Chagas disease.

Recently, a new surveillance system for Chagas disease has been implemented in some countries where malaria is also endemic; microscopy technicians have been trained to identify T. cruzi in malaria films (18).

 

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References 

(1) D. Steverding, “The history of Chagas disease”, Parasites & Vectors, vol. 7, no. 1, p. 317, 2014. Available: 10.1186/1756-3305-7-317

(2) “World Chagas Disease Day: raising awareness of neglected tropical diseases”, World Health Organization, 2019. [Online]. Available: https://www.who.int/neglected_diseases/news/world-Chagas-day-approved/en/

(3) B. Lee, K. Bacon, M. Bottazzi and P. Hotez, “Global economic burden of Chagas disease: a computational simulation model”, The Lancet Infectious Diseases, vol. 13, no. 4, pp. 342-348, 2013. Available: 10.1016/s1473-3099(13)70002-1 

(4) “Trypanosomiasis – American Worldwide Distribution”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/trypanosomiasis-american-12460/worldwide

(5) A. Rassi, A. Rassi and J. Marin-Neto, “Chagas disease”, The Lancet, vol. 375, no. 9723, pp. 1388-1402, 2010. Available: 10.1016/s0140-6736(10)60061-x

(6) “Parasites – American Trypanosomiasis (also known as Chagas Disease): Detailed FAQs”, Centers for Disease Control and Prevention, Global Health, Division of Parasitic Diseases and Malaria, 2021. [Online]. Available: https://www.cdc.gov/parasites/chagas/gen_info/detailed.html#intro

(7) “Trypanosomiasis – American”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/trypanosomiasis-american-12460

(8) A. Vaidian, L. Weiss, and H. Tanowitz, “Chagas’ disease and AIDS”, Kinetoplastid Biol Dis, vol. 3, no. 1, p.2, 2004. Available: 10.1186/1475-9292-3-2

(9) J. Guarner, “Chagas disease as example of a reemerging parasite”, Seminars in Diagnostic Pathology, vol. 36, no. 3, pp. 164-169, 2019. Available: 10.1053/j.semdp.2019.04.008

(10) F. Machado et al., “Chagas Heart Disease”, Cardiology in Review, vol. 20, no. 2, pp. 53-65, 2012. Available: 10.1097/crd.0b013e31823efde2

(11) E. Howard, P. Buekens and Y. Carlier, “Current treatment guidelines for Trypanosoma cruzi infection in pregnant women and infants”, International Journal of Antimicrobial Agents, vol. 39, no. 5, pp. 451-452, 2012. Available: 10.1016/j.ijantimicag.2012.01.014

(12) “Chagas disease (American trypanosomiasis): Epidemiology”, World Health Organization, 2021. [Online]. Available: https://www.who.int/chagas/epidemiology/en/

(13) S. Montgomery, M. Parise, E. Dotson and S. Bialek, “What Do We Know About Chagas Disease in the United States?”, The American Journal of Tropical Medicine and Hygiene, vol. 95, no. 6, pp. 1225-1227, 2016. Available: 10.4269/ajtmh.16-0213

(14) “Parasites – American Trypanosomiasis (also known as Chagas Disease): Epidemiology & Risk Factors”, Centers for Disease Control and Prevention, Global Health, Division of Parasitic Diseases and Malaria, 2019. [Online]. Available: https://www.cdc.gov/parasites/chagas/epi.html

(15) “Parasites – American Trypanosomiasis (also known as Chagas Disease): Triatomine Bug FAQs”, Centers for Disease Control and Prevention, Global Health, Division of Parasitic Diseases and Malaria, 2020. [Online]. Available: https://www.cdc.gov/parasites/chagas/gen_info/vectors/index.html

(16) A. Angheben et al.,”Chagas disease and transfusion medicine: a perspective from non-endemic countries”, Blood Transfus, vol. 13, no. 4, pp. 40-50, 2015. Available: 10.2450/2015.0040-15

(17) V. Mangano, M. Prato, A. Marvelli, G. Moscato and F. Bruschi, “Screening of at‐risk blood donors for Chagas disease in non‐endemic countries: Lessons from a 2‐year experience in Tuscany, Italy”, Transfusion Medicine, vol. 31, no. 1, pp. 63-68, 2020. Available: 10.1111/tme.12741 

(18) “Chagas disease (American trypanosomiasis): Prevention of Chagas Disease”, World Health Organization, 2021. [Online]. Available: https://www.who.int/chagas/disease/prevention/en/

Occupational Infectious Diseases

by Dr. Jaclynn Moskow

Occupational health: Manufacturer working at storage tanks in brewery

 

In recognition of World Health Day 2021, which falls on April 7, the WHO points out that “some people are able to live healthier lives and have better access to health services than others – entirely due to the conditions in which they are born, grow, live, work, and age.”

Many of us spend a significant portion of our lives engaged in work. Unfortunately, certain working conditions put us at increased risk of poor health. For example, some occupations involve repeated exposure to respiratory irritants and carcinogens, while others are associated with musculoskeletal injury or hearing loss. Many professions put workers at risk of contracting an infectious disease.

Textbook of Occupational Medicine Practice (1) outlines five primary modes of transmission for occupational infections:

  1. Contact with animals and animal products (zoonoses)
  2. Exposure to vectors 
  3. Care of patients 
  4. Environmental sources, exposure to soils 
  5. Occupational skin infections

 

Occupational Zoonoses

Farmer with cow

Individuals who work with animals and animal products are at risk of contracting zoonotic diseases. Such occupations include farmworkers, ranch workers, butchers, veterinary workers, and zoo workers. There are currently over 200 recognized zoonoses (2).

Brucellosis is a zoonotic infectious disease caused by Brucella spp. Reservoirs for Brucella include pigs, cattle, sheep, goats, dogs, coyotes, and caribou. Brucellosis can be acquired via direct contact with these animals, or by processing their meat. Symptoms include prolonged fever, hepatosplenomegaly, lymphadenopathy, arthritis, and osteomyelitis (3). A study of occupationally acquired Brucella in Russia found that factors increasing the risk of infection include lack of awareness amongst workers regarding the disease and absence of regular inspections of working conditions (4).

Individuals who work with cats are at increased risk of acquiring bartonellosis, also known as “cat scratch disease.” As the name implies, the disease is caused by species of Bartonella and transmitted via cat scratches. Clinical manifestations include tender suppurative regional adenopathy and fever. Occasionally, systemic infection occurs involving such sites as the liver, brain, endocardium, and bones (5). A recent study of veterinary personnel detected Bartonella in 28% of subjects, compared to 0% of a control group (6).

A review of the incidences of campylobacteriosis and cryptosporidiosis in Nebraska between 2005-2015 identified occupational animal exposure as the cause in 16.6% and 8.7% of cases, respectively (7). Most of these cases were acquired by farmers, ranchers, and those working in animal slaughter and processing facilities; and the most common animal source was determined to be cattle. Additional occupational zoonotic infectious diseases include salmonellosis, Escherichia coli O157 infection, and Q-fever.

 

Occupational Infections Acquired Via Exposure to Vectors

Woman digging hole with shovel to plant saplings in forest. Forester planting new small trees in deforested area. Vector-borne diseases are occupational hazards for forestry workers.

Individuals working in areas infested with ticks, fleas, and mites are at an increased risk for infectious diseases carried by these arthropods. Occupations at risk include agricultural workers, forestry workers, military personnel, veterinary workers, and pest control workers.

Diseases that may be spread to workers via tick bites include Lyme disease, babesiosis, ehrlichiosis, Colorado tick fever, Rocky Mountain spotted fever, tularemia, and Powassan virus encephalitis. In the United States, Lyme disease is the most common tick-borne illness. It is caused by Borrelia spp. and characterized by the presence of erythema migrans, neurological, musculoskeletal, and cardiac manifestations.

Individuals working around fleas may acquire flea-borne (murine) typhus, caused by Rickettsia typhi, or Plague caused by Yersinia pestis. Additionally, exposure to mites could lead to the development of rickettsialpox, caused by Rickettsia akari, or scrub typhus, caused by Orientia spp.

 

Occupational Infections Acquired Via Care of Patients

Female nurse tying surgical mask in operation theater

 

Caring for patients while working in hospitals, ambulatory clinics, diagnostic laboratories, nursing homes, and the home carries an increased risk for several infectious diseases.

Each year, healthcare workers experience approximately 600,000–800,000 exposures to HIV, hepatitis B, and hepatitis C (8). Exposures may occur via needle-stick injury or via blood and other bodily fluids which accidentally contact mucous membranes. Healthcare workers can decrease their risk of contracting bloodborne pathogens by adhering to universal precautions.

Airborne pathogens are also of concern to healthcare workers. Respiratory diseases that can be acquired while caring for patients include tuberculosis, influenza, and COVID-19. Healthcare workers are also at increased risk of contracting methicillin-resistant Staphylococcus aureus (MRSA). Approximately 4.6% of healthcare workers carry MRSA (9), compared to 1% of the general population (10).

Vaccinations recommended to healthcare workers to help prevent occupationally acquired infections include hepatitis B, MMR, and influenza. 

 

Occupational Infections Acquired Via Exposure to Soils

Close-up low section of woman standing with fork on dirt

Individuals engaged in plowing, digging, and excavating soil at work may be exposed to a variety of infections. Such occupations include construction and demolition work, oil and gas extraction, agriculture workers, landscaping, and archaeology.

Workers exposed to soils are at an increased risk of endemic mycoses, including histoplasmosis, coccidioidomycosis, paracoccidioidomycosis, and blastomycosis. These infections are generally acquired by inhaling fungal spores that become airborne as the soil is disrupted. An example of this occurred between 2011 and 2014 when an outbreak of coccidioidomycosis occurred among workers constructing solar power-generating facilities in San Luis Obispo County, California. A total of 44 cases were documented, including nine hospitalizations (11). 

The paradigm disease associated with soil contact is tetanus, caused by Clostridium tetani. Tetanus is acquired when bacterial spores found in soil are introduced to the body via a breach in the skin. Clinical manifestations of tetanus include trismus (lockjaw), facial spasm, opisthotonos, recurrent tonic spasms of skeletal muscle, and tachycardia. Tetanus has a case fatality rate of 10 to 40% (12). Tetanus cases can be prevented through vaccination…and the CDC reports that the efficacy of the tetanus vaccine is nearly 100% (13).

 

Occupational Skin Infections

Butchers may catch occupational skin infections by exposure to raw meat

There are a wide variety of professions in which occupational exposure to skin infections may occur. These include farmers, fisherman, butchers, veterinary workers, aquarium workers, swimming pool cleaners, healthcare workers, and salon workers. 

Many occupational skin infections result from exposure to animals and animal tissue. For example, farmers and butchers are at an increased risk of contracting cutaneous anthrax, caused by Bacillus anthracis. Cutaneous anthrax usually begins with pruritus at the affected site and is followed by a small, painless papule that progresses to a vesicle. The lesion erodes and becomes necrotic, and secondary vesicles are sometimes observed. Lymphadenopathy, fever, and headache may also occur. When left untreated, approximately 20% of cases are fatal (14).

Erysipeloid, caused by Erysipelothrix rhusiopathiae, can also occur when working with animals and animal tissues. The infection is characterized by rash, local pain, swelling, and occasionally fever. One report described an outbreak of erysipeloid amongst workers at a shoe factory (15). The source of the bacteria was determined to be raw leather.

Exposure to water is another common source of occupational skin infections. Fish tank granuloma, an infection caused by Mycobacterium marinum, is often acquired by aquarium workers. Fishermen are at risk of contracting Vibrio vulnificus infection through contact with contaminated ocean water or fish.

Other infections of the skin that can be acquired at work are caused by fungi. Examples include candidiasis, dermatophytosis, chromomycosis, and sporotrichosis. Scabies, a parasitic skin infestation caused by a mite, is often reported among healthcare workers, daycare workers, and correctional facility employees.

 

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References

(1) D. Koh and T. Aw, “Textbook of Occupational Medicine Practice”, 2017. Available: 10.1142/10298

(2) “Other Neglected Zoonotic Diseases”, World Health Organization, 2021. [Online]. Available: https://www.who.int/neglected_diseases/zoonoses/other_NZDs/en/

(3) “Brucellosis”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/brucellosis-10260

(4) A. Tarkhov,  et al., “The Working Conditions At Animal Farm Complexes of Workers With Occupational Brucellosis”, Med Tr Prom Ekol, vol. 5, pp. 5-9, 2012.

(5) “Bartonellosis – Cat Borne”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/bartonellosis-cat-borne-10320

(6) P. Lantos et al., “Detection of Bartonella Species in the Blood of Veterinarians and Veterinary Technicians: A Newly Recognized Occupational Hazard?”, Vector-Borne and Zoonotic Diseases, vol. 14, no. 8, pp. 563-570, 2014. Available: 10.1089/vbz.2013.1512

(7) C. Su, D. Stover, B. Buss, A. Carlson and S. Luckhaupt, “Occupational Animal Exposure Among Persons with Campylobacteriosis and Cryptosporidiosis — Nebraska, 2005–2015”, MMWR. Morbidity and Mortality Weekly Report, vol. 66, no. 36, pp. 955-958, 2017. Available: 10.15585/mmwr.mm6636a4

(8) N. Swanson, C. Ross and K. Fennelly, “Healthcare-related Infectious Diseases1”, Emerging Infectious Diseases, vol. 10, no. 11, pp. e3-e3, 2004. Available: 10.3201/eid1011.040622_03

(9) W. Albrich and S. Harbarth, “Health-care workers: source, vector, or victim of MRSA?”, The Lancet Infectious Diseases, vol. 8, no. 5, pp. 289-301, 2008. Available: 10.1016/s1473-3099(08)70097-5

(10) “MRSA and the Workplace”, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 2015. [Online]. Available: https://www.cdc.gov/niosh/topics/mrsa/default.html

(11) G. Sondermeyer Cooksey et al., “Dust Exposure and Coccidioidomycosis Prevention Among Solar Power Farm Construction Workers in California”, American Journal of Public Health, vol. 107, no. 8, pp. 1296-1303, 2017. Available: 10.2105/ajph.2017.303820

(12) “Tetanus”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/tetanus-12330

(13) “Tetanus”, Centers for Disease Control and Prevention, Epidemiology and Prevention of Vaccine-Preventable Diseases, 2008. Available: https://www.cdc.gov/vaccines/pubs/pinkbook/downloads/tetanus.pdf

(14) “Anthrax”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/anthrax-10100

(15) V Popugaĭlo VM, et al., “Erysipeloid as an occupational disease of workers in shoe enterprises”, Zh Mikrobiol Epidemiol Immunobiol, vol. 10, pp. 46-9, 1983.

World Tuberculosis Day 2021

by Dr. Jaclynn Moskow

Doctor with magnifier looking at bacteria in lungs. Tuberculosis, mycobacterium tuberculosis and world tuberculosis day concept on white background. Bright vibrant violet vector isolated illustration

Each year on March 24th, we recognize “World Tuberculosis Day” in an effort to build global awareness about the ongoing tuberculosis epidemic. Tuberculosis is an infectious disease caused by bacteria of the Mycobacterium tuberculosis complex, including Mycobacterium tuberculosis, Mycobacterium africanum, and Mycobacterium bovis (1). Worldwide, tuberculosis is the leading cause of death from an infectious agent (2).

“World Tuberculosis Day” occurs on March 24th as it was on this date, in 1884, that Dr. Robert Koch announced that he had discovered the causative agent of this disease (3).

 

Transmission

Tuberculosis is generally spread via the inhalation of droplet nuclei expelled by individuals with the active pulmonary or laryngeal disease. Less commonly, humans may also acquire tuberculosis from consuming unpasteurized dairy products. The incubation period of tuberculosis ranges from 4w-12w.

 

Clinical Manifestations

Clinical manifestations of tuberculosis vary depending on the site of mycobacterial proliferation (4). Most infections represent reactivation of a dormant focus in a lung and present with chronic fever, weight loss, nocturnal diaphoresis, and productive cough (5). Approximately 8% of patients with pulmonary tuberculosis will experience hemoptysis (6). Tuberculosis can also cause extrapulmonary disease in sites including the bone, joints, muscles, central nervous system, gastrointestinal system, hepatobiliary system, genitourinary system, eyes, breasts, and skin.

Individuals with latent tuberculosis infection (LTBI) do not experience symptoms but are carriers of the disease. They cannot spread the disease to others unless it becomes reactivated. The lifetime risk of reactivation for a person with documented LTBI is estimated to be 5–10% (7). Immunocompromised individuals are much more likely to experience tuberculosis reactivation.  

 

Diagnosis and Treatment

A definitive diagnosis of tuberculosis is made by the identification of the Mycobacterium tuberculosis complex in a clinical sample. Since the culture of these bacteria can be time-consuming, treatment may be initiated based on clinical suspicion alone. Tuberculosis skin tests and blood tests can be used to identify whether an individual has been infected, but cannot be used to distinguish between active and latent infections. Radiographic and other imaging techniques may also be useful in identifying patients, including those with asymptomatic active disease.

 

Mantoux test, positive result. Author: Grook da Oger.
Mantoux test, positive result. Author: Grook da Oger.

 

Typical pulmonary infection is treated with two months of Isoniazid, Rifampin, and Pyrazinamide (with Ethambutol pending results of susceptibility testing), followed by four months of Isoniazid and Rifampin alone. Treatment of multidrug-resistant tuberculosis generally includes the use of five drugs (including Pyrazinamide and/or Rifampin) for at least 6 months, followed by four drugs for 18-24 months (5).

Patients suspected of having active tuberculosis should be isolated, and healthcare personnel should observe relevant precautions.

The Centers for Disease Control and Prevention recommends treating individuals with latent tuberculosis that are at a high risk of progressing to an active infection. Included in the “high risk” designation are individuals with HIV/AIDS and other diseases that weaken the immune system, individuals who became infected with tuberculosis in the last two years, infants and young children, the elderly, and injecting drug users (8).

 

Prevalence 

In 2018, approximately 1.7 billion individuals were infected with Mycobacterium tuberculosis – roughly 23% of the world’s population (9). In 2019, approximately 10 million individuals experienced symptomatic tuberculosis, and approximately 1.4 million died as a result of the disease (10). Tuberculosis is found worldwide, but over 95% of cases and deaths occur in developing countries (10). Eight countries currently account for two-thirds of new tuberculosis cases: India, Indonesia, China, Philippines, Pakistan, Nigeria, Bangladesh, and South Africa (10). If you have a GIDEON account, click here to explore our tuberculosis outbreak map.

 

Tuberculosis cases and rates Worldwide, 1965 – today

Worldwide Tuberculosis cases and rates, 1965 - today

Vaccination 

Currently, Bacille Calmette-Guerin (BCG) vaccine remains the only licensed vaccine for the prevention of tuberculosis. It provides some protection against childhood tuberculosis but is less effective in preventing adult disease (11). BCG is commonly given to children in countries in which tuberculosis is prevalent, and is estimated to decrease the risk of contracting the disease by 50% (12).

 

Prevention for High-Risk Travelers

The Centers for Disease Control and Prevention recommend that “travelers who anticipate possible prolonged exposure to people with tuberculosis (for example, those who expect to come in contact routinely with clinic, hospital, prison, or homeless shelter populations) should have a skin or blood test before leaving the United States. If the test reaction is negative, they should have a repeat test 8 to 10 weeks after returning to the United States. Additionally, annual testing may be recommended for those who anticipate repeated or prolonged exposure or an extended stay over a period of years.” (8)

 

The Future

In 2014, the World Health Organization announced that they seek to end the global tuberculosis epidemic by 2035. They defined this goal “with targets to reduce tuberculosis deaths by 95% and to cut new cases by 90%, and to ensure that no family is burdened with catastrophic expenses due to tuberculosis.”  WHO called on the cooperation and collaboration of governments, and suggested a strategy that focuses on highly vulnerable populations (such as migrants) (13). 

In 2020, they announced that the COVID-19 pandemic has stalled progress, as a result of resources being reallocated (2). They noted, for example, that many diagnostic testing machines have been used to test for COVID-19 instead of for tuberculosis. Hopefully, robust testing efforts for the disease will resume soon, as the identification of cases is critical to ending the epidemic.

 

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References

(1) M. Rowe and J. Donaghy, “Mycobacterium bovis: the importance of milk and dairy products as a cause of human tuberculosis in the UK. A review of taxonomy and culture methods, with particular reference to artisanal cheeses”, International Journal of Dairy Technology, vol. 61, no. 4, pp. 317-326, 2008. Available: 10.1111/j.1471-0307.2008.00433.x

(2) “Global Tuberculosis Report”, World Health Organization, 2020. [Online]. Available: https://apps.who.int/iris/bitstream/handle/10665/336069/9789240013131-eng.pdf

(3) “The Clock Is Ticking: World TB Day 2021”, World Health Organization, 2021. [Online]. Available: https://www.who.int/campaigns/world-tb-day/world-tb-day-2021

(4) W. Cruz-Knight and L. Blake-Gumbs, “Tuberculosis”, Primary Care: Clinics in Office Practice, vol. 40, no. 3, pp. 743-756, 2013. Available: 10.1016/j.pop.2013.06.003

(5) “Tuberculosis”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/tuberculosis-12470

(6) U. Seedat and F. Seedat, “Post-primary pulmonary TB haemoptysis – When there is more than meets the eye”, Respiratory Medicine Case Reports, vol. 25, pp. 96-99, 2018. Available: 10.1016/j.rmcr.2018.07.006

(7) “Latent tuberculosis infection (LTBI): FAQs”, World Health Organization, 2021. [Online]. Available: https://www.who.int/tb/areas-of-work/preventive-care/ltbi/faqs/en/

(8) “Tuberculosis: Basic TB Facts: TB Prevention”, Centers for Disease Control and Prevention, Division of Tuberculosis Elimination, 2016. [Online]. Available: https://www.cdc.gov/tb/topic/basics/tbprevention.htm

(9) “Global Health: Newsrooms: Global Health Topics: Tuberculosis”, Centers for Disease Control and Prevention, Global Health, 2020. [Online]. Available: https://www.cdc.gov/globalhealth/newsroom/topics/tb/index.html

(10) “Tuberculosis: Key Facts”, World Health Organization, 2020. [Online]. Available: https://www.who.int/news-room/fact-sheets/detail/tuberculosis

(11) S. Fatima, A. Kumari, G. Das, and V. Dwivedi, “Tuberculosis vaccine: A journey from BCG to present”, Life Sciences, vol. 252, p. 117594, 2020. Available: 10.1016/j.lfs.2020.117594

(12) G. Colditz, “Efficacy of BCG Vaccine in the Prevention of Tuberculosis”, JAMA, vol. 271, no. 9, p. 698, 1994. Available: 10.1001/jama.1994.03510330076038

(13) “WHO End TB Strategy”, World Health Organization, 2021. [Online]. Available: https://www.who.int/tb/post2015_strategy/en/

Springtime Diseases: From Spring Fever to Lyme Disease

by Dr. Jaclynn Moskow

March 20th marks the Spring Equinox when the sun crosses the equator and spring officially begins in the Northern Hemisphere. We generally associate spring with melting snow, blooming flowers, and mating animals; but did you know it is also associated with an increase in the incidence of certain diseases?

There are many factors that cause some infectious diseases to follow seasonal patterns. Changes in temperature and precipitation influence biotic and abiotic environments, disease vectors and hosts, and human behavior, including the amount of time spent outdoors (1). On a molecular level, the numbers of circulating lymphocytes and other immune cells have been observed to vary depending on the season. This may occur as a result of the circadian nature of adrenocortical hormones coupled with fluctuating vitamin D and melatonin levels (2). Additionally, temperature, moisture, and UV light can affect the infectivity of pathogens. The disease pathogens themselves, and their animal and plant reservoirs, insect vectors, and other factors ebb and flow with changes in temperature, rainfall, and many other influences. 

Young pretty girl blowing nose in front of blooming tree. Spring allergy concept

 

Spring Fever

There is actually a historical basis to the term “spring fever.” During the 18th century, individuals sometimes became ill during the springtime, experiencing weakness, joint swelling, loose teeth, and poor wound healing: the clinical manifestations of scurvy (3). As societies became more urbanized, those living in cities were faced with a lack of fruits and vegetables during the winter months, leading some to develop vitamin C deficiency.

Today, scurvy is quite rare. When seen, it is usually among alcoholics or individuals following very extreme diets (4), as opposed to city dwellers lacking access to food sources. The term “spring fever” is now used colloquially to describe a feeling of restlessness and excitement that accompanies the start of spring. “Spring fever” is a disease of the past, but other diseases of springtime remain.

 

Seasonal Allergies/Asthma

Allergies occur when the immune system is triggered by a non-pathogenic substance, resulting in signs and symptoms of inflammation. Many of the same substances that can trigger allergies can also trigger asthma.

Trees, grasses, and weeds produce pollen during the springtime that can instigate allergies and asthma. Additionally, certain molds that are allergenic for some people may increase in number during the spring. Individuals with allergies to pet dander may also see an increase in symptoms, as animals shed their winter coats.

Signs and symptoms of seasonal allergies include congestion, sneezing, coughing, sore throat, post-nasal drip, and headache. Eyes may become red, itchy, watery, and/or swollen. Skin rashes may also be present, as may lymphadenopathy. In extreme cases, anaphylaxis may occur. Asthma is characterized by difficulty breathing, tightness in the chest, wheezing and coughing.

It is estimated that 10–30% of the global population are affected by allergic rhinitis (5). Asthma is less common, affecting about 300 million people worldwide (6.) Those suffering from seasonal allergies will find relief by avoiding known triggers. Utilization of a HEPA filter may be of benefit, as may keeping windows and doors closed. Masks can be worn when gardening and mowing the lawn, and taking a shower immediately after these activities may also provide relief. Frequently brushing and grooming pets and vacuuming dander may also help. 

Oral antihistamines and decongestants can be used, and in extreme cases, corticosteroids may be warranted. Allergy shots are also a key option. Asthmatic attacks can be managed with a number of medications, including corticosteroids, leukotriene modifiers, beta-agonists, theophylline, ipratropium, and various immunomodulators.

Woman with a spring allergy or a cold sneezing with tissue

Rhinoviruses

Rhinoviruses are the most common causes of the common cold. Unlike influenza, which peaks in the winter, rhinovirus cases peak during the fall and spring (7). Rhinoviruses are members of the genus Enterovirus of the family Picornaviridae. Rhinovirus infection has an incubation period of 1-9 days (8).

Rhinovirus infection can resemble seasonal allergies, causing congestion, sneezing, coughing, sore throat, and headache. Unlike with seasonal allergies, muscle aches are also common, and low-grade fever may occur. Rhinoviruses can cause ear infection, and bronchiolitis/bronchitis can develop, especially in children. Rarely, pneumonia may occur. Rhinovirus may also instigate asthma attacks.

Rhinovirus infection is generally self-limiting. Patients may obtain symptomatic relief using nasal decongestants, cough suppressants, and NSAIDs. Many of the same strategies being employed to limit the spread of SARS-CoV-2 can also reduce rhinovirus transmission, including frequent hand washing, avoiding contact with those who are ill and isolating patients.

 

Lyme Disease

Lyme disease is caused by Borrelia spp. and transmitted to humans through the bites of infected Ixodes ticks, often referred to as black-legged ticks/deer ticks. Most cases are acquired from immature ticks (nymphs) which are small (less than 2 mm), and difficult to see. They feed during the spring and summer months (9) – the peak season of Lyme disease (10).

The tick Ixodes ricinus crawling on human skin. This kind of animal is a distributor of Borrelia spp, an agent of Lyme disease
Ixodes ricinus tick is a distributor of Borrelia spp., an agent of Lyme disease

 

Lyme disease has an incubation period ranging from 2-180 days, with most cases manifesting within 7 to 14 days. About 25% of patients recall a recent tick bite. Erythema migrans is present in 75% of cases and is usually neither pruritic nor painful. Multiple skin lesions may occur in 20% to 50% of cases. A nodule in the nipple or ear lobe (borrelial lymphocytoma) may be present. Acrodermatitis chronicum atrophicans can also occur, typically seen on the hands and feet (11). 

Neurological manifestations occur in 10-15% of patients (12). The most common of these include lymphocytic meningitis, cranial neuritis, mononeuropathy multiplex, and painful radiculoneuritis. The range of joint involvement includes tendonitis, myositis, and bursitis, which wax and wane. The cardiac disease may be characterized by arrhythmia, heart block, chest pain, and pericarditis or myopericarditis. Rarely, other organs may become involved. 

Doxycycline, Ceftriaxone, Amoxicillin, and Cefuroxime can be used as a treatment, with dosage, route, and duration varying according to patient age and the nature and severity of the disease.

About 30,000 cases of Lyme Disease are reported to the Centers for Disease Control and Prevention (CDC) each year, but they estimate that as many as 476,000 people will actually contract the disease (13). Most cases occur in Pennsylvania, New York, Connecticut, and other states in the Northeastern United States. The disease is also common in Wisconsin and Minnesota. Lyme disease has been reported in Asia: in China, Korea, Japan, Indonesia, Nepal, and eastern Turkey. In Europe, most Lyme disease cases occur in Scandinavian countries, Germany, Austria, and Slovenia (14).

The CDC recommends that individuals spending time in wooded and grassy areas perform daily “tick checks.” By removing a tick within 24 hours, Lyme disease transmission is greatly decreased. It is important to contact a health professional before attempting to remove a tick. When outdoors, covering skin by wearing long clothing can also reduce transmission. 

Stay safe and Happy Spring!

 

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References

(1) M. Martinez, “The calendar of epidemics: Seasonal cycles of infectious diseases”, PLOS Pathogens, vol. 14, no. 11, p. e1007327, 2018. Available: 10.1371/journal.ppat.1007327

(2) A Fares A, “Factors influencing the seasonal patterns of infectious diseases”, Int J Prev Med, vol. 4, no. 2, pp. 128-32, 2013.

(3) P. Janson, “When Spring Fever Was a Real Disease”, Emergency Medicine News, vol. 38, p. 1, 2016. Available: 10.1097/01.eem.0000484361.70086.35

(4) M. Weinstein, P. Babyn and S. Zlotkin, “An Orange a Day Keeps the Doctor Away: Scurvy in the Year 2000”, PEDIATRICS, vol. 108, no. 3, pp. e55-e55, 2001. Available: 10.1542/peds.108.3.e55

(5) C. Schmidt, “Pollen Overload: Seasonal Allergies in a Changing Climate”, Environmental Health Perspectives, vol. 124, no. 4, 2016. Available: 10.1289/ehp.124-a70

(6) “Asthma”, Who.int, 2021. [Online]. Available: https://www.who.int/news-room/fact-sheets/detail/asthma

(7) A. Monto, “The seasonality of rhinovirus infections and its implications for clinical recognition”, Clinical Therapeutics, vol. 24, no. 12, pp. 1987-1997, 2002. Available: 10.1016/s0149-2918(02)80093-5

(8) Lessler, N. Reich, R. Brookmeyer, T. Perl, K. Nelson and D. Cummings, “Incubation periods of acute respiratory viral infections: a systematic review”, The Lancet Infectious Diseases, vol. 9, no. 5, pp. 291-300, 2009. Available: 10.1016/s1473-3099(09)70069-6

(9) “Lyme disease: Transmission”, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD), 2020. [Online]. Available: https://www.cdc.gov/lyme/transmission/index.html

(10) S. Moore, R. Eisen, A. Monaghan and P. Mead, “Meteorological Influences on the Seasonality of Lyme Disease in the United States”, The American Journal of Tropical Medicine and Hygiene, vol. 90, no. 3, pp. 486-496, 2014. Available: 10.4269/ajtmh.13-0180

(11) “Lyme disease”, GIDEON Informatics, Inc, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/lyme-disease-11360

(12) J. Halperin, “Neurologic Manifestations of Lyme Disease”, Current Infectious Disease Reports, vol. 13, no. 4, pp. 360-366, 2011. Available: 10.1007/s11908-011-0184-x

(13) “Lyme disease: Data and Surveillance”, Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD), 2021. [Online]. Available: https://www.cdc.gov/lyme/datasurveillance/index.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Flyme%2Fstats%2Findex.html

(14) Meyerhoff, J, “What is the global prevalence of Lyme disease?”, Medscape.com, 2019. [Online]. Available: https://www.medscape.com/answers/330178-101008/what-is-the-global-prevalence-of-lyme-disease

Congenital Infections: TORCH

by Dr. Jaclynn Moskow

Pregnant woman cuddling her belly
By obtaining proper prenatal and perinatal care, pregnant women can optimize their chances of preventing, detecting, and treating congenital infections.

 

Congenital infections are caused by pathogens transmitted from a mother to her offspring during pregnancy or delivery. These infections can cause significant fetal and neonatal morbidity and mortality. The mnemonic “TORCH” is often used to refer to common congenital infections:

 

T – Toxoplasma

O – Other (Syphilis, Parvovirus B19, Varicella-Zoster, etc)

R – Rubella

C – CMV

H – Herpes Simplex Virus

 

Congenital Toxoplasmosis

Congenital toxoplasmosis is caused by the parasite Toxoplasma gondii. It can be acquired when a pregnant woman consumes raw or undercooked meat, or contacts contaminated water, soil, or cat feces (generally from outdoor cats that hunt.) The classic triad of congenital toxoplasmosis is 1) chorioretinitis 2) hydrocephalus and 3) cerebral calcifications. 

Symptoms often do not occur until months after birth and may include seizures, cognitive impairment, and cerebellar dysfunction (1). The retinal disease associated with congenital toxoplasmosis is progressive. Other clinical manifestations may include fever, rash, hydrocephalus or microcephaly, sensorineural hearing loss, congenital nephro­sis, hematologic abnormalities, hepatosplenomegaly, various endocrinopathies, and myocarditis. Infection can lead to spontaneous abortion, prematurity, stillbirth, and perinatal death. 

Congenital toxoplasmosis is more severe when acquired in early pregnancy. The incidence is highest in the Eastern Mediterranean and Africa (2). Rates are estimated at 1 per 3000-10000 live births in the United States (3) and 6.7 per 10000 live births in Europe – with 81% of all confirmed cases in the EU/EEA occurring in France (4). Spiramycin can decrease the risk of vertical transmission, but will not treat the fetus if the infection has already occurred. Infants born with this disease may benefit from pyrimethamine, sulfadiazine, and leucovorin. 

To help prevent infection, pregnant women should avoid consuming raw and undercooked meat, wear gloves when gardening, and avoid changing cat litter.

 

Congenital Rubella

Rubella, also known as “German measles,” is caused by the Rubella virus (Togaviridae family). It is most severe when acquired during the first trimester of pregnancy when the maternal infection will lead to fetal demise in 40-90% of cases (5). Congenital rubella can cause cardiac abnormalities, including patent ductus arteriosus and pulmonary artery stenosis. It can also cause ophthalmic abnormalities such as cataracts, glaucoma, retinopathy, and microphthalmia. Sensorineural deafness is common, and microcephaly, cognitive impairment, and meningoencephalitis may occur. Hepatosplenomegaly, hepatitis, hemolytic anemia, and thrombocytopenic purpura may also be observed. 

The incidence of congenital rubella has plummeted in countries that employ widespread vaccination. In recent times, documented cases of rubella in the United States are virtually all imported. Cases and outbreaks continue in Europe but at a very low rate. In 2008, 48% of all cases occurred in Southeast Asia and 38% in Africa (6). There is no effective treatment for congenital rubella.

 

Regional comparison of Congenital Rubella Syndrome prevalence, 1999 – 2019

Congenital infections - Congenital Rubella Syndrome prevalence: comparison between regions worldwide, 1999 - 2019

 

Congenital CMV

Congenital cytomegalovirus (CMV) is the most common congenital viral infection in the developed world. Clinical manifestations include sensorineural hearing loss, visual impairment, cerebral palsy, and cognitive difficulty. It can also cause neonatal cholestasis, pulmonary hypertension, and epilepsy. 10-20% of all hearing impairment in children is caused by congenital CMV (7).

CMV is identified in 5 to 7 per 1000 live births in the USA, Canada, Western Europe, and Australia; and 10-30 per 1000 live births in Latin America, Africa, and most Asian countries (8). Symptomatic infants may benefit from treatment with valganciclovir. It is difficult to prevent the acquisition of CMV, but some have suggested that pregnant women can decrease risk by avoiding contact with the saliva and urine of young children.

 

Congenital HSV

Congenital herpes simplex virus (HSV) most commonly occurs when an infant is exposed to the mother’s genital tract during delivery. Both herpes simplex-1 and herpes simplex-2 can cause congenital HSV. The risk of transmission from mother to infant depends primarily on when the maternal infection was acquired. When a mother is infected close to the time of delivery, the fetal infection rate is estimated at 25-60%. This rate drops to less than 2% when a mother is infected during the first half of pregnancy or earlier (9).

Signs of congenital HSV infection may occur between birth and six weeks of age. Disseminated disease may involve the liver, lung, central nervous system, and skin. “SEM disease” is limited to the skin, eyes, and/or mouth. Congenital HSV may cause a vesicular rash, hypothermia, lethargy, seizures, respiratory distress, hepatosplenomegaly, thrombocytopenia, hepatic dysfunction, cerebrospinal fluid pleocytosis, and sepsis. Congenital HSV is fatal in 50% of cases (10). The incidence of congenital HSV is estimated to be between 1 in 3000-20000 live births. All pregnant women should be tested for HSV, and those who are positive should receive prophylactic acyclovir or a similar drug at the time of delivery. Infected infants should be treated as well.

 

Congenital Syphilis

Congenital syphilis occurs when the bacterium Treponema pallidum is transmitted transplacentally or via the birth canal. The rate of vertical transmission increases as the pregnancy advances and transmission is more likely when the mother is experiencing early disease (11). Congenital syphilis can sometimes be detected by the appearance of nonimmune hydrops fetalis on ultrasound examination.

Congenital syphilis may be divided into two clinical syndromes: early congenital syphilis and late congenital syphilis. The early disease manifests within the first two years of life and is characterized by rash, adenopathy, and hepatosplenomegaly. Mucous patches and condylomata lata may be seen.  The eyes may be affected, and cranial nerve palsy and seizures may occur. Thrombocytopenia with petechiae and purpura are often noted. Other manifestations can include anemia, myocarditis, pancreatitis, nephrotic syndrome, and malabsorption. Osteochondritis is often seen on imaging. 

Late congenital syphilis manifests after two years of age. Dental findings include “Hutchinson’s teeth” and “mulberry molars.” Interstitial keratitis and eighth cranial nerve deafness can occur. Rhagades may be seen. Bone and joint abnormalities may include frontal bossing, saddle nose deformity, protuberant mandible, short maxilla, high palatal arch, sternoclavicular joint thickening (Higouménakis sign), saber shin, and Clutton’s joints. Central nervous system involvement can include cognitive impairment, hydrocephalus, seizures, cranial nerve palsy, paralysis, and optic nerve atrophy.

 

Congenital infections, Syphilis in the United States, 1941 – 2019

 

Graph illustrating the prevalence of congenital infection - Syphilis in the United States, 1941 - 2019

 

The WHO estimates that there were approximately 661,000 total cases of congenital syphilis in 2016, resulting in over 200,000 stillbirths and neonatal deaths (12) – with most cases occurring in South America and Africa. The CDC reports that congenital syphilis is on the rise in the United States, with the number of cases in 2018 being highest since 1998 (13).

All pregnant women should be tested for syphilis at their first prenatal visit. Penicillin is the only known effective antimicrobial agent for the prevention of vertical transmission and treatment of fetal and neonatal infection.

 

Congenital Parvovirus B19

Parvovirus B19 is estimated to infect 1-5% of pregnant women. Most infections are without consequence to the fetus, but in rare cases, serious fetal disease can arise (14). In infected fetuses, ultrasound may show nonimmune hydrops fetalis. 

Congenital parvovirus B19 often causes severe anemia and may also cause thrombocytopenia. Neurological manifestations include hydrocephalus, cerebellar hemorrhage, and polymicrogyria. Cardiac complications can include Ebstein’s anomaly, ventricular septal defect, cardiomyopathy, second‐degree heart block, and myocarditis. Ocular involvement may include corneal opacification, aphakia, and microphthalmia. Gastrointestinal manifestations include meconium peritonitis, fetal liver calcifications, portal tract fibrosis, and hypoplasia of the abdominal muscles. Congenital parvovirus B19 can also cause cleft lip and palate, micrognathia, bifid scrotum, secundum atrial septal defect, and micropenis with perineoscrotal hypospadias.

Intrauterine fetal blood transfusion can be used to treat the severe fetal anemia associated with congenital parvovirus B19 infection. 

 

Congenital Varicella-Zoster

Varicella-zoster congenital infections are caused by the virus that causes chickenpox and shingles. Infection may be characterized by low birth weight, hypoplasia of the extremities, dermal scarring, focal muscular atrophy, encephalitis, cortical atrophy, chorioretinitis, and microcephaly. Neonatal varicella zoster may occur when a mother contracts varicella virus between five days before delivery – to 48 hours after delivery. Neonatal varicella has a fatality rate of up to 30% (15). Congenital Varicella-Zoster virus infection is rare since most women are immune by childbearing age – having either been infected during childhood or vaccinated. Infants born with congenital varicella zoster may improve with acyclovir. 

 

Additional Congenital Infections

Additional viral agents of fetal and neonatal morbidity and mortality include HIV, Hepatitis B and C, measles, enteroviruses, adenovirus, lymphocytic choriomeningitis virus, West Nile virus, Zika virus, and Chikungunya virus. Additional bacterial causes include Group B Streptococcus, Chlamydia trachomatis, Neisseria gonorrhoeae, , Escherichia coli, Mycobacterium tuberculosis, and Coxiella burnetii. A parasite, Plasmodium falciparum (the causative agent of malaria) is also associated with congenital infection. 

By obtaining proper prenatal and perinatal care, pregnant women can optimize their chances of preventing, detecting, and treating congenital infections. 

 

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References

(1) Hampton MM. Congenital Toxoplasmosis: A Review. Neonatal Netw. 2015;34(5):274-8. doi: 10.1891/0730-0832.34.5.274.

(2) Rostami A, Riahi SM, Contopoulos-Ioannidis DG, Gamble HR, Fakhri Y, Shiadeh MN, Foroutan M, Behniafar H, Taghipour A, Maldonado YA, Mokdad AH, Gasser RB. Acute Toxoplasma infection in pregnant women worldwide: A systematic review and meta-analysis. PLoS Negl Trop Dis. 2019 Oct 14;13(10):e0007807. doi: 10.1371/journal.pntd.0007807.

(3) McAuley JB. Congenital Toxoplasmosis. J Pediatric Infect Dis Soc. 2014 Sep;3 Suppl 1(Suppl 1):S30-5. doi: 10.1093/jpids/piu077.

(4) “Congenital toxoplasmosis – Annual Epidemiological Report for 2016”, European Centre for Disease Prevention and Control, 2021. [Online]. Available: https://www.ecdc.europa.eu/en/publications-data/congenital-toxoplasmosis-annual-epidemiological-report-2016. 

(5) Best JM. Rubella. Semin Fetal Neonatal Med. 2007 Jun;12(3):182-92. doi: 10.1016/j.siny.2007.01.017. 

(6) Bouthry E, Picone O, Hamdi G, Grangeot-Keros L, Ayoubi JM, Vauloup-Fellous C. Rubella and pregnancy: diagnosis, management and outcomes. Prenat Diagn. 2014 Dec;34(13):1246-53. doi: 10.1002/pd.4467. 

(7) Goderis J, De Leenheer E, Smets K, Van Hoecke H, Keymeulen A, Dhooge I. Hearing loss and congenital CMV infection: a systematic review. Pediatrics. 2014 Nov;134(5):972-82. doi: 10.1542/peds.2014-1173. 

(8) Fowler KB, Boppana SB. Congenital cytomegalovirus infection. Semin Perinatol. 2018 Apr;42(3):149-154. doi: 10.1053/j.semperi.2018.02.002.

(9) Fernandes ND, Arya K, Ward R. Congenital Herpes Simplex. 2021 Jan 11. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 29939674.

(10) Westhoff GL, Little SE, Caughey AB. Herpes simplex virus and pregnancy: a review of the management of antenatal and peripartum herpes infections. Obstet Gynecol Surv. 2011 Oct;66(10):629-38. doi: 10.1097/OGX.0b013e31823983ec.

(11) Cooper JM, Sánchez PJ. Congenital syphilis. Semin Perinatol. 2018 Apr;42(3):176-184. doi: 10.1053/j.semperi.2018.02.005.

(12) “WHO publishes new estimates on congenital syphilis”, World Health Organization, 2021. [Online]. Available: https://www.who.int/reproductivehealth/congenital-syphilis-estimates/en/.

(13) “STD Facts – Congenital Syphilis”, Cdc.gov, 2021. [Online]. Available: https://www.cdc.gov/std/syphilis/stdfact-congenital-syphilis.htm.

(14) Ornoy A, Ergaz Z. Parvovirus B19 infection during pregnancy and risks to the fetus. Birth Defects Res. 2017 Mar 15;109(5):311-323. doi: 10.1002/bdra.23588. 

(15) “GIDEON”, App.gideononline.com, 2021. [Online]. Available: https://app.gideononline.com/explore/diseases/varicella-12550.

Pathogen of the month: Chikungunya virus

by Dr. Jaclynn Moskow

 

Chikungunya virus, 3D illustration. Emerging mosquito-borne RNA virus from Togaviridae family that can cause outbreaks of a debilitating arthritis-like disease
3D illustration of the Chikungunya virus

 

Chikungunya refers to an infection caused by the Chikungunya virus, an alphavirus of the Togaviridae family. Like its close relative, the Semliki Forest virus, the Chikungunya virus is transmitted from human to human via mosquito bites. 

Chikungunya is characterized by fever, joint and muscle pain, and rash.  The disease was discovered in Tanzania in 1952, and since that time has been identified in over 60 countries around the world. The word “Chikungunya” means “that which bends up” in the Makonde language, spoken by a group indigenous to Tanzania and Mozambique. It is thought that this term was coined to describe the posture of patients affected with severe disease.

 

Transmission

Mosquito species that carry Chikungunya include Aedes aegypti in the tropics, Aedes albopictus in the tropics and colder areas, and approximately one dozen Aedes species in Africa, including Aedes furcifer and Aedes taylori. Transmission occurs after a mosquito bites someone infected with Chikungunya and then subsequently bites someone else. Mosquitos pick up the Chikungunya virus from human blood, the virus then replicates inside the mosquito and can be transmitted via their salvia. Once a mosquito acquires the virus, it will likely carry it for the rest of its life. There is evidence that some animals, including non-human primates, rodents, and birds, may act as reservoirs for the Chikungunya virus.

Aedes aegypti Mosquito. Close up a Mosquito Mosquito on leaf,Mosquito Vector-borne diseases,Chikungunya.Dengue fever.Rift Valley fever.Yellow fever.Zika virus.
Aedes aegypti mosquito, the vector of Chikungunya

 

Signs and Symptoms

Signs and Symptoms of Chikungunya develop after a 2-12 day incubation period. Cases vary in severity, and asymptomatic infection may occur. The rate of asymptomatic cases is estimated to be between 4% and 28%.

Cases often begin with an abrupt onset of fever. Polyarthralgia occurs in 70% of cases, usually involving small joints. Swelling of joints may also occur, typically without fluid accumulation. In greater than 50% of cases, a maculopapular rash on the palms, soles, limbs, torso, and/or face is present. This rash may progress to desquamation. Fever generally resolves within one week, but joint pain may persist for months. Sometimes, a “saddle-back fever curve” is seen, with fever resolving and then returning. Moderate to severe lymphopenia is often noted. Thrombocytopenia, leukopenia, elevated liver enzymes, anemia, and elevated creatinine may also be observed.

Facial and neck erythema and conjunctival suffusion may be noted. Headache, photophobia, retro-orbital pain, pharyngitis, nausea, and vomiting can occur. Sometimes, pneumonia and dry cough are seen. Pruritus is common. Patients may complain of exhaustion and insomnia. Symptoms of Chikungunya can persist from one week to several months. Residual chronic joint pain may continue in some cases. Chronic disease is more common in older patients and patients with prior rheumatological disease.

Chikungunya can also cause neurological and ophthalmologic complications. Eye involvement may include retinitis, retinal detachment, optic neuritis, uveitis, dendritic lesions, and Fuchs heterocyclic iridocyclitis. Neurological manifestations can include altered mental function, encephalitis, seizures, myelopathy, Guillain-Barré syndrome, bulbar palsy, acute flaccid paralysis, focal neurological deficit, and sudden sensorineural hearing loss.

Additional rare complications of Chikungunya include hemorrhagic syndrome, cardiovascular shock, arrhythmias, myopericarditis, renal failure, rhabdomyolysis, and thrombocytopenic purpura.

Children with Chikungunya are more likely to experience neurological and dermatological symptoms, and less likely to have arthralgia. Transplacental transmission of the virus can occur and may result in neonatal encephalopathy, neonatal respiratory distress, sepsis, necrotizing enterocolitis, and cardiologic complications. Infants who become infected during the perinatal period may experience fever, rash, peripheral edema, lymphopenia, and thrombocytopenia. Congenital and perinatal infections are associated with poor neurodevelopmental outcomes. Transmission of Chikungunya via breastfeeding has not been noted.

Fatalities from Chikungunya are rare, occurring in about 1 per 1,000 cases. Fatalities are more common in newborns and individuals with multiple medical comorbidities. The use of NSAIDs prior to hospitalization is associated with an increase in disease severity. Infection with Chikungunya is likely to protect against future disease. 

 

Diagnosis and Treatment

A diagnosis of Chikungunya should be considered in individuals living in – or having traveled to – areas with known outbreaks presenting with acute onset of fever and joint pain. Dengue fever and Zika virus infection should be considered in a differential diagnosis of Chikungunya, as they are also carried by Aedes species mosquitoes and may present with similar signs and symptoms.

PCR, serology, and viral culture can be used for laboratory confirmation of Chikungunya. Chikungunya is classified as a biosafety level-3 pathogen, and samples should be handled accordingly. Blood-borne transmission from patients to healthcare workers and laboratory personnel has been documented.

Patients with Chikungunya are treated with supportive care, including hydration and pain management. It is important to prevent mosquito bites during the first week of illness, in order to prevent additional transmission.

 

Chikungunya outbreaks

Between 1952 and 2013, Chikungunya virus outbreaks were identified in Africa, Asia, Europe, and the Indian and Pacific Oceans. In 2013, cases were first identified in the Americas and nations of the Caribbean, and today the majority of cases occur in these locations – where populations have no preexisting immunity.

Over the past decade, the countries that reported most cases of Chikungunya have included Haiti, Dominican Republic, Guadeloupe, Martinique, El Salvador, Honduras, Nicaragua, Columbia, Bolivia, Brazil, Ethiopia, Chad, India, Laos, and French Polynesia. If you have a GIDEON account, click to explore Chikungunya Outbreak Map.

Between 2004 and 2006, an outbreak of Chikungunya that began in Kenya resulted in 500,000 cases in countries of the Indian Ocean, including one-third of the population of La Reunion Island. This outbreak spread to India, where almost 1.5 million people were infected. Ongoing outbreaks have been occurring in Brazil since 2014, with over 300,000 cases occurring in 2016. It is thought that a mutation occurred around 2005 that enabled the virus to survive in Aedes albopictus; and that having this additional species as a vector has fueled recent outbreaks.

Local transmission was reported for the first time in Europe in 2007, with 197 cases occurring in north-eastern Italy. The source of this outbreak was traced to a single individual who had returned from India with the infection. A second outbreak occurred in Europe in 2014, centered mainly in France and the UK and resulting in about 1500 cases.

Chikungunya cases in United States, 2006 - 2020, GIDEON graph

 

In 2014, local transmission of the Chikungunya virus was identified in the territories of the United States for the first time, with 4,659 cases occurring between American Samoa, Puerto Rico, the U.S. Virgin Islands, and Florida. Since that time, the rate of local transmission in the United States has decreased each year, with 179 cases occurring in 2016, 8 cases in 2018, and no cases in 2020.

 

Prevention

There is currently no vaccine to prevent Chikungunya. The CDC recommends the use of the Environmental Protection Agency (EPA)-registered insect repellents when traveling to areas with outbreaks. Wearing long sleeves and pants can also reduce transmission, as can sleeping in places with air conditioning and window and door screens. The CDC also recommends using 0.5% permethrin to treat clothing and gear to repel mosquitos.

During outbreaks, measures should be taken to control mosquito populations by reducing both natural and artificial water-filled habitats where they may breed. Any items that may hold water, such as pools, buckets, planters, and trash containers, should be regularly emptied and cleaned.

 

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This blog was written using data from the GIDEON database, CDC, and WHO.

What infectious diseases are due to be eradicated next?

Timeline of infectious disease eradication

 

Although Medical Science aims to eradicate Infectious Diseases in order to protect life and reduce the healthcare burden, it has only been able to achieve that goal against two diseases to date. While this remains a difficult task, there is a genuine possibility that additional diseases will be eliminated in the near future! Let’s explore the diseases that have been consigned to history…and those that are set to join them soon.

Smallpox: declared eradicated in 1980

Following a concentrated global effort spanning more than 20 years, Smallpox became the first infectious disease to be eradicated by mankind.  Smallpox was characterized by high fever, vomiting, and an extensive skin eruption characterized by vesicles, pustules, and permanent scarring. Thirty percent of cases were fatal, and recurring outbreaks affected virtually all countries,  leading to the deaths of as many as 300 million humans during the 20th century. 

The disease has already been eliminated in North America and Europe when, in 1959, the World Health Organization declared the eradication initiative to permanently eradicate Smallpox. A vaccine with enhanced efficacy became widely available in 1967, and a formal Eradication Programme was put into effect. The last cases were reported in Africa in 1977, and WHO officially declared that Smallpox had been eradicated in 1980.

Rinderpest: declared eradicated in 2011

31 years later, a second disease joined the “eradicated” list. Rinderpest was a viral disease that affected cattle and other hoofed animals. The condition was responsible for the deaths of countless livestock prior to the 20th century, causing fever, loss of appetite, and severe diarrhea. While not known to infect humans, this disease had a significant impact on food security and the livelihoods of countless individuals who worked in related industries. 

A vaccine was developed in 1918 and was improved upon throughout the 20th century, eventually leading to the eradication of Rinderpest in most regions. The FAO (Food and Agriculture Organization) initiated the Global Rinderpest Eradication Programme in 1994, which led to the last reported cases in 2001, Kenya. The official declaration of the eradication of Rinderpest was released in June 2011.

What are we eradicating right now?

Eradicating now: diseases that are in the process of being eradicated

The world is very close to eradicating wild Polio, with only 33 cases reported globally in 2018 and 176 in 2019, following an eradication initiative that began in 1988. Initially, the goal was to eliminate Poliomyelitis by 2019.  Although small pockets of infection continue to fester into 2021, workers in the field feel that mankind is very close to the eradication of this disease. 

Guinea Worm Disease (Dracunculiasis) is also “on the radar.”  This is a crippling parasitic disease, which is extremely painful and can prevent its victims from working and living normal lives for several months – a disaster for agricultural areas in Africa, where the disease is reported. Eradication of this disease was originally targeted to occur in 1981, and efforts were given further impetus by the WHA (World Health Assembly) in 2001.  Their goal is very much at hand… only 54 cases were reported in 2019!

Another lesser-known disease on the path to eradication is Yaws, which the WHO has been working to eradicate since the 1950s.  The bacterium which causes Yaws is closely related to the agent of syphilis and can be easily treated with a small dose of antibiotics. 80,472 suspected cases of Yaws were reported in 2018,  of which 888 were confirmed.

Finally, a more familiar disease – Rabies – is also targeted for eradication. The World Health Organization is working to prevent all human deaths from Rabies by 2030 while vaccinating all wild and domestic carnivores (foxes, dogs, etc) as well. 17,400 cases of human rabies were reported in 2015, and 29 million individuals were treated following the bites of animals that may have carried the disease. In 2019, Mexico was the first country to be validated by WHO for having eliminated human deaths from dog-mediated rabies; and hopefully, the rest of the world can soon follow suit and rid us of yet another disease.

What’s next?

Beyond the diseases mentioned there are several well-known diseases – such as Tuberculosis, HIV infection, and Malaria –  that could possibly be eradicated in the coming years. New drugs and vaccines are continually being developed, and the advent of the COVID-19 vaccine has demonstrated that a concentrated effort can make all the difference.

 

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21st century outbreaks

21st century outbreaks infographic, displaying top 10 diseases with the most outbreak cases between 2001-2020

 

Which diseases have generated the highest number of cases from outbreaks during the first two decades of the 21st century?  In this blog, we can use GIDEON’s data to find out.

‘Disease outbreak’ is a scary term for many, but every year we suffer dozens, if not hundreds, of localized and international disease outbreaks across the world. While these outbreaks are always significant to those affected, they rarely generate headlines,  and can sometimes go unnoticed outside of the Healthcare Industry.

An “outbreak” is often defined as an increase in case numbers for a particular disease in a defined place and time. Outbreaks can evolve into pandemics (such as with COVID-19) or consist of an isolated cluster of cases, especially for rare and less-communicable diseases, and can persist for years and even decades.

GIDEON collects information on all cases of Infectious Disease worldwide, and much of this effort involves gathering data on outbreaks. The following list has been created using these data, assessing all outbreaks in excess of 500 cases reported from January 2001 to November 2020 – from the GIDEON database of 361 diseases and 233 countries and territories.

  1. Hand, foot & mouth disease (Enterovirus infection) – 2.9+ million outbreak cases

Prominent in Asia, especially over the last 10 years, the most significant outbreaks occurred in 2016 and 2017 – accounting for over 2 million out of total cases. The disease typically affects children, causing a distinctive rash, fever, and nausea (not to be confused with foot-and-mouth disease, which generally only affects livestock).

  1. Viral Conjunctivitis – 4.3+ million outbreak cases

Many outbreaks of this disease were recorded across Asia and South America, the most significant of which was in South Korea in 2002. The latter outbreak resulted in more than 1 million cases. Brazil has also suffered repeated outbreaks, with 10,000 to 100,000 cases reported throughout this period. Often linked with upper respiratory diseases, viral conjunctivitis is also referred to as a ‘pink eye’ due to its principal symptom.

  1. Measles – 5.4+ million outbreak cases

Surprisingly, measles has been one of the most common causes of outbreaks into the 21st century, involving much of the world.  The most notable of these outbreaks occurred in 2019, with nearly 1.5 million cases reported across 50 countries. The disease is best known for its distinctive combination of fever, cough, and a florid rash.

  1. Viral Meningitis – 5.4+ million outbreak cases

While the bacterial variant of the disease is typically associated with large outbreaks in sub-Saharan Africa (a region known as the ‘meningitis belt’), viral meningitis outbreaks are far more common.  Unusually large outbreaks have been reported in China, often affecting neighboring countries as well. Over 4.5 million cases were reported in the region between 2008 and 2012.  Viral meningitis is associated with a stiff neck, headaches, and high fever. Fortunately, rates of fatal viral meningitis have been steadily decreasing for a number of years.

  1. Chikungunya – 9.7+ million outbreak cases

Sometimes mistaken for Dengue or Zika, Chikungunya was most active in the Americas region in recent years.  Even the United States has reported local transmission, which South American countries have experienced hundreds of thousands of Chikungunya cases. Joint pain, high fever, and a rash are the characteristic symptoms, with headaches, chronic pain, and insomnia appearing in later stages of the disease.

  1. Viral Gastroenteritis – 10.2+ million outbreak cases

This entry is a bit of an anomaly here since the vast majority of cases were associated with a single outbreak. In 2006, viral gastroenteritis in Japan was caused by Norovirus, with no less than 10 million cases, – impacting the entire country. Symptoms include diarrhea and/or vomiting, accompanied by abdominal cramps and fever.

  1. Cholera – 12.8+ million outbreak cases

Cholera is an ancient disease that continues to produce regular and significant outbreaks, with case numbers in the 100,000s almost every year. A recent large outbreak that began in 2016 in Yemen, continues to this date – already totaling more than 2.4 million cases. The disease causes severe diarrhea and vomiting, resulting in extreme loss of fluids that can turn a patient’s skin to a bluish-gray color – as they succumb to dehydration. 

  1. Dengue – 26.0+ million outbreak cases

The number of Dengue outbreaks has been increasing in recent years, with cases reaching almost 5 million in 2019 alone. Brazil has experienced major difficulties with this disease, as have neighboring countries, and much of Asia and Africa. Dengue is characterized by high fever, vomiting, headaches, musculoskeletal pain, and a characteristic rash. 

  1. Malaria – 27.7+ million outbreak cases

This mosquito-borne disease typically causes fever, headache, fatigue, and vomiting, but can be complicated by seizures, coma, multi-organ failure, and death in severe cases. Malaria outbreaks have been somewhat less frequent than other diseases on our list over the  21st century; however, the severity and impact of malaria outbreaks are relatively high.  Two major outbreaks of over 8 million cases each have occurred during the past four years. This is not to downplay the overall burden of disease, which the World Health Organization estimated to be as high as 229 million cases in 2019 alone.

Graph of malaria cases worldwide 1973 - today, GIDEON
Malaria cases worldwide 1973 – today, GIDEON

 

 

  1. COVID-19 – 64.5+ million outbreak cases (at the time of writing)

A disease which did not even exist until eleven months ago – is at the top of our list.  The growing number of cases and deaths have made “COVID-19” the most commonly used word used by mankind.  The disease can have a wide range of symptoms but commonly causes coughing, fever, loss of smell and taste, and breathing difficulty. Elderly individuals and those with pre-existing conditions are particularly at risk of developing complications. Even with a vaccine available in the next few months, we must all remain cautious and follow safety measures at all times. 

 

Stay healthy, stay safe!

 

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Pneumonia – “a disease of the ancients”

Doctor examining a lung radiography - pneumonia
Doctor examining a lung radiography

 

The COVID-19 pandemic has been a painful reminder of how important lung health is. But there are many other threats to this very vital organ. Numerous lung diseases have plagued the human race throughout history, and doctors have been working tirelessly to find effective means of beating them – a battle that continues to the present day. 

While many diseases cause symptoms in the lung, several of them attack this organ directly. “Pneumonia” is not a single disease, but rather a generic term for inflammatory conditions affecting the lungs. Pneumonias affect hundreds of millions of people each year, and are the leading causes of mortality among both children and elderly individuals, with an estimated 4 million deaths every year [1]. 

An old enemy

Pneumonia has existed for thousands of years, with Hippocrates himself describing the symptoms during the fifth to fourth centuries BCE [2]. Knowledge of the disease likely dates back even further, as Hippocrates himself considered it to be ‘named by the ancients’. The name appears to be derived from the Greek word pneúmōn, meaning ‘lung’.

Maimonides’ (12th century) stated ‘The basic symptoms that occur in pneumonia and that are never lacking are as follows: acute fever, sticking pleuritic pain in the side, short rapid breaths, serrated pulse, and cough.’ This is mirrored by many modern textbooks even today.

It was not until the late 1880s that the link between bacteria and pneumonia was established.  This concept was prompted by Edwin Klebs in 1875, who first observed the bacteria in patients dying from the disease (the bacterial genus Klebsiella is named after him) [3]. Viral pneumonia was not discovered until 1938, by Hobart Reimann [4].

 

Four types of pneumonia

Is pneumonia contagious? Yes, and it has a wide etiological spectrum – including a large variety of bacteria, viruses, fungi [5] which cause alveoli (air sacs) in one or both lungs to become inflamed and fill with fluid or pus, resulting in restricted breathing ability.

The choice of treatment is largely determined by the nature of the infecting organism – and will include one or more antibiotics, antiviral drugs, or antifungal agents.

A number of clinical “clues” may help the doctor decide which pathogen is involved in a given case of pneumonia.   For instance, Mycoplasma pneumoniae infection is most frequently observed in patients below the age of 30 and is often accompanied by a bullous otitis media and a ‘hacking’ cough. Pneumocystis pneumonia, on the other hand, is characterized by dyspnea and hypoxia – and is usually encountered in severely immunosuppressed patients.

GIDEON chronicles the epidemiology of pneumoniae caused by bacteria such as Streptococcus pneumoniae, Klebsiella pneumoniae, Chlamydia, Mycoplasma pneumoniae, and fungi, such as Cryptococcus neoformans and Pneumocystis jirovecii.

 

History of treatment

An extensive array of therapeutic options have evolved for the treatment of pneumonia. Hippocrates pioneered thoracic drainage, leaving tubes in place for up to two weeks [6];  while in medieval times we might have encountered the occasional bloodletting. As crude as those methods may seem, the treatments of the early 20th century were far from elegant, though somewhat more comfortable.

Electronic inhalers such as the one shown below have now been consigned to the history books and museums. While the design of inhalers improved considerably during the last 100 years, their function has changed little. 

 

A woman using an electric inhaling apparatus which produces a medicated fog used in the treatment of colds and influenza, circa 1929.
A woman using an electric inhaling apparatus which produces a medicated fog, circa 1929. Rare Historical Photos.

 

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References:

[1] “Pneumonia”, Who.int, 2020. [Online]. Available: https://www.who.int/news-room/fact-sheets/detail/pneumonia. 

[2] R. Feigin, Textbook Of Pediatric Infectious Diseases, 5th ed. Philadelphia: Saunders, 2004, p. 299.

[3] I. Gerard and K. Root, “Pneumonia”, Library.leeds.ac.uk, 2017. [Online]. Available: Pneumonia | Special Collections | Library | University of Leeds.

[4] F. Wagner and J. Hodges, Thomas Jefferson University: Tradition and Heritage. Philadelphia, Pa.: Jefferson Digital Commons, 1989, p. 253.

[5] “Pneumonia”, John Hopkins Medicine, 2020. [Online]. Available: https://www.hopkinsmedicine.org/health/conditions-and-diseases/pneumonia. 

[6] S. Walcott-Sapp and M. Sukumar, “A History of Thoracic Drainage: From Ancient Greeks to Wound Sucking Drummers to Digital Monitoring”, Ctsnet.org, 2015. [Online]. Available: https://www.ctsnet.org/article/history-thoracic-drainage-ancient-greeks-wound-sucking-drummers-digital-monitoring. 

Hepatitis C

Hepatitis C is a recently discovered disease. Harvey J. Alter identified the variant form of Hepatitis during the 70s, which then became known as a ‘non-A, non-B Hepatitis (NANBH)’. In the 1980s, Michael Houghton and his team isolated the genome of the new virus, and it was named ‘Hepatitis C’. Finally, in 1997 Charles M. Rice proved that the virus is a disease agent, capable of acting alone to cause Hepatitis.

This year’s Nobel Prize in Medicine has been jointly awarded to Harvey J. Alter, Michael Houghton, and Charles M. Rice for the discovery of the virus. Their contributions (illustrated below) have led to improved understanding, prevention, and treatment of the disease.

 

Nobel Prize in Physiology or Medicine 2020 to HJ Alter M Houghton and CM Rice for discovery of Hepatitis C virus

 

5 types of Hepatitis

There are five known types of viral Hepatitis – A, B, C, D, and E –  of which types A and B and E are currently preventable by vaccines.  Over 71 million cases of chronic Hepatitis C infection were estimated in 2015, though that number has been steadily falling over the past decade. The majority of deaths are caused by liver cancer or cirrhosis brought on by the infection, with an estimated 399,000 fatal cases in 2016.

To learn more about the differences between Hepatitis A, B, and C, see our earlier blog here.

Diagnosis and treatment

Hepatitis C can often be asymptomatic, or associated with mild symptoms, and may smolder for up to six months before becoming active. Acute infections are associated with fatigue, nausea, fever, abdominal pain, and loss of appetite; while chronic infections are more often associated with progressive dysfunction of the liver.

Although many laboratories are seeking an effective vaccine for this disease, currently available antiviral drugs have been shown to cure more than 95% of infections. 

The World Health Organization is approaching the end of its Global Health Sector Strategy on Viral Hepatitis, 2016-2021 which has the vision of reducing new infections by 90% – and deaths by 65%- by 2030.

The universal presence of this disease demands a robust response from all health authorities across the globe,  and recognition given by the Nobel committee will raise the profile of the disease and encourage new avenues for research into Hepatitis C treatment and prevention.

 

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Learn more about Hepatitis C

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