by Dr. Jaclynn Moskow
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:
- Contact with animals and animal products (zoonoses)
- Exposure to vectors
- Care of patients
- Environmental sources, exposure to soils
- Occupational skin infections
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
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
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
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
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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(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.