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.
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.
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.
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 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).
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!
Did you like this article? Share it on social media!
(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