Despite the emergence in recent years of infectious illnesses like chikungunya, West Nile and Zika that traditionally have been considered more “exotic,” Lyme disease is the most common vector-borne disease in the U.S.
,
Nearly 35,000 confirmed and probable cases of Lyme disease were reported in the country in 2019, according to the Centers for Disease Control and Prevention, marking a 4% increase over 2018. Yet the actual number of annual cases is likely higher: With the key caveat that patients can be presumptively treated for a condition, around 476,000 Americans each year were diagnosed and treated for Lyme disease between 2010 and 2018, authors with the CDC estimated in a 2021 analysis of insurance claims data.
,
Typically concentrated most heavily in the Northeast, mid-Atlantic and Upper Midwest, a total of 15 states and the District of Columbia as of 2019 were categorized as areas with “high incidence” of Lyme disease, defined by the CDC as having an average incidence of at least 10 confirmed cases per 100,000 persons for three reporting years. Meanwhile, the number of counties with incidence rates of 10 or more confirmed cases per 100,000 increased from 324 in 2009 to 432 in 2019, according to the CDC.
,
Bacteria that causes Lyme disease is spread through the bite of infected blacklegged or western blacklegged ticks, and the CDC says the disease left untreated can cause a number of symptoms, including fever, rash, arthritis and facial paralysis. Early diagnosis and treatment with antibiotics are recommended to prevent later-stage illness. Guidance also recommends removing a tick as soon as possible to reduce the risk of infection.
,
These are the 10 states with the highest incidence rates of Lyme disease per 100,000 persons in 2019, the most recent year for which data has been posted by the CDC.