Vermont Confirms Human Case of West Nile Virus Illness
State also warns Vermonters that ticks are active now, so know how to avoid bites
BURLINGTON, VT – The Vermont Department of Health has confirmed a case of human illness due to West Nile virus. This is the first such case since 2017. A Chittenden County resident was diagnosed earlier this month with neuroinvasive disease – a more serious form of the illness which affects the nervous system. The individual was hospitalized but has since been released.
West Nile virus is spread through the bite of an infected mosquito. The virus has been found in all counties of Vermont. Most people who are infected do not become ill from the virus. Fewer than one percent of people develop more severe illness, but around 20 percent develop flu-like symptoms, such as high fever, muscle aches, headache and fatigue.
Since 2003, there have been 14 confirmed human cases of West Nile virus in Vermont. Two residents were diagnosed with West Nile neuroinvasive disease in 2017. There have been no human cases of the more deadly Eastern equine encephalitis (EEE) since 2012.
Each year, the Health Department and Agency of Agriculture, Food and Markets conduct mosquito surveillance throughout the state, testing for West Nile virus and EEE. During the 2021 testing season which ended a few weeks ago, 1,668 mosquito pools were tested for West Nile virus and EEE – all were negative.
State Public Health Veterinarian Natalie Kwit, DVM said the risk of mosquito-borne illness for the year is almost over, as mosquito season ends with the first hard frost. But until then, Dr. Kwit advises Vermonters to stay informed on how to avoid bites and infection.
Horse owners are urged to consult with their veterinarians and follow recommendations to ensure appropriate vaccination for this and other vector-borne diseases. While horses cannot spread the virus to humans or other horses, it can cause neurologic disease and death in unvaccinated animals. In 2018 an unvaccinated horse died from the virus.
Ticks are Active
While the risk of arboviruses is slowing, health officials are urging Vermonters to be alert for ticks, which are looking to feed before winter sets in.
“Tickborne illnesses in Vermont are most common from early spring through late fall,” said Dr. Kwit. “People think that once the days become shorter and cooler that the risk is over. In fact, this is a time of year when ticks are particularly active.”
Dr. Kwit said the Health Department is concerned about the increasing rates of tickborne diseases, such as anaplasmosis – which is transmitted by the black-legged tick, the same tick that spreads Lyme disease and is the most common tick found in Vermont.
“It’s important that people are vigilant in avoiding tick bites,” said Dr. Kwit. “As you plan to go outdoors, for yard work or just to get out and enjoy autumn in Vermont, take these easy steps to avoid tickborne diseases – limit your exposure to ticks and tick habitats, wear a repellent containing up to 30% DEET, check your body and your pets for ticks, and promptly remove attached ticks.”
For information about mosquito surveillance and arboviruses, visit healthvermont.gov/mosquitos.
Learn more about ticks and tick-borne disease, visit healthvermont.gov/BeTickSmart
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