Jamestown Canyon Virus (JCV) was first identified in 1961 in mosquitoes collected from Jamestown Canyon, Colorado. It belongs to the California serogroup of bunyaviruses and is closely related to La Crosse encephalitis virus. Since its discovery, JCV has been found in various mosquito species across the United States and Canada, and it continues to be a concern due to its potential to cause severe neuroinvasive diseases and death.
In 2024, there was one confirmed human case of JCV in New Hampshire. Since 2011, there have been 13 reported cases in Massachusetts, 19 in New Hampshire, 4 in Maine, 4 in Rhode Island, 1 in Connecticut, and 5 in New York. According to the CDC, there have been a total of 308 JCV cases across the country, with 10 deaths from 2011 to 2023.
The JCV transmission cycle involves mosquitoes, deer, and humans. The cycle begins when mosquitoes, particularly those that feed on deer, become infected with the virus. Deer serve as the primary reservoirs, carrying the virus in their bloodstream without showing symptoms. After feeding on an infected deer, the virus replicates within the mosquito. When the infected mosquito bites another host, such as a human or another deer, it transmits the virus through its saliva. Humans are considered dead-end hosts because they do not develop high enough levels of the virus in their bloodstream to infect other mosquitoes, thus not contributing to the spread of the virus.
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