Jamestown Canyon Virus

Jamestown virus was first isolated from mosquitoes near Jamestown, Colorado in 1961. It is closely related to La Crosse virus. Jamestown virus is transmitted to people by infected mosquitos. Mosquitos become infected when they feed on infected deer. The virus is found throughout much of the United States, but Minnesota and Wisconsin have reported more than half of the cases. Most infections occur between April and September. 

The time from mosquito bite to development of symptoms ranges from a few days to 2 weeks. Initial symptoms can include fever, fatigue, myalgia, and headache. People who are immunocompromised are more likely to develop severe disease. Jamestown Canyon Virus can cause meningoencephalitis with symptoms of stiff neck, confusion, loss of coordination, and seizures. Approximately half of infected people are hospitalized but deaths are rare. Approximately 17 neuroinvasive cases are reported each year. 

Lumbar puncture in patients with neuroinvasive cases may show a lymphocytic cerebrospinal fluid (CSF) pleocytosis with normal glucose and elevated protein.

Diagnosis is usually made by testing for Jamestown Canyon virus-specific IgM antibody in blood or cerebrospinal fluid. Due to significant antibody cross-reactivity with other viruses in the California serogroup, any positive IgM should be followed by a confirmatory plaque reduction neutralization test (PRNT). Rarely, Jamestown Canyon virus infection may be diagnosed by reverse transcription-polymerase chain reaction (RT-PCR) tests on serum or CSF samples from immunocompromised patients.

References

Patriquin G, Drebot M, Cole Teri, et al. High seroprevalence of Jamestown Canyon virus among deer and humans, Nova Scotia, Canada. Emerg Infect Dis 2018;24:118‒121.

Pastula DM, Hoang Johnson DK, White JL, Dupuis AP, Fischer M, Staples JE. Jamestown Canyon virus disease in the United States — 2000–2013. Am J Trop Med Hyg 2015;93:384–389.

Coleman KJ, et al. An Overview of Jamestown Canyon Virus Disease. Neurohospitalist. 2021 Jul;11(3):277-278. doi: 10.1177/19418744211005948.