Clinical Signs and Symptoms of Jamestown Canyon Virus Disease

Clinical presentation

Most cases of Jamestown Canyon virus disease occur from April through September. Unlike La Crosse virus infections which occur mostly in children, there is no clear age predilection for Jamestown Canyon virus disease, although most cases have been reported among adults.

Jamestown Canyon virus disease should be considered in any person with an acute febrile or neurologic illness who has had recent exposure to mosquitoes during spring through fall in the United States. Other causes of encephalitis and aseptic meningitis should also be considered, as appropriate (e.g., herpes simplex viruses, enteroviruses, West Nile virus, St. Louis encephalitis virus, La Crosse virus, Powassan virus).

Signs and symptoms

Many Jamestown Canyon virus infections are asymptomatic, but the specific symptomatic-to-asymptomatic ratio is not known. Among patients who are symptomatic, initial symptoms are non-specific, including fever, fatigue, or headache. Some patients also report respiratory symptoms, such as cough, rhinitis, or pharyngitis. The incubation period for Jamestown Canyon virus disease is unknown.

Some patients with Jamestown Canyon virus disease might develop meningitis or encephalitis with possible meningismus, seizures, altered mental status, and cerebrospinal fluid (CSF) pleocytosis.

Clinical assessment

With Jamestown Canyon virus neuroinvasive disease, CSF findings typically include lymphocyte-predominant pleocytosis, elevated protein levels, and normal glucose levels.

Outcomes

About half of known Jamestown Canyon virus disease cases have been hospitalized. However, deaths are rare and have been primarily reported in immunocompromised patients.