Clinical Features and Diagnosis of Cache Valley Virus Disease

Epidemiology

Cache Valley virus is a Bunyamwera serogroup virus in the genus Orthobunyavirus, family Peribunyaviridae. The virus is widely distributed in mosquito populations throughout North America and parts of Central America.

The transmission cycle is not well understood, but the virus has been isolated from a broad range of mosquito species (including Anopheles, Culiseta, Coquillettidia, and Aedes species) and the main vertebrate hosts are likely ungulates (e.g., deer, cattle, horses, and sheep).

Only rare human disease cases have been identified, including cases reported from Illinois, Michigan, Missouri, New York, North Carolina, and Wisconsin. All cases have occurred from late spring through early fall.

Clinical considerations

Cache Valley virus disease should be considered in patients with an acute febrile or neurologic illness who have had recent exposure to mosquitoes during spring through fall. 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).

Cache Valley virus disease is a nationally notifiable condition. All cases should be reported to local public health authorities in a timely manner. Reporting can assist local, state, and national authorities to recognize outbreaks and to implement control measures to reduce future infections.

Signs and symptoms

Initial symptoms of Cache Valley virus disease are non-specific, including fever, headache, nausea, vomiting, fatigue, and sometimes rash. Severe disease presentations range from aseptic meningitis to fatal encephalitis.

The case fatality rate cannot be determined based on the small number of reported cases. Some patients who recovered from acute Cache Valley virus disease later died from complications of illness.

Diagnostic testing

Diagnostic methods include serological testing of serum or cerebrospinal fluid (CSF) and viral culture performed on serum, CSF, or tissue specimens. In fatal cases, testing of autopsy specimens can be performed.

To submit specimens for testing, please contact your state or local health department. They can assist you with determining if samples should be sent to the CDC Arbovirus Diagnostic Laboratory for further testing. Specimens should be submitted to CDC through state health departments. All results will be sent from CDC to the appropriate state health department.