Symptoms, Diagnosis, & Treatment


There have been relatively few cases of Cache Valley virus disease identified. The incubation period (time from mosquito bite to symptoms onset) is not currently known but is likely a few days to two weeks.

  • Initial symptoms can include fever, headache, nausea, vomiting, fatigue, and sometimes rash.
  • Cache Valley virus can cause severe disease, including infection of the brain (encephalitis) or the membranes around the brain and spinal cord (meningitis).
    • Symptoms of severe disease (meningitis or encephalitis) include stiff neck, confusion, loss of coordination, difficulty speaking, or seizures.
    • Some patients with severe disease have died.


If you think you or a family member might have Cache Valley virus disease, talk with your health care provider. Your healthcare provider can order tests to look for Cache Valley virus infection or other infections that cause similar symptoms.

More information on diagnostic testing is available on the For Healthcare Providers page.


  • There are no medications to prevent or treat Cache Valley virus infection. Antibiotics do not treat viruses.
  • Rest, fluids, and over-the-counter pain medications may relieve some symptoms.
  • People with severe disease often need to be hospitalized to receive support for breathing, staying hydrated, or reducing swelling in the brain.

To learn more about treatment, visit our Healthcare Providers page.