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Encephalitis

Technically, encephalitis means swelling of the brain. Many things including a bite from a mosquito infected with the encephalitis virus can cause this serious disease. Clinical symptoms of mosquito-transmitted encephalitis vary from mild cases showing little or no symptoms to more severe infections, which show fever, headache, convulsions and coma. Most people infected with the virus show little or no disease symptoms. The two most common types of mosquito-borne encephalitis in California are St. Louis Equine Encephalitis and Western Equine Encephalitis.

St. Louis Encephalitis

  • Cause: Disease caused by a mosquito transmitted virus.
  • Incubation: period usually 5-10 days.
  • Symptoms: Fever, severe headache, nausea, and stiff neck. Severe cases may include vomiting, disorientation and paralysis.
  • Diagnosis: By physician using acute phase serum or cerebral spinal fluid.
  • Treatment: There is no specific treatment for infection. Supportive care is important (contacting your physician, fluids, electrolytes, managing fever, etc.).

Mosquito vector:

Known Occurrences in Napa County

No confirmed human cases reported in Napa County.

Western Equine Encephalitis

  • Cause: Disease caused by a mosquito transmitted virus.
  • Incubation:period usually 5-10 days.
  • Symptoms: May have flu-like symptoms including fever, headache and lethargy. Severe cases may include vomiting, anorexia, disorientation and paralysis.
  • Diagnosis: By physician using acute phase serum or cerebral spinal fluid.
  • Treatment: There is no specific treatment for infection. Supportive care is important (contacting your physician, fluids, electrolytes, managing fever, etc.).

Mosquito vector:

Known Occurrences in Napa County

No confirmed human cases reported in Napa County. The virus for Western Equine Encephalitis was last detected in the Calistoga area in 1996.