C. Adult Mosquito. Encephalitis is generally involved in a mosquito-bird cycle with both hosts serving as reservoirs, but humans or horses may be accidental end points with occasionally serious consequences. Generally, encephalitis is clinically inapparent. Clinical signs include fever, and a severe headache, often followed by rapid complete recovery. Older people, however, may have a high fever, nausea, vomiting, chills, severe headache, convulsions, speech problems, confusion, and drowsiness.
Recovery is often dramatically rapid without complications.
However, in a few patients, weakness, dulled mentality, and paralysis may be side effects. In rare cases, death may occur. Positive diagnosis can only be made serologically or by recovery of the virus. Heartworm disease of dogs, caused by Dirofilaria immitis , is also transmitted by mosquitoes. Adult worms live in the heart and pulmonary arteries.