| St. Louis Encephalitis
is an important mosquito-borne disease in the
USA. This virus like other arboviruses, is maintained in nature through
biological transmission of virus between vertebrate hosts and
blood-sucking arthropods. During an SLE epidemic, large numbers of people
become infected, however, only a very small percentage of the SLE
infections are systematic and the majority are never diagnosed. Symptoms
range from mild headaches, coma or in rare cases death. Other symptoms
include fever, nausea, stiff neck/back, light sensitivity, confusion,
drowsiness, irritability, and motor skill impairment. Wild bird populations
are central to the transmission cycle. An infected bird can produce an
appreciable amount of virus in one or two days, but the virus disappears
two to three days later, so a bird remains “infective” for only a few
days. Birds do not show any symptoms of disease and become immune after
exposure. Culex nigripalpus
mosquitoes in
Florida
are the major vector. There is no cure for the disease nor are there
vaccines available. Medical treatment is available only for the symptoms.
Control of the disease relies upon preventing transmission to humans or
breaking the virus cycle in nature, such as reducing vector mosquito
population. |