|
|
West Nile Fact Sheet Shasta Mosquito and Vector Control District
Current Status as of September 6, 2002 There has been one occurrence of human exposure to West Nile Virus (WNV) in California so far. This is unusual since the disease has not been detected in the environment in dead birds, mosquitoes or other animals in California. Horse cases in Wyoming are the furthest west that this virus has been found in nature in the U.S. so far. The virus has been detected in the U.S. in all but the six most westerly states excluding California. Statistics on disease and fatalities in the U.S. are changing on a daily basis, so it is best to check the CDC news web site for the most current possible information at: http://www.cdc.gov/od/oc/media/wncount.htm Information specific to California is available at http://westnile.ca.gov/
Biology of WNV West Nile Virus is a mosquito-borne disease that is closely related to Saint Louis Encephalitis (SLE). Although SLE occurs naturally in California, WNV was unknown in the United States prior to an outbreak in the vicinity of New York City in 1999. WNV is typically found in Africa, Asia and Europe, primarily in areas bordering the Mediterranean basin. This virus is normally found in wild birds and is spread only through the blood-feeding activities of mosquitoes on infected birds. Mosquito-borne encephalitis viruses rarely cause serious symptoms in birds though the effects on humans and horses can be quite severe. WNV differs, as it has been associated with major bird die-offs since it has gotten to the U.S. In particular, crows and their relatives such as jays, ravens and magpies are frequently killed by WNV infection in the U.S.
WNV in Humans and Horses It is believed that many cases of WNV infection in humans show no disease symptoms. Disease symptoms may range from flu-like fever and headache, to swelling of the brain (encephalitis), which can lead to paralysis, coma and death. In humans, WNV is fatal in approximately 10% of cases showing encephalitis symptoms. WNV is available for horses, though veterinarians are not universally recommending the vaccine at this time. Horse owners should consult their veterinarian for a recommendation regarding immunization.
Shasta Mosquito and Vector Control District (SMVCD) Activities SMVCD has stepped up its manpower to increase the number of mosquitoes sampled for virus activity in the District. In addition, District personnel may be sent out by the California Department of Health Services to retrieve dead birds reported within or near the District to be sampled for WNV infection. California residents observing freshly dead crows, ravens, jays or magpies should call the California State West Nile Virus Dead Bird Hotline 1-877-WNV-BIRD or 1-877-968-2473 to determine if their local District will retrieve the bird for testing. SMVCD uses blood sampling of sentinel chicken flocks to monitor for the presence of encephalitis virus in the bird population within the District. The District also traps live mosquitoes, which are sent to state labs and tested for the presence of encephalitis viruses. SMVCD has been performing mosquito control to protect the public health since 1919 when this area has some of the highest occurrences of malaria in the nation. The District has a multi-faceted, integrated, and environmentally compatible program of mosquito control, which includes surveillance, physical control of mosquito sources, public education and chemical control of adult and larval mosquitoes.
For More Information:
(530) 365-3768
|