Arboviruses
Last 28 Days Positive Samples in California
As part of California's vector control efforts, samples from a variety of sources are regularly tested for the presence of West Nile virus, St. Louis encephalitis and Western equine encephalomyelitis. The map below is provided to illustrate the ongoing efforts to detect and control the these diseases. Use the layer checkboxes below the map to enable or disable the various layers.
St. Louis Encephalitis Virus
St. Louis encephalitis virus (SLE), a member of the flavivirus family, was the most important mosquito-borne arbovirus in North America up until 1999, when West Nile virus (WNV) was introduced into the United States. Wild birds are the maintenance and amplifying hosts of SLE, which is transmitted among birds and to humans by primarily Culex mosquitoes. Human infection with SLE can result in mild to severe illness, with case-fatality rates ranging from 3%-30%.
