Published Date: 2003-08-21 23:50:00
Subject: PRO/AH/EDR> West Nile virus, mosquitoes - USA (CA)
Archive Number: 20030821.2105

WEST NILE VIRUS, MOSQUITOES - USA (CALIFORNIA)
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Date: Thu 21 Aug 2003
From: Michael Ziccardi <mhziccardi@ucdavis.edu>
Source: University of California, Davis, News, Wed 20 Aug 2003 [edited]
<http://www-news.ucdavis.edu/search/news_detail.lasso?id=6590>

California: West Nile Virus-positive Mosquitoes Found
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Relying on tests conducted by the University of California, Davis, the
California Department of Health Services today announced the first evidence
of West Nile virus in the state in 2003. The UC Davis tests showed that
mosquitoes collected in Imperial County near the Salton Sea were carrying
the virus. The mosquitoes were collected by UC Davis staff researchers in
the Wister Unit of the Imperial Wildlife Area, on the southeast rim of the
Salton Sea. They were tested by laboratory staff members at the UC Davis
Center for Vectorborne Diseases.
The state health department also said that preliminary tests at state
laboratories showed that flocks of sentinel chickens from the same region
are likely infected with West Nile Virus. The blood tests indicate that the
chickens, which are kept in flocks outdoors, were bitten by mosquitoes
infected with West Nile or a closely related virus, the health department
said. The Department of Health Services coordinates statewide efforts to
prevent the spread of the virus and to watch for it in mosquitoes, wild
birds, sentinel chickens, horses, and humans.
UC Davis, with the largest West Nile research and testing programs in the
state, is fundamental to those public-health efforts. "During the 2003
season we have tested more than 5000 groups of 1 to 50 mosquitoes each, as
well as tissue samples from birds and other animals, for the presence of
West Nile virus," said John Edman, director of the Center for Vectorborne
Diseases and a UC Davis professor of medical entomology. "All were negative
until Tuesday, when we discovered West Nile virus in this group of 27
_Culex tarsalis_ mosquitoes we collected near the Salton Sea."
UC Davis researchers recently showed that, among some 200 mosquito species
in the United States, _Culex tarsalis_ is the species that transmits West
Nile virus most effectively. UC Davis professor of entomology Thomas Scott
and his students discovered that _C. tarsalis_ can spread the virus most
efficiently to hosts such as birds, horses, and people. A significant
proportion can pass the virus through its eggs to its offspring.
The UC Davis Center for Vectorborne Diseases performs the tests for the
state of California to detect West Nile virus in samples from mosquitoes,
wild birds, horses, and other animals. Samples from sentinel chickens and
humans are tested for viral antibodies in the state laboratories in Richmond.
More information on today's announcement by the California Department of
Health Services, along with public safety tips, is posted at
<http://www.dhs.ca.gov>.
--
Michael Ziccardi DVM MPVM PhD
Director, Oiled Wildlife Care Network
Sr. Wildlife Veterinarian/Epidemiologist
Wildlife Health Center
University of California
Davis, CA 95616
<mhziccardi@ucdavis.edu>
[This is the first confirmation of the spread of West Nile virus as far
west as the state of California. 2 previous human cases of West Nile virus
infection in California are believed to have been a consequence of exposure
to the virus outside of the state. - Mod.CP]

See Also

West Nile virus update 2003 - USA (01) 20030103.0016
West Nile virus update 2003 - USA (19) 20030807.1946
West Nile virus update 2003 - USA (20) 20030815.2034
West Nile virus update 2003 - USA (21) to be archived
West Nile virus, human - USA (CA ex CO) 20030816.2051
2002
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West Nile virus update 2002 - USA (12) 20020719.4797
West Nile virus update 2002 - USA (34) 20021219.6096
West Nile virus - USA 2001: final report 20020613.4491
West Nile virus, human - USA (CA) (02) 20020909.5265
West Nile virus, human - USA (CA) (03): confirmed 20020912.5286
West Nile virus, human - USA (CA) (04) 20020913.5293
West Nile virus, human -USA (CA) (05): final confi... 20020913.5295
West Nile virus, human - USA (CA): suspected 20020906.5247
2001
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West Nile virus surveillance - USA 2000 final report 20010423.0792
West Nile virus surveillance - USA 20010129.0207
West Nile virus surveillance 2001 - USA (34) 20011130.2914
West Nile virus, horses - USA 2000: final report 20010831.2079
2000
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West Nile virus surveillance - USA 20000720.1198
West Nile virus surveillance - USA (54) 20001223.2267
West Nile virus, Congressional report - USA 20000626.1056
1999
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West Nile virus - USA: Summary to date 19991022.1890
West Nile virus - USA: USGS summary 19991029.1958
West Nile virus - USA: USGS summary (02) 19991103.1972
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