West Nile Virus: 35 States Active, First Reported 2009 Horse Death in California

When West Nile virus (WNV) made its march from East Coast to West Coast starting in late 1999, California was one of the last states to be struck by the disease. In the past couple of years, California has one of the the highest rates of West Nile virus problems in the country, and it now has recorded its first horse death for 2009 due to the disease, which is spread by mosquitoes.

Nearly every county in California has had birds or mosquitoes discoverd this year that test positive for West Nile virus (WNV), according to the Centers for Disease Control. The first horse death due to West Nile virus was reported near Tracy, Calif., on Aug. 6. There has also been one human case reported in San Joaquin County, where the horse resided, according to an article on recordnet.com

In 2008 there were 64 "veterinary" cases, which can include any animals reported by veterinarians. The vast majority of those were horses (according to the CDC it's 99.9% of the time horses that are reported). July and August of 2008 saw the start of the peak of cases, with the number of cases spiking in August and September.

Local California officials are encouraging horse owners to vaccinate their animals against West Nile virus and are undertaking spraying to reduce mosquito populations.

Other states with West Nile Virus activity (positive samples, cases, or testing due to concern about WNV) this year, according to the Centers for Disease Control, include: Arizona, Colorado, Connecticut, Georgia, Hawaii, Idaho, Illinois,Indiana, Kentucky, Louisiana, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New York, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West virginia, Wisconsin, and Wyoming.

Horse owners are encouraged to talk to their veterinarians about vaccination protocols to protect horses from West Nile virus.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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