Orange County, Calif., Vector Control District (OCVCD) biologists have found antibodies to West Nile virus (WNV) in two adult female house finches. The birds were trapped as part of the District’s wild bird trapping program which involves trapping and releasing dozens of wild birds each week after drawing a small blood sample. The two birds were bled on March 2, 2004, and tested at the District lab in Garden Grove. One of the birds was also trapped and sampled on Feb. 18, 2004 and showed no antibodies at that time.

“This evidence is an indication that active virus transmission has already begun in the county. Our wild bird bleeding program is an early warning system that alerts us to virus activity prior to any human cases” stated James P. Webb PhD, OCVCD Technical Director.

West Nile virus is carried by birds and is passed on to mosquitoes when they feed on an infected bird. The disease can then be transmitted by the bite of an infected mosquito to humans or other animals. The disease usually goes unnoticed though a small percentage of the population will experience flu-like symptoms, and an even smaller percentage can become seriously ill; about 240 people died as a result of WNV in 2003.

Horses are particularly hard hit by WNV, mortality rates approach 40%, but there are two vaccines available, and horse owners are encouraged to have their animals vaccinated