Fresno County health officials said Tuesday that a dead crow is the first recorded bird death from West Nile virus there this year. No bird deaths associated with West Nile have been reported in Merced.
The crow’s death in Fresno is a signal that the virus is present in the area, and health officials reminded people to protect themselves from mosquito bites.
Mosquitoes become infected from biting birds and then pass the virus to humans and horses.
Most people infected with West Nile virus have no signs of illness, or mild, flu-type symptoms, but the disease can cause neurological problems and death.
Last year saw 372 cases of West Nile virus in California and 14 deaths. There were no deaths in the Valley, but Fresno County reported seven illnesses. Tulare had five illnesses, Madera had three and Kings County had one.
Merced County had no positive West Nile virus cases last year. However, Merced, Gustine, Hilmar and Winton issued mosquito warnings, which are given when mosquitoes carrying the virus are detected, according to Allan Inman, manager at the Merced County Mosquito Abatement District.
Inman said that 17 bird deaths have been reported to the district’s hotlines this year, but only one has met the criteria for West Nile testing, and the results were negative.
“We have taken notice of the bird deaths (from West Nile Virus) in Fresno, Santa Clara and San Joaquin counties,” Inman said. “These are close to Merced, so we’re working on making sure we’re prepared.”
The Mosquito Abatement District is scheduled to place mosquito traps at the Merced County fairgrounds in June. The traps target female mosquitoes looking for a place to lay eggs.
Mosquitoes carrying the virus tend to bite at dawn and dusk.
Fresno health officials asked people to report any day-biting mosquitoes, which could be Aedes aegypti. The mosquito was first identified in the county last summer and has been detected this spring, the officials said.
The mosquito is not native to California, but last year, it was found in Fresno, Clovis, Madera and Fowler. This year it has been trapped in Clovis, and a female Aedes aegypti mosquito was caught in a Madera trap.
No illnesses have been associated with the mosquito in central San Joaquin Valley counties. There is no indication of disease in the mosquitoes trapped this spring, but they can carry diseases such as yellow fever.
The Aedes aegypti mosquito is brown with white markings. An aggressive day-biter, it is commonly found in hot, humid tropical areas such as the southeastern United States, Mexico and Central and South America.
The Merced County Mosquito Abatement District recommends that people stay indoors at dusk and dawn, wear clothes that protect the skin from bites and use mosquito repellant containing DEET.
For more information, the abatement district can be reached at (209) 722-1527.
Sun-Star staff writer Ana B. Ibarra contributed to this article.