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Birds Positive For WNV
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Two cases of positive tests for West Nile Virus in San Joaquin County make the use of mosquitofish and other mosquito deterrents all the more important.

In recognition of National Mosquito Control Awareness Week, June 23 through June 29, the San Joaquin County Mosquito and Vector Control District (District) is distributing mosquitofish free to residents of all cities and surrounding rural areas within San Joaquin County. In Escalon, the distribution is today, Wednesday, June 26, at the Escalon Community Center, parking lot, between 12:30 p.m. and 2:30 p.m.

“Ideal places to use mosquitofish to prevent mosquito development are ornamental ponds, animal water troughs, and neglected swimming pools” said Aaron Devencenzi, Public Information Officer with the District.

A maximum of 15 fish will be provided to each resident as long as supplies last. Residents will be asked to provide their name, address and the location where fish will be placed.

Mosquitofish were first introduced in California in 1922 and have since spread throughout the state. They are a live-bearing minnow closely related to the common guppy. Mosquitofish are temperature dependent for reproduction, but typically breed from mid-spring to fall in the San Joaquin Valley. They reproduce at intervals of about six weeks, with on average about 50 young in a single brood.

Mosquitofish are the primary biological control agent for the San Joaquin County Mosquito & Vector Control District.

Meanwhile, district officials recently confirmed that two dead Western Scrub-Jays found in the Manteca area zip code 95336, have tested positive for West Nile Virus (WNV). These are the first birds to test WNV positive in San Joaquin County for 2013. The dead birds follow two samples of mosquitoes testing positive for WNV, reported by the District on May 24, 2013 in southern San Joaquin County.

“As temperatures rise, West Nile virus amplifies in the mosquito and bird populations. This amplification cycle increases the risk of mosquito-borne disease transmission. This most recent find of WNV in an urban area serves as a reminder that residents should make a habit of taking precautions against mosquito bites,” said Devencenzi.

Further WNV positive finds in San Joaquin County will be available on the District website at

Residents and visitors of San Joaquin County can reduce their risk of WNV and other mosquito-transmitted diseases by taking these precautions: Eliminate all sources of standing water on your property that can support mosquito breeding; apply insect repellent containing the active ingredient DEET or Picaridin when outdoors, according to label instructions; avoid spending time outside when mosquitoes are most active, at dawn and dusk, and especially for the first two hours after sunset; when outdoors, wear long pants, long-sleeved shirts and other protective clothing.

Also, exclude mosquitoes from your home with tight fitting screens on doors and windows; contact your veterinarian for information on vaccinating equine against WNV; and report significant mosquito infestations to San Joaquin County Mosquito and Vector Control District at (209) 982-4675, 1-800-300-4675, or