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West Nile birds in Alpine add up to eight with Marshall Road case
By Christy Scott
The Alpine Sun
ALPINE — A recent case of West Nile Virus found in a bird that tested positive for the disease, brings the number of known cases among birds to eight.
The bird, a Western Scrub Jay, was found by a homeowner on Marshall Road and reported to San Diego Vector Control.
“I called vector control in the morning before coming to work,” the resident said, “and they were there by 10:30 in the morning to pick up the bird.”
Upon preliminary testing at the county level, the jay tested negative for West Nile, however, after being sent to the state for more thorough tests it came back positive.
“The state tests are much more thorough,” said Chris Conlan, senior vector ecologist with the San Diego County Department of Environmental Health. “They go into more detail. We’ve seen at least four cases in Alpine that have tested positive after coming up negative in the initial test.”
According to vector control, the bird could have been infected by mosquitos breeding right in the area in horse troughs, still portions of Alpine Creek and run-off to sedimentation basins built by Reynolds Communities for its housing development.
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| Lisa Hilko, of the San Diego County Vector Control program holds up the dead jay that later tested positive for positive for West Nile Virus. |
The latest positive West Nile case brings the Alpine total to eight. There have also been three cases found in Campo and Jamul, two cases in Pine Valley and one case in Potrero and Descanso. All of the birds that tested positive were American crows and Western Scrub Jays.
County Vector Control officials announced recently that the total number of positive birds in San Diego is 58 this season. This more than triples the number of dead birds that tested positive at this time last year.
According to the county, Alpine has been one of the hardest hit areas in the county.
Anyplace where there is standing water, from stopped-up culverts to swimming pool covers, are choice breeding grounds for
mosquitoes, which may carry the West Nile virus.
According to county officials, vector control has been conducting aerial spraying on standing water spots around the county — but Alpine and the Back Country are not among them.
“The aerial applications are designed for fairly large mosquito breeding areas that are overgrown with vegetation and difficult for our field staff to treat,” said vector control program cheif Jack Miller. “In East County, our field technicians can treat all of the mosquito breeding sources by land. We have identified several mosquito breeding sites in the Alpine area and East County and our staff visit the locations and treat any mosquito breeding they find.”
“We've got a lot more water out there, and that's a big concern,” Conlan said.
According to Conlan, the Vector Control Program has been conducting monthly aerial mosquito larvicide applications to difficult-to-access areas that are known for mosquito breeding. The larvicides act specifically on mosquito larvae and will not harm other wildlife. They are applied by helicopter every four weeks to the vegetation in certain bodies of water.
Financing of aerial spraying cost to control disease outbreaks is provided by state or local emergency funds in many places. In San San Diego county, however, unincorporated property owners cover the costs of treatment for the rest of the county via an add-on to their property tax bills.
According to the county department of environmental health, the county has aggressively attacked mosquito populations in the past few years, depleting a reserve account set up to pay for the vector-control program.
“Because we have found so many positive birds in Alpine we have focused our efforts in the area and are using a helicopter to look for ponds that we are not aware of and green swimming pools,” Miller said. “We also are focusing additional outreach efforts in areas that have had a high number of positive dead birds.”
“With West Nile virus, we accelerated our spend-down of the account by two or three years,” Miller said.
In May 2005, property owners countywide were asked to impose an increased benefit fee on themselves to be collected with property taxes. The tax was approved by 61 percent of the 216,000 ballots that were returned, making the fee $8.55 a year per house and $2 a year for apartments. The fee increases are expected to generate $9.6 million this year, more than four times the $2.3 million the county now collects.
Money from the increase was to be used for existing services, in addition to a program expansion that would include hiring staff to treat 1,000 mosquito breeding sites monthly. The spraying, however, has not extended past Santee into East County and no Back Country areas have been treated. The most recent application took place on Sept. 28.
As the weather cools down and the fall months proceed, mosquitos will keep to a slower breeding pace, going from egg to adult in three weeks. Should the days warm to the 80s, with nights in the 50s, development time shortens to 10 days.
“They're already breeding. It's just a matter of how quickly they're going to go,” Conlan said.
“We are now past the peak transmission period,” said Dr. Vicki Kramer, chief of the vector-borne disease section of the state Department of Health Services. “However, the public needs to keep in mind, based on our experience last year and on those of other areas, that people can get infected in September and October.”
In the meantime, the county is reminding people to eliminate stagnant water, no matter how small the amount, and to protect themselves by wearing insect repellent. Particular hot-spots for mosquito breeding include horse troughs, and childrens’ swimming pools. Any spot where water is still and sits for any amount of time can be a potential breeding site. The county is compiling a list of sites where people can pick up free mosquito fish, which will eat mosquito larvae in backyard ponds and fountains.
Horses are of particular concern in Alpine and the Back Country. Statewide, horse owners are encouraged to immunize their horses. Horses are tested for the virus during vet check-ups, and any West Nile present is reported to vector control by the veterinarian.
Two vaccines for horses are available and equally effective, according to vector control officials. Although administering vaccinations against the West Nile virus will not completely protect them from the disease, the shots can significantly reduce the animals’ chances of being killed by it. There have been no documented cases of WNV this year in local horses.
“The average horse owner in San Diego County is vaccinating for the disease. That's why we enjoyed a rather unremarkable 2004,” Conlan said.
There is no vaccine for humans. Most people infected with West Nile won't become sick. About 20 percent will experience flulike symptoms such as fever, headache, fatigue and body aches.
The impact of WNV on wildlife species is yet to be known, however, a recent study by the University of California found that the North American strain of WNV has been particularly aggressive. In recent years, nearly 200 species of birds, reptiles and mammals fell ill from West Nile this year, including rabbits, squirrels and reindeer, pelicans and bats.
West Nile is not fatal in all animals, and over time some species are expected to adapt. But even partial drop-offs in key populations could have serious consequences. According to the Agriculture Department Wildlife Research Center, rodent populations could blossom in areas where raptors are dying, and pest birds such as house sparrows may be increasing where crows are absent.
Statewide last year, there were 829 reported human cases, 27 fatal. Nationwide, 2,470 human cases, 88 of them fatal, were reported to the Center for Disease Control and Prevention. There has been one reported case of WNV in humans in the county so far this year.
To report dead birds, one may call (888) 551-4636.
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Courtesy, San
Diego County Vector Control
Total number of positive WNV cases in birds in San Diego County. |
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