Mosquito season underway and the public is asked to fight the
spread of West Nile
It’s warm, it’s wet and the region has become a robust breeding
ground for disease-carrying mosquitoes.
Mosquito season underway and the public is asked to fight the spread of West Nile
It’s warm, it’s wet and the region has become a robust breeding ground for disease-carrying mosquitoes.
It’s warm, it’s wet and the region has become a robust breeding ground for disease-carrying mosquitoes.
As the days grow longer and warmer, when people spend more time out of doors, those little flying pests we call mosquitoes start to come out in full force. With the abundance of rain this year, and the sudden warm weather and higher humidity, experts warn that this mosquito season could be a bad one.
But its not the bothersome itchy red bites that have local vector control officials concerned – it’s the spread of West Nile Virus that has them putting out the word on mosquito prevention.
“Since we’ve gone from winter to summer, the humidity has been high and mosquitoes do like high humidity,” said Kriss Costa, a community resource specialist with the Santa Clara County vector control district. “Mosquito season is January through December. We have more exposure [now] because we are outside.”
Despite warnings that 2005 would have high numbers of West Nile infections, the rates in Santa Clara and San Benito turned out to be mild. Santa Clara had 153 mammal infections, 144 of which were dead birds. The counties had no human fatalities from West Nile virus.
San Benito had only two reports of infected horses and one dead bird with the virus. The difference in the numbers between the two counties could be due more to a lack of reporting than to an actual discrepancy in the prevalence of the disease, Costa said.
“San Benito has a more rural area,” she said. “They have more wildlife that can pick up dead birds and eat them before anyone sees them.”
Other factors could be that San Benito’s abatement program is new so that people may have been reporting less dead birds in the county.
In San Benito, which does not have a vector control district, the job of preventing West Nile Virus is divvied up among several departments. The agricultural commissioner’s office handles mosquito abatement under a program launched in 2005. The public health department is providing information on virus.
Both counties said they have a good handle on most places within the county where mosquitoes are likely to breed.
“We did win the battle last year and we hope we can win it again,” Costa said. “We were right on top of it. Our technicians were out hitting all the sources.”
But the do need input from residents to combat other areas mosquitoes might be breeding.
“We have a handle on all the normal sources,” Costa said. “It’s the backyard sources – the curbs that are holding water all summer or someone’s area that got flooded during all this rain.”
The first year West Nile enters an area, the infection tends to be localized to a small region, such as it was in San Jose last year.
“When we did find the infected mosquitoes, we were able to knock them down,” Costa said. “We had a small area that we had targeted as the hot zone and low and behold that’s what happened.”
During the second and third year, the virus spreads out.
“We had dead birds from Santa Clara and Saratoga,” she said. “The dead birds are tending to be farther out so we know we don’t have the luxury of a small area.”
The dead birds to report include crows, jays, magpies and raptors such as owls and hawks.
San Benito County, which is still collecting baseline information on mosquitoes in the region, has other challenges as West Nile Virus spreads.
“We had more water this year later on [in the season],” said Matt Fore, a registered environmental health specialist with San Benito County. “Just anecdotally people are saying they are finding collected water in areas we haven’t seen for a while.”
Both Fore and Costa emphasized the ways that local residents can help by reporting dead birds and by removing possible breeding areas from their backyards and neighborhoods. Backyard water sources can range from flowerpot saucers, buckets or swimming pools that are not properly emptied.
“The more people can get out and remove possible sources, the less number of sources,” Costa said. “The less number of sources, the less possibility of mosquitoes. The less possibility of being bitten by an infected mosquito.”
The virus carried by the mosquitoes is common in Africa, Western Asia and the Middle East, but didn’t make its way to the United States until 1999. Experts considered the disease a seasonal epidemic that flares up during the summer and into fall, according to the California Department of Health Services.
The disease has spread its way across the United States and has been watched closely by state agencies in California during the last three years.
In the most severe cases, which strikes about 1 percent of the population, West Nile Virus can be fatal or debilitating. Sever symptoms include high fever, headaches, vision loss, numbness and paralysis, among others.
In the majority of cases, people will have only mild or no symptoms at all, health officials say. About 80 percent of those infected exhibit no symptoms, while 20 percent will have body aches, skin rashes or swollen lymph glands.
“The reason West Nile is such a big issue is because it can be carried by more than one species of mosquito,” Costa said. “The main carrier is one that generally lives in residential areas.”
Experts are still learning about how the disease is spread and its symptoms.
“One thing they have learned on the health side of it is that it isn’t as benign as people thought,” Costa said. “Some effects are lasting as long as 18 months to two years. The majority of people will never notice they have it, but those who do have problems are suffering longer.”
Fight the bite
Statewide mosquito districts offer the four “Ds” as a solution:
