Prepare For A Season Of West Nile Worries

By Carie L. Call

Staff Writer

Ginny Day subjects herself to repeated mosquito bites on a daily basis.

A biologist with the Charlotte County Health Department's mosquito control division, Day stands in areas where she knows mosquitoes are hatching -- and allows them to bite her. She then counts the bites. The "test" tells her how many mosquitoes are living in a specific location.

"I've been bitten by too many to count," Day says with a laugh.

Day doesn't fear it, but the mosquitoes biting her could carry West Nile virus, an illness not found in North America prior to 1999, but one that has since swept the nation, causing hundreds of human deaths.

A mosquito is a vector of West Nile -- which means it first bites an infected bird, then carries the virus to each new victim it bites. Mosquitoes also can infect horses, bears, squirrels, cats and dogs. West Nile has even been found in pelicans, flamingos and alligators.

Day is predicting a moderate mosquito season in Charlotte County this year. She said because there has been more rain this winter than in the past two years, there will be more mosquitoes this summer.

"But I don't think it will be as bad here as it will be in North Central Florida," Day said. "It probably won't be an exceptionally high year."

Lyman Roberts, an entomologist and parasitologist for Sarasota County's Mosquito Management Services, does not have such a rosy outlook.

"Studies show that if you have a wet early spring, then a relatively dry period and then more rain -- which is what we had -- we're in store for a difficult season," Roberts said. "I think we're in store for one more bad year and this could be the year."

If mosquitoes do overrun Southwest Florida this year, the only precautions people can take against the bites and West Nile virus is to use common sense and bug repellent. There is no vaccine against West Nile for humans.

Pregnancy Precautions

The virus can cause flu-like symptoms in people, including headache, fever and fatigue. It is not contagious, but has been transmitted from a pregnant woman to her child and during organ transplant operations. This year, pregnant women are being advised to avoid mosquitoes.

The virus can ultimately cause a swelling of the brain -- and death. But most people who are bitten by infected mosquitoes don't get sick. The virus mostly affects children and the elderly, as well as people with compromised immune systems.

Wendy Luke, activities assistant at Life Care Center, a retirement facility in Punta Gorda, is arming herself with common sense to protect her charges. Luke said because of the summer heat and mosquitoes, she doesn't plan outdoor activities during dusk and dawn hours when mosquitoes are most active.

"Oh no. We wouldn't do an outing at that time. We take that into consideration when planning the outings. During this time of year, we usually go to the movies and shopping. We have indoor outings."

If residents do go outside, repellent is used, she said.

The Department of Health reports that last year, there were 28 human cases of the virus in Florida, including two deaths. There were no cases of the virus in Charlotte County and two cases in Sarasota County. Roberts said one case was contracted inside Sarasota County and the other was acquired in another county on a camping trip and brought back to Sarasota.

DeSoto County has never had a case of West Nile, said Public Health Administrator Donald Toews. "We've don't have a problem," he said.

Collier Has First Case

Though West Nile cases normally peak between August and October, Collier County had a sentinel chicken test positive for the virus last week, the first case this year in Collier.

Nationwide, only Florida and North Carolina have had sentinel chickens test positive in 2003, according to the Centers for Disease Control. So far, Florida has had 35 sentinel chickens infected. Neighboring Lee County leads the state to date, with nine positive test results. Sarasota has reported two cases.

There are other indicators of West Nile, however, and as of last week, 16 states are on the CDC map for positive cases. Cases have been confirmed in Alabama, Florida, Georgia, Illinois, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, New Jersey, New York, North Carolina, Pennsylvania, South Carolina and Wyoming.

In 2002, more than 4,000 people throughout the United States had symptoms of the virus and 284 died. Hardest hit was Illinois, with 884 cases and 64 deaths. The first confirmed case in the U.S. was in New York in 1999. The first in Florida occurred in 2001 in Tallahassee. No human cases have been reported this year as mosquito season gets underway nationwide.

Since first appearing in the U.S. in 1999, West Nile also has seriously impacted bird populations. Crows and blue jays have been especially hit hard.

Julie Harter, a curator for Sarasota Jungle Gardens, said birds of prey at her establishment are annually vaccinated against the disease. There also is a vaccine for horses.

Chickens Are Sentinels

Sentinel chickens, which can be carriers of the virus, are widely used in Florida as test birds. In Charlotte County, chickens are placed in nine different locations throughout the county. Three chickens are kept in each area and blood is drawn and tested weekly to see if a chicken has been infected by a mosquito. Sarasota County also uses them. Toews said sentinel chickens will be placed in strategic areas in DeSoto County in August.

Day also has 15 traps scattered throughout Charlotte County to determine mosquito populations. When numbers get too high in one location, the area is sprayed with pesticides. Day said both airplanes and trucks are used to spray. The trucks spray a chemical called Permanone 3166 and the planes spray Dibrom.

Sarasota County uses those same chemicals to control mosquito populations but also uses a liquid larvaecide that attacks mosquito eggs but does not hurt fish or birds. They use this method extensively as summer heat speeds up the insect's life cycle.

"When it gets warmer, the mosquito can go from a larvae to a flying, biting adult in a week," Roberts said.

Both counties already have begun spraying.

Areas where fish swim are not normally sprayed with chemicals in order to protect the health of the fish and waterways. Fish feed on mosquito larvae, which controls mosquito populations naturally.

Other areas, where fish do not frequent, such as water retention ponds or roadside swales, are sprayed.

The plane is used only when the "numbers get so high" in certain areas and in regions that spray trucks can't access, Day said.

Even though the experts are careful, some people, like those with asthma or people with organic farms, don't like to have the sprays used near them. Day and Roberts have a list of these people, and their homes and farms are avoided by trucks and planes.

"In mosquito control we are always looking for better ways of doing things," Day said. She's been in Charlotte County for seven years and has seen her department try several methods of mosquito control, such as using different spray pressures and varying speeds. New chemicals also have been tried.

Sarasota Uses New Test

Sarasota County workers have new technology they are trying this year to test for West Nile. They are using resting traps in specific testing areas, Roberts said, to trap the insects during the hot afternoon hours when the insects don't swarm. The traps are collected, the mosquitoes are ground up and a type of litmus test is used on the bugs to see if they are carrying West Nile.

There are ways people can discourage mosquitoes from taking up residence near a home.

Mosquitoes breed in ponds, brackish and fresh water. They also breed in kiddie pools, bird baths and buckets in people's yards. "They are very opportunistic," Day said.

For people with backyard ponds, Charlotte County is planning to offer free mosquito fish or gambusia, that will eat the larvae when the fish are placed in the pond. Day said that program should be up and running by August.

Sarasota County already has such a program. "We deliver mosquito fish to people who call us," Roberts said. The county also places the 3-inch fish in water retention ponds throughout the county to help control insects.

In addition, the experts say, people should stay indoors at dusk and dawn, and wear long sleeves and pants when outdoors. They advise using insect repellent that contains DEET.

In other words, don't follow Day's example.

You can e-mail Carie L. Call at clcall@sun-herald.com.

Copyright © 2003 Sun Herald, a division of Sun Coast Media Group Inc. Publishers of the Sun newspapers.

This article posted June 11, 2003.