County has first human WNV case

Published 5:00 am Tuesday, April 1, 2008

The Mississippi State Department of Health confirmed Monday thatthe first human case of West Nile virus in the state this year hasbeen reported in Lincoln County.

Details about the patient and other aspects of the case were notdisclosed. Also, the Lincoln County case is only the second humancase reported in the nation for 2008.

“This just means we’ve got West Nile in that area, and likelyit’s in other areas of the state, too,” said State EpidemiologistDr. Mary Currier.

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Although a March case of West Nile virus is atypical, as theseason for the virus extends from mid-summer through fall, Curriersaid cases have been reported as early as January and as late asDecember.

“It can happen at any time of the year,” she said. “Mosquitoescan be around at any time of the year, and we all need to takeprecautions.”

Four people died as a result of the virus in 2007, with 136total reported infections. Currier said the number of infectionsreported last year, and possibly this year, may be more, since only20 percent of the people who are infected with West Nile virusactually display the symptoms.

“For every case we have reported, there are at least four othersthat go unreported,” she said.

Those who have battled the virus before need not worry, ashaving a West Nile infection once develops an immunity. Foreveryone else, Currier stressed taking precautions such asprotective clothing, mosquito repellent and, most importantly,eliminating mosquito breeding places by removing sources ofstanding water.

“It’s the little puddles more than the big ponds,” she said. “Wedon’t have an increase in West Nile cases around the reservoirevery year – it doesn’t breed mosquitoes.”

Currier said mosquitoes breed mostly in smaller sources of stillwater, like small ponds and ditches and any overturned container orcrevice that catches water.

“Get rid of those containers,” she said. “Places wheremosquitoes breed are usually small puddles that don’t move and havea lot of organic material in them, like old vegetation. It’s thelittle puddle in the tire swing, in the bird feeder – that standingwater in the ditch.”

Currier recommended declaring biological warfare on mosquitobreeding pools with a product called mosquito dunks, which canpurchased at feed stores.

Mosquito dunks, while in the water, slowly release a biologicalmosquito larvaecide composed of the bacteria Bacillus thuringiensissubspecies israaelenses (BTI). BTI remains active in the water for30 days, killing mosquito and black fly larvae before theyhatch.

It is recommended to use one mosquito dunk per 100 square feetof water.

“It’s an ecologically sound bacteria – it doesn’t hurt frogs,fish or other bugs,” Currier said. “You just throw them in thewater and they dissipate on their own. You can even throw them downthe storm drain and into sewers.”

Currier said mosquito dunks were more effective than usinginsecticide to kill adult mosquito.

“Spraying is not the most important piece,” she said. “Mosquitodunks decrease the mosquito population before it matures.”

Dr. Jerome Goddard, the state entomologist, said such larvaeciteprograms were the most effective means of combating mosquitoes on amunicipal level.

“Cities and counties may elect to start a mosquito controlprogram,” he said. “What we would emphasize here at the healthdepartment is larvaeciting – killing mosquitoes when they’re stillin an immature form, all concentrated in one small place.”

Goddard also recommended that municipalities tackle the mosquitoproblem with education.

“Educational materials can be put out through various avenues,”he said. “You can put them in the water bill and mail them out soit doesn’t cost extra postage. We’ve seen towns do thatoccasionally.”

Clean-up days are another important method of combatingmosquitoes. Disposing of artificial mosquito breeding pits likecans and tires is an important part of limiting mosquitopopulations and preventing the spread of West Nile virus.

“Most small towns have a clean-up day every now and then,”Goddard said. “Emphasize the junk along the highway – artificialcontainers like bottles and potato chip bags. Mosquitoes breed inthat stuff.”

The Mississippi State Department of Health has a list ofinformation regarding the West Nile virus, personal protection andmosquito population reduction online