Biology professor raises potential flag on mosquito-borne virus

Although it hasn't hit Missouri yet, a virus transmitted by the Asian tiger mosquito remains a concern for a local biology professor and arborvirologist.

Asian tiger mosquitoes, which can transmit a virus called chikungunya, are a major pest in St. Louis and "definitely exist" in Cape Girardeau, said Dr. Christina Frazier of Southeast Missouri State University.

"We're looking down the road," Frazier said. "It has not happened in Missouri. This is not something that people need to worry a lot about."

However, the virus has caused an outbreak in the Caribbean and turned up in Florida and several other states.

The normal cycle for West Nile and St. Louis encephalitis, she said, is bird-mosquito-bird, because birds can create enough virus to infect mosquitoes, and if mosquitoes want variety, they can munch on a horse or human, she said.

In the case of chikungunya, if an infected mosquito bites a person, that person could produce enough virus to infect another mosquito that bites them, and that mosquito could infect another person.

"It eliminates the birds," Frazier said, which could help the virus spread faster.

The name "chikungunya" is derived from a native African dialect and means "man who is bent up" because of the extreme joint pain the disease caused when it was first identified. Fever also is a symptom, she said.

Asian tiger mosquitoes came to the U.S. in tires imported from Japan, although they originally bred in tree holes, Frazier said. The mosquitoes can breed in tires even a small amount of water, and they fly around during the day, not just at dawn and dusk.

Frazier recommends fixing window screens, applying mosquito repellent and wearing long sleeves. She said people should get rid of standing water in tires and dog dishes, for example. This will help eliminate the risk of chikungunya and other illnesses, such as West Nile virus, which Frazier said remains a concern.

Mosquitoes buzz off after the first killing frost in mid- to late October, according to climate data. "Some years, that's not been that long. Some years it's been very long. We usually get enough of a frost here at some point," Frazier said.

Beginning in 1994, Southeast Missouri State became the site of a statewide mosquito testing lab under an agreement with the Missouri Department of Health to conduct mosquito-borne virus surveillance. Under the partnership, county health departments from across Missouri sent trapped mosquitoes weekly during summer months to Southeast's Arbovirus Lab to determine whether the pests were carrying West Nile virus or St. Louis encephalitis.

Seven years ago, the lab quit testing mosquitoes collected locally and two years ago stopped training county health department officials to trap them when federal funding stopped. Funding started after the 1993 Mississippi River flood.

But Frazier's work with St. Louis County Vector Control continued. The county uses information from the lab's testing to concentrate its mosquito-control efforts, she said.

St. Louis County Vector Control will take over the work of the Arbovirus Lab on Aug. 1, when Frazier plans to retire from Southeast. Frazier will begin training staff on how to test for vector mosquitoes beginning this week.

rcampbell@semissourian.com

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