UA GRADUATE STUDENT COMPLETES MOSQUITO SURVEY

FAYETTEVILLE, Ark. - None of the 14,560 mosquitoes collected by a University of Arkansas graduate student last summer carried West Nile virus or any other disease-causing virus that could be transmitted to humans.

But West Nile virus killed four birds scattered around the state last September, so not finding it in the relatively small sample of mosquitoes clearly doesn't mean the virus hasn't reached Arkansas.

"Finding a mosquito that is actually carrying a virus is like looking for a needle in a haystack," said Rebekah Crockett of Frederica, Del., who has completed work this spring on a master's degree in entomology in Bumpers College of Agricultural, Food and Life Sciences.

The survey, part of Crockett's master's thesis research, was funded in part by a grant from the Center for Disease Control to the Arkansas Department of Health. "The Department of Health wanted to determine the potential for West Nile virus and other mosquito-transmitted diseases in Arkansas," she said. "One of the big reasons behind the grant has been the rapid spread of West Nile."

West Nile virus first appeared in this country in New York City in 1999. "It was reported in 12 states in 2000," Crockett said. "In 2001, 27 states have reported finding the virus."

The survey also looked for signs of the viruses that cause St. Louis encephalitis and eastern equine encephalitis, mosquito-transmitted diseases that have occurred in Arkansas. St. Louis encephalitis is closely related to West Nile virus and has caused illness in people living in and around Pine Bluff. Although eastern equine encephalitis has affected humans in other states, it has occurred only in horses and emus in Arkansas.

Before coming to the U of A, Crockett worked two summers for the Mosquito Control Section of the Delaware Department of Natural Resources, Division of Fish and Wildlife.

Last summer, she concentrated on trapping mosquitoes in 10 counties where mosquito-transmitted viruses had been reported in the past or where the Department of Health determined they were likely to exist. Mosquitoes were also collected from nine other Arkansas counties. She used different kinds of traps designed to capture a variety of species.

"We identified 24 species," she said. "Culex mosquitoes, like the common house mosquito, were found widely around the state. It's a known carrier of West Nile virus in northern states, but no one has established it as a carrier in the South."

Crockett said the Department of Health will continue the mosquito surveillance, after she graduates in May, to try and determine which species carry West Nile in Arkansas. But birds are probably the best means of establishing the virus' presence in the state.

"Birds are believed to be the agent carrying the disease across the country," she said. "Their migratory patterns probably account for the speed at which it's spreading. It has been found in many different species, but the most common seem to be blue jays and crows. Anyone who finds a dead bird, with no obvious cause of death, should contact their county health department."

Crockett said people can prevent or reduce mosquito populations around their homes by eliminating standing water sources in which mosquitoes breed.

"Get rid of old tires or other things that can hold water, and make sure gutters are not clogged," she said. "Change the water in pet bowls or bird baths at least every five days to interrupt the insects' growth cycle."

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