In a Life Sciences Annex lab, graduate student Andrew Mackay extracted blood from the abdomens of 1,100 mosquitoes that he collected over a two-year period in East Baton Rouge Parish. Mackay and associate professor of entomology Wayne Kramer are researching West Nile virus as mosquito season approaches. They use sophisticated molecular techniques to identify the types of DNA found in the blood samples. “I’m looking at the characteristics of mosquitoes to determine which species are important, host-seeking behaviors and seasonal distribution,” Mackay said. Mackay said he is still in the process of detecting live infectious West Nile virus in the blood samples, but the rates have been low so far. He said the East Baton Rouge Parish Mosquito Abatement and Rodent Control test mosquitoes for dead infectious West Nile virus, so they detect much higher rates of the virus. Kramer said they are also researching how mosquitoes carry and transmit West Nile, how mosquitoes maintain the virus, which species of mammals or birds host the virus and what effects bird migration patterns have on the spread of West Nile. “We’re trying to understand the cycle of the virus in nature,” Kramer said. The research project is titled “The Evaluation of Potential Vectors of West Nile in East Baton Rouge Parish.” “East Baton Rouge Parish is certainly one of the areas that has a lot of activity,” Mackay said. Kristen Meyer, Louisiana Department of Health and Hospitals public information officer, said the vector-borne disease is transmitted to humans from mosquitoes that have previously bitten an infected bird or mammal. Rather than developing the virus, the mosquito becomes a carrier and spreads the virus to other sources. Kramer said West Nile first appeared in the United States in 1999 when New York state reported 62 human cases to the Centers for Disease Control and Prevention. Connecticut, New Jersey and Maryland reported carrier mosquitoes as well as infections in birds and mammals. In 2001, Louisiana reported its first human case of West Nile to the CDC. The most human cases in Louisiana were reported in 2002. There were 329 reported cases that year and the virus was responsible for 25 deaths. Louisiana’s reports of human cases declined to 124 with eight deaths in 2003 and 109 cases with seven deaths in 2004. Meyer said the diminishing number of cases in subsequent years is a national pattern. Last year, there were 171 human cases with 11 deaths in Louisiana, but none have been reported so far this year. Meyer said reports of West Nile usually start to appear in mid-July. “Even if there hasn’t been a recent human case in a parish, that doesn’t mean that the virus isn’t there because it is transmitted by mosquitoes,” Meyer said. Meyer said East Baton Rouge, Caddo, Bossier and Livingston Parishes have reported the most cases of West Nile in the past three years. “West Nile is statewide,” Meyer said. “In the past, every parish has had either a human case or detected it in mosquitoes.” Kramer said most people who contract West Nile experience mild flu like symptoms or headaches, but most people don’t feel any symptoms at all. A small percentage of people with the virus develop severe encephalitis or meningitis. He said responses to West Nile are variable, depending on age and previous health conditions. “With bacteria, you can give an antibiotic, but viruses are not easy to treat,” Kramer said. Meyer said she advises people to take extra precautions when the virus is most active. She said using repellant, wearing protective clothing, draining standing water as well as repairing torn screen doors and broken windows will help reduce the risk of contracting West Nile. She said people who experience symptoms associated with West Nile should contact their physician. Kramer said mosquito populations are lower because it has been a dry summer, but this should not be an indication that the virus isn’t around. “Take precautions,” Kramer said. “The virus is just starting to become active right now.”
—–Contact Angelle Barbazon at [email protected]