RESEARCH AIMED AT MOSQUITO DISEASES

The Missouri and Illinois departments of health have initiated testing to ward off major outbreaks of mosquito-born disease this summer.

Illinois state entomologist Linn Haramis said state and local public health staff have taken blood samples from wild birds in some 30 Illinois counties, including Pulaski and Union, since mid-May. The counties are places where mosquito-borne diseases either have historically occurred or recently were confirmed.

Illinois officials also will conduct tests in Missouri counties like St. Louis and St. Charles that are near the Illinois border and have large population concentrations.

Missouri has activated a similar early-warning system that includes research being conducted by the virology lab at Southeast Missouri State University. Dr. Howard Pue, state public health veterinarian, said the university captures mosquitoes throughout the state and tests them for the types of diseases they may carry.

Both states are particularly concerned about mosquitoes carrying viral infections that cause inflammation of the brain, or encephalitis. An outbreak of St. Louis encephalitis in 1975 caused more than 50 deaths and hundreds of people to be sickened in Illinois and Missouri.

Since then, Illinois has had several scattered recurrences of the disease over the years. In particular, Southern Illinois has a long record going back to the 1930s of rare but periodic outbreaks of St. Louis encephalitis. In Missouri, there has been no confirmed case of the disease in humans for at least 10 years.

"That's the good news. The bad news is it can just turn on a dime. One year you might not have any. The next year you might have some or many," Pue said.

Both states take blood samples from wild birds because they carry the disease. Detection of virus antibodies of more than 5 percent in the blood samples indicates an increased risk of human infection. Reports of encephalitis in horses, which also are at high risk for infection by mosquitoes, will usually precede human outbreaks by one to two weeks.

"Every year the issue is while the mosquitoes are out there they can potentially carry the disease," said Haramis.

So far this year testing has produced largely negative results for diseases that could be a threat to humans. However, the second half of the summer will be of greater concern since the type of mosquito known to carry disease in this region prefers hotter, dryer weather.

Haramis said personal protection is the first line of defense against being infected. Wearing long, light-colored clothing is a simple way to ward off mosquito bites. Insect repellents and citronella candles also are effective.

Defoggers used in communities are least likely to be effective, Haramis said.

"Defoggers have a very short level of control," he said. "If towns are investing a lot of money in defoggers, they probably would be better suited to treat the roadside areas that are attracting sites for mosquitoes."

The best method of mosquito control is to rid property of stagnant water found in bird baths, ponds, flower pots, old tires and other places where mosquitoes might breed. Drainage ditches should be kept clear of grass cuttings and other blockage, and decorative ponds should have fish in them, whenever possible.

"Mosquitoes need standing water that doesn't have fish in it, so if you can do anything to revert that, more the better," said Haramis. "Homeowners can't do a whole lot themselves, but these are things they can take care of fairly easily."