Area researchers are focusing on chemicals that may be more effective than DEET.
Gainesville researchers are testing the next generation of mosquito repellents, although that might be little comfort to local residents if warm and wet weather brings a new wave of the insects.
Researchers at the University of Florida and U.S. Department of Agriculture are focusing on seven chemicals that appear more effective than the common repellent DEET.
Volunteers test the chemicals by wearing a plastic sleeve with an opening where a treated or untreated patch is placed.
They then stick their arms inside a cage filled with 500 mosquitos.
"It's great when the repellents are working," said Ulrich Bernier, a research chemist with the agriculture department.
"If it fails, you're going to notice."
Bernier said the chemicals are being developed for the military and it could take years before they hit the civilian market.
In the meantime, Alachua County residents will have to stick with DEET and other methods to deter mosquitoes. A recent discovery of a fatal mosquito-borne disease provides extra incentive to do so.
Eastern Equine Encephalitis - or EEE - has been detected in a horse and chicken in Alachua County this month. The disease is rare in humans but kills one-third of those infected, making it one of the most deadly mosquito-borne diseases in the U.S.
"It just underscores the fact that we need to take precautions to avoid being bitten by mosquitoes," said Paul Myers, assistant director of the Alachua County Health Department.
The county experienced a significant upturn in the number of mosquitoes found in traps in April, he said. He linked the increase to rainy weather during the month, which is expected to return in the coming days.
"It really raises the threat of mosquito-born illnesses," he said.
Florida had already experienced 17 cases of EEE by late April, an early time of year for that number of reports, said Roxanne Connelly, a mosquito-borne disease specialist at UF's Florida Medical Entomology Laboratory in Vero Beach.
The most active season for mosquitoes coincides with warm and rainy weather from May to October, she said, with the most cases of mosquito-borne diseases falling in July and August.
While the state has yet to see human cases of another deadly disease, West Nile Virus, there have been reports elsewhere. The Centers for Disease Control and Protection this month reported human cases in Arizona, Mississippi and Tennessee.
"It is a bit early, but I don't think it should be any cause for alarm," Connelly said.
She said Florida had seen a rash of West Nile cases before the 2004 hurricanes. But the reports tapered off after the storms, she said, perhaps because infected birds and mosquitoes were killed off.
Hurricanes can also benefit mosquitoes. Since Hurricane Katrina, the state has seen the first instances of a mosquito breed native to Central and South America.
Connelly said the breed first appeared in the Panhandle and has since moved east and south. It isn't clear whether the breed poses a particular threat for spreading disease, she said.
Myers said residents concerned about mosquito-borne diseases should follow the five D's: drainage, dress, dusk and dawn, and DEET. The first four refer to preventing standing water, wearing clothes that cover the skin and avoiding the outdoors when mosquitos are active.
DEET is the most common active ingredient in mosquito repellents. The chemical is effective but has drawbacks such as its smell, stickiness and softening effect on plastics, Bernier said.
A malaria-transmitting mosquito species found abroad has also shown a resistance to DEET, he said. The U.S. Department of Defense is funding Bernier's research into chemicals that might work better in the field.
The research is focusing on seven chemicals shown to be the most effective repellents that are also cost-effective.
The chemicals are related to the active ingredient in peppers.
Researchers are comparing the repellents with DEET and an untreated control. Big red blotches of bites on the arms of volunteers provide evidence of their work.
Bernier said the most effective of the new chemicals has shown to last 73 days at high doses - over three times longer than DEET.
A person could spray themselves with the repellent and be assured it would last until the next time they shower, he said.
The military will first use the repellents, he said, which could require years of tests before being sold commercially.
He said the repellents could join the Internet and geographic information system technology as widely used innovations first developed for the military.
"Normally when we do things for the military, we benefit in the public sector," he said.
Nathan Crabbe can be reached at 352-338-3176 or crabben@gville sun.com.