Scientists at the University of California, Davis, are researching how to terminate some of humanity's deadliest foes -- disease-carrying mosquitoes.

In particular, the dengue virus, spread by mosquitoes, wreaks havoc with the public heath in tropical regions of the world. Epidemics are common in Southeast Asia. Dengue fever is an emerging public health threat in many South and Central American countries.

Thomas Scott, professor in the Department of Entomology and director of the Mosquito Research Laboratory, is currently developing DNA techniques to evaluate the risk of dengue outbreaks in certain communities. An article in the April 18 issue of the journal Nature profiled Scott's research in Thailand.

There he found that a dengue-carrying female mosquito may need many blood meals to reproduce successfully, compared with the single blood meal required by most other mosquitoes. This finding, confirmed by individually marking female mosquitoes and recapturing them around people's homes, sheds light on why dengue can persist even when very few mosquitoes are present. It also reveals that just a few infected mosquitoes or people are needed to jumpstart an outbreak.

Scott is developing techniques to evaluate the risk of dengue outbreaks in specific communities. Using DNA fingerprinting, he has been able to match the blood in captured mosquitoes' stomachs to DNA samples from villagers.

He is now using this technique to discover which segment of the population mosquitoes bite, how frequently, and how far they roam in search of a meal.

In another project in Peru, Scott's team is studying the connection between the dynamics of dengue transmission to the density of mosquito populations. Basic research such as this, he hopes, may provide clues that will allow public-health officials to predict an imminent outbreak.

"Our hope is that we can identify some fundamental principles that can be tested elsewhere," he said. "Predicting an epidemic before it happens might not help to stop it, but it could help health departments prepare to treat the youngest and most susceptible victims, and so prevent unnecessary deaths."