The Fight Against Biting Insect Diseases

Could there be an end to such depilating and sometimes fatal diseases as Lyme, West Nile, Rocky Mountain spotted fever, Malaria and Dengue Fever? Transmitted by biting insects-such as a variety of mosquitoes and ticks- these diseases are viral, infectious or parasitical in nature and are problematic in every country around the world. With symptoms ranging from high fever, muscle and joint pain, headaches, skin rash, nervous disorders, chills and fever, there is also the chance of contracting encephalitis (fever and swelling in the brain).

The World Health Organization reports that disease caused by biting insects sicken more than 550 million people each year and global warming will put millions more at risk. Increases in rainfall, temperature, and humidity will enable disease-spreading insects to breed at much higher altitudes than before, greatly increasing the risk of infection from such biting pests. There is hope, however, in the form of new research from a team in Florida, an area plagued by biting insects.

The research was carried out by Ulrich R. Bernier of the U.S. Department of Agriculture's (USDA) mosquito and fly research unit in Gainesville, Florida. He, along with his colleagues, believes that they are on the path to finding a repellent that is superior to DEET, which was first developed in 1946 by and for the military. To date, DEET it is the best insect repellent on the market and has been since it was made available to the public in 1957. In this research, funded by the Defense Department, data on hundreds of chemicals collected over 50 years was rated from 1 to 5 on their ability to repel insects. The team then focused on what the most effective ones - the 5s - had in common; a type of chemical known as N-acylpiperidines, related to the active ingredient in black pepper. The 10 most effective chemicals were then narrowed down to seven, with eliminations based on toxicity concerns and high production costs.

They then conducted laboratory tests, which were done on the clothing (not on the skin) of volunteers. Results showed that some chemicals warded off bugs for nearly 3 ½ months compared to less than 3 weeks for DEET. Several of the new chemicals "were just phenomenal," said Bernier, a research chemist at the USDA, "I was so surprised."

Although it will probably be 4 to 5 years before the new repellents will hit the market, toxicology tests to check for skin irritation and other safety concerns will begin this summer. Again this research is being funded by the military, but any success is expected to benefit the general public as well.

"This definitely sounds like promising work," said Rudy Bueno, director of Mosquito Control for Harris County. "This will have to be followed up by some pretty extensive field studies. But if the field data confirms the lab data, then you've got a potentially great product." Their findings are published in a May issue of Proceedings of the National Academy of Sciences.