No AIDS via mosquitoes.

No AIDS via mosquitoes

The high incidence of AIDS in Belle Glade, Fla. -- in the range of what is occurring in Manhattan and San Francisco -- cannot be attributed to transmission of the AIDS virus by mosquitoes, according to a study by the Centers for Disease Control (CDC) in Atlanta and the Florida Department of Health and Rehabilitative Services.

Researchers from the Pasteur Institute in Paris recently reported finding AIDS-virus-like segments in the chromosomes of mosquitoes, tsetse flies, cockroaches and other insects. That information, they concluded, suggests that insects could be reservoirs of the virus and strengthens the possibility of insect-borne transmission.

But a CDC study of the 62 people diagnosed with AIDS in Belle Glade between July 1982 and mid-September 1986 shows no evidence of mosquito transmission. The CDC and Florida researchers analyzed the risk factors among the 62, surveyed 736 townspeople to see who had antibodies to the virus, and checked both the sick and healthy groups for evidence of exposure to mosquitoes.

Eight of the 62 people with AIDS had no known risk factors, but six of those had died before they could be questioned. Looking at the incidence of antibodies to the virus in the general Belle Glade population, the researchers found no antibody-positives over 60 years old or between the ages of 2 and 10. And checking for antibodies to other mosquito-borne viruses, they found no difference between antibody-positive and antibody-negative people.

Given the age disparity in infection, the lack of a relationship between mosquito exposure and infection, and the fact that most of the "no known risk factor" group had never been interviewed and could very well have had risk factors, mosquito transmission in Belle Glade is not likely, the researchers say. "If you look at all the data, you have to conclude there does not seem to be any evidence to suggest the AIDS virus is being transmitted by insects," says Kenneth G. Castro of the CDC's AIDS Program Office.