The smaller the mozzie the nastier the bite

Nov 10 2008

Experts have found that the smaller the mosquito the more likely that it is infected with viruses which cause human diseases.

American entomologists have discovered that smaller-sized mosquitoes had more infections and more potential to transmit Dengue virus than larger individuals.

Dr Barry Alto, Director of the Medical Entomology Program at the Illinois Natural History Survey, Assistant Professor Michael Reiskind of Oklahoma State University and Professor L. Philip Lounibos of the University of Florida fed mosquitoes blood with Dengue virus and later tested them for infection.

The research which was carried out at the Florida Medical Entomology Laboratory, took into account the size of each mosquito by measuring the length of their wings - however, Dr Alto says other components, such as adult longevity, host preference, and feeding frequency, also determine a mosquito's vectoring ability which still need to be taken into account in future studies.

The two main transmitters of the Dengue virus are the Asian tiger and yellow fever mosquitoes - Dengue is the mosquito-borne virus of greatest importance to human health.

Both of these mosquitoes are found throughout the world and now the researchers have shown that only slight differences in the body sizes of these mosquitoes significantly change their potential to transmit viruses causing human disease and, surprisingly, the effects were consistent for the two species of mosquito.

These results could have important implications for mosquito control strategies and evaluation of disease risk for dengue.

Competition among the larvae of container-breeding mosquitoes results in smaller sized adults, however, control strategies such as larvacides, release surviving larvae from competition.

This means control strategies which lead to larger, less competent adult mosquitoes could in terms of infection and potentially mitigating dengue transmission - be a benefit.

The results have the potential to provide information on disease risk and help in control efforts of the diseases that mosquitoes transmit.

The Medical Entomology Program of the Illinois Natural History Survey was developed out of concern for container mosquitoes but has recently invested much of its efforts towards addressing West Nile virus as well as a program on encephalitis prevention.

These research is published in the November issue of the American Journal of Tropical Medicine and Hygiene.