Small Things Considered

No summer evening outdoors seems complete without a mosquito bite (or ten). While these bites are often just a nuisance, they can also serve as the point of transmission for many mosquito-borne diseases: West Nile virus, dengue virus, yellow fever virus, malaria, and the filarial nematodes that cause elephantiasis, to name a few. Efforts to control the spread of these diseases, many of which cannot be curbed by vaccination, have lately looked to the intracellular bacterium Wolbachia pipientis for help. Wolbachia naturally infect many insects including some mosquitoes, and strains have recently been developed to infect Aedes aegypti, the vector for dengue, and Anopheles gambiae, malaria's vehicle of choice. Infection by Wolbachia may limit the spread of these diseases by efficiently becoming established in insect populations, where they shorten the lifespan of their hosts or directly interfere with the pathogens the insects carry.