Infect a mosquito with a bug, to stop it from spreading diseases in humans? Sounds like science fiction at its best, but it is already reality: Humans could be protected from dengue fever by infecting the mosquitoes carrying it with a parasite which halves their lifespan. Wolbachia – a kind of bacteria – spreads well through laboratory-bred female aedes aegyptii mosquitoes, which spread dengue fever and yellow fever. The virus is passed to humans when mosquitoes carrying it feed on their blood, and while there have been efforts to eradicate them using insecticides, these have been fraught with problems, including the ability of the mosquito to become resistant to the chemicals used. The bacteria can be passed from infected female to offspring, and even though the cost in terms of lifespan should mean that infected insects should die out, Wolbachia has another trick up its sleeve. It makes subtle changes to infected males which mean they can only produce offspring with infected females. __
