Experts find way to make mosquitoes dengue-free

HONG KONG,  (Reuters) – Injecting a bacteria into  mosquitoes can block them from transmitting the dengue virus and  help control the spread of a disease that kills 20,000 annually  in more than 100 countries, scientists said.

In two papers published in the journal Nature on Thursday,  researchers in Australia showed how female mosquitoes infected  with the Wolbachia bacteria passed the bug easily to their  offspring, making them all dengue-free.

They said such infected mosquitoes should be released into  the wild, so that the spread of dengue to people may be reduced.

“The main feature we saw was their ability to reduce dengue  transmission,” said Professor Scott O’Neill, lead author and  science faculty dean at Monash University. “It almost completely  abolished dengue virus in the body of the mosquito.”

In their experiment, O’Neill and colleagues injected the  bacteria into more than 2,500 embryos of so-called Aedes aegypti  mosquitoes that can spread dengue fever. After they hatched,  they were treated to blood meals laced with the dengue virus,  and none picked up the virus.

“The (Wolbachia) bacteria doesn’t spread environmentally, it  gets passed on from mother to children through the eggs,”  O’Neill told Reuters by telephone.

“When an infected male mates with an uninfected female, all  her eggs die. That gives an indirect benefit to the females with  Wolbachia because when they mate with infected males, their eggs  hatch normally … all their eggs have Wolbachia in them so  Wolbachia gets more and more common with every generation.”

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