New research confirms what many scientists have theorized: a bacteria could help control the spread of the Zika virus. Researchers infected mosquitoes with a bacteria called Wolbachia and released them to mate with non-Wolbachia-infected mosquitoes in the wild, and then measured levels of the Zika virus in the mosquitoes. Over a few generations, the virus levels dropped and became inactive, which means those mosquitoes cannot transmit the Zika virus to humans.
The idea to use Wolbachia-infected mosquitoes to control Zika virus outbreaks is based in common sense. The mosquito vector Aedes Aegypti which carries the Zika virus is also responsible for spreading malaria, dengue fever, and yellow fever. Previous trials using Wolbachia to reduce dengue fever seemed promising, spurring scientists in Brazil to try it out on in Zika hotspots, where thousands of children have been born with microcephaly, a birth defect resulting in an abnormally small head and brain.
Male mosquitoes are infected with the Wolbachia bacteria and then released to mate with non-Wolbachia females. That union results in infertile eggs in female offspring, so after a few generations, the number of disease-carrying mosquitoes falls dramatically. The bacteria is passed on from generation to generation, translating into a long-term strategy for reducing the number of disease-carrying mosquitoes in regions where the infected males are released.
“Zika and dengue belong in the same family of viruses, so with the outbreak in Brazil, the logical idea was to test the mosquitoes carrying Wolbachia by challenging them with Zika virus,” said senior author Luciano Moreira, Ph.D., of the Oswaldo Cruz Foundation in Rio de Janeiro, in a statement. “Wolbachia showed to be as effective on Zika as the most important dengue experiments we did.”
This research, published online May 4 in Cell Host & Microbe, supports the efforts of the world’s largest “mosquito factory,” located in China, where concerns about mosquito-borne illnesses are elevated in rural towns. There, some 20 million Wolbachia-infected male mosquitoes are being released in strategic areas each week, in an effort to slash disease transmission rates. Because mosquitoes have a short life span, it only takes a few months to see the impact over several generations of the bitey little bugs.