Infecting Mosquitoes with Bacterium Could Slow the Zika Virus

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In the fight against the spreading Zika virus, scientists have uncovered an unlikely ally in the form of a bacterium called “Wolbachia.” The Aedes aegypti mosquito, the more abundant of the two species known to spread the Zika virus, are less able to spread the virus if they are exposed to the bacteria, according to a study published Wednesday in the medical journal Cell Host & Microbe.

The bacteria are already being used on the same mosquitoes as a way to curb the spread of the dengue virus, which, like Zika, is a flavivirus. Mosquitoes containing this bacterium did not become infected with the Zika virus when given saliva from other infected mosquitoes, researchers from the Rene Rachou-Fiocruz Research Center in Brazil discovered.

When they conducted the same test in mosquitoes without the Wolbachia bacteria, approximately 85% of mosquitoes became infected with the Zika virus.

“The results presented here indicate that (Wolbachia-infected mosquitoes) represent a realistic and effective option to combat the (Zika virus) burden in Brazil and potentially in other countries and should be considered as an integral part of future control efforts,” the authors concluded.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center (Nashville TN), said that experimental treatments like this one may be key to stopping the Aedes aeygpti mosquito, which is notoriously hard to eradicate.

The Aedes aegypti mosquito can live indoors and bite during the day, Schaffner noted, making it extremely difficult to kill with normal outdoor spraying. Spraying may need to be used with other experimental treatments, including using genetically modified mosquitoes, to cut down on the population, he said.

“If you look realistically at what we have currently available in all of our local municipal public health jurisdictions, funding for mosquito abatement, it varies enormously from municipality to municipality,” Schaffner said. “It’s focused on nuisance mosquitoes and not disease-causing mosquitoes and Aedes (aegypti) is much more tenacious,” than other mosquito species.

More information is needed about the feasibility of infecting the mosquitoes with the bacteria, since the cost and technology needed may make it impractical outside of a lab setting, Schaffner said.

Meanwhile, Spain has recorded its first case of a fetus developing the microcephaly birth defect after a pregnant woman became infected with the Zika virus, health authorities said late on Thursday. Spain has recorded 13 expectant mothers who have contracted the virus after traveling overseas, though no others are known to have developed defects.

The mosquito-borne Zika virus has been linked to hundreds of cases of microcephaly in countries such as Brazil, which has declared a public health emergency over the disease.

Monday, May 9, 2016 / Vol. 24 / No. 18