FRIDAY, May 10, 2013 — In the ongoing battle against malaria, bacteria may be our secret weapon, according to a study published recently in the journal Science.
Although mosquitoes don't become infected with malaria, they can carry the parasite around, where it reproduces in their stomachs. The bacteria Wolbachia acts as a vaccine against malaria in mosquitoes and not only stops the parasite from reproducing, but also stops them from spreading the parasite to humans. The findings, researchers said, could help stop the deaths caused by malaria worldwide every year.
"Wolbachia-based malaria control strategy has been discussed for the last two decades," Zhiyong Xi, study author and assistant professor of microbiology and molecular genetics at Michigan State University, said in a statement. "Our work is the first to demonstrate Wolbachia can be stably established in a key malaria vector, the mosquito species Anopheles stephensi, which opens the door to use Wolbachia for malaria control."
Wolbachia commonly infects insects, not humans, and is passed from females to their offspring, researchers said. The bacteria spread quickly throughout mosquito populations, according to the study, which means that it may only have to be applied once.
"We developed the mosquito line carrying a stable Wolbachia infection," Xi said. "We then seeded them into uninfected populations and repeatedly produced a population of predominantly Wolbachia-infected mosquitoes."
This technique, though still years away, is promising, said Johanna Daily, MD, professor of medicine and microbiology & immunology at Albert Einstein College of Medicine. In areas of the world where malaria is prevalent, such as Africa and Southeast Asia, they use pesticides to kill mosquitoes. However, the pesticides are becoming less effective, she said.
“The problem with spraying pesticides is that mosquitoes have become resistant in many areas,” she said. “We have a few different kinds of pesticides, but not enough to keep up with how fast the mosquitoes are adapting.”
The problem of resistance, she added, would likely be eliminated if Wolbachia is used.
“It’s unlikely that mosquitoes will be resistant to bacteria because it’s not killing them,” Dr. Daily said.
Malaria is a big problem in parts of the world, and despite attempts at using bed nets and spraying to prevent it, malaria continues to kill hundreds of thousands of people every year. Using the bacteria could be a safe and effective way to help bring the infection rate down, Daily said.
“There area of the world where malaria is very endemic,” she said. “People there may have hundreds of infectious bites every year. We have a good sense of where these areas are, but it’s been hard to get the transmission rate down. This should help.”