In a completely different kind of germ warfare, researchers have tested out a way to drop mosquitoes infected with disease-fighting bacteria over populations prone to outbreaks of dengue fever. It's an ingenious way to scale up a proven solution.
While distributing infected mosquitoes via drone might sound like a nefarious way to spread disease, a recent study that did just that found that the approach can do exactly the opposite. That's because the mosquitoes used were infected with the Wolbachia bacteria, which blocks the virus that causes dengue fever, a painful infection that afflicts 390 million people every year, according to the WHO.
The strategy of introducing mosquitoes that are somehow altered is proving an effective way to combat the diseases they spread. For example, we've seen mosquitoes that have been genetically engineered to stop the growth of malaria parasites in the bugs' guts, resist all four types of dengue virus, and lose their ability to sniff out humans as a source of blood meals.
But getting the modified mozzies into the wild can be a challenge and, to date, most approaches rely on people releasing them on the ground, which can involve driving through difficult and potentially dangerous terrain. We did see the use of drones in spreading sterilized mosquitoes in Brazil earlier this year, and now a study led by Ya-Hsun Lin from the World Mosquito Program (WMP) headquartered in Melbourne, Australia, has used a similar approach. The WMP is the organization that pioneered the Wolbachia-based method to fight the spread of dengue.
The drone-based mosquito-delivery system engineered by Lin and his colleagues has the ability to carry 160,000 adult mosquitoes. The insects are attached to the drone in a temperature- and humidity-controlled compartment to keep them healthy but sedated until the drone reaches the distribution zone. At that point, the mosquitoes are released in groups of 150 as the drone flies, in order to broadcast the bugs over a wide range.
In two field tests carried out in Fiji, Lin and his colleagues report that the distribution method was as successful as ground-based releases, but in this case, mosquito dispatchers were able to operate the drone from a safe remote location, rather than needing to drive into the thick jungle. The second of the two tests confirmed that the released mosquitoes were able to spread the Wolbachia-blocking bacteria to the wild population over a two-square-kilometer (about 0.8-square-mile) area.
The WMP has already demonstrated that deploying Wolbachia-infected mosquitoes into the wild in Indonesia resulted in a 77% reduction in the spread of dengue. With the disease now having seen a 30-fold spike in cases in the past 50 years, the new combined drone/mosquito method holds out real hope for those afflicted annually as it is rolled out into new areas.
The study detailing the method has been published in the journal Science Robotics.
Source: American Association for the Advancement of Science via EurekAlert
