In a completely different kind of germ warfare, researchers have tried dropping mosquitoes infected with disease-fighting bacteria onto populations prone to dengue outbreaks—an ingenious way to scale up a proven solution.
While dispersing infected mosquitoes via drones may seem like a malicious way to spread disease, a recent study that did just that found that this approach can do the opposite. That's because the mosquitoes used Wolbachia Bacteria that inhibit the virus that causes dengue fever, a painful infection that affects 390 million people each year, according to the World Health Organization.
The strategy of introducing modified mosquitoes is proving to be an effective way to combat the diseases they spread. For example, we have seen mosquitoes genetically modified to stop the growth of malaria parasites in the insects’ guts, resistant to four types of dengue virus, and having lost the ability to sniff out humans as a source of blood meals.
But releasing modified mosquitoes into the wild can be difficult, and to date most approaches have relied on humans to release them on the ground, which can involve crossing difficult and potentially dangerous terrain. Earlier this year, we saw drones used to deliver sterilised mosquitoes in Brazil, and now a study led by Ya-Hsun Lin of the World Mosquito Programme (WMP) in Melbourne, Australia, has used a similar approach. WMP is the organisation that pioneered the approach. Wolbachia-based method to prevent the spread of dengue fever.
The drone-based mosquito delivery system designed by Lin and his colleagues has the capacity to carry 160,000 adult mosquitoes. The insects are attached to the drone in a temperature- and humidity-controlled chamber where they remain healthy but sedated until the drone reaches the delivery site. At that point, the mosquitoes are released in groups of 150 as the drone flies, dispersing the insects over a wide area.
In two field tests conducted in Fiji, Lin and colleagues report that the delivery method was as successful as land-based releases, but in this case mosquito dispatchers were able to operate the drone from a safe, remote location rather than entering dense forest. The second of the two tests showed that the released mosquitoes Wolbachia– Inhibition of wild bacterial populations in an area of two square kilometers (about 0.8 square miles).
WMP has already shown that releasing Wolbachia-infected mosquitoes into the wild in Indonesia has led to a 77% reduction in the spread of dengue fever. With the disease having increased in cases 30-fold in the last 50 years, the new combined drone/mosquito method offers real hope for those affected when applied to new areas each year.
The study, which explains the method in detail, was published in the journal Science Robotics.
Source: American Association for the Advancement of Science via EurekAlert