World Mosquito Day, August 20
August 20 is World Mosquito Day, commemorating the discovery of Sir Ronald Ross who first showed that female mosquitoes transmit malaria.
Balintfy: Malaria is caused by a single-celled parasite, but infection in humans is a result of transmission by mosquitoes.
Costero: Mosquitoes are important vectors of diseases to humans.
Balintfy: Dr. Adriana Costero is a Vector Biology Program Officer at NIH. And what is a vector?
Costero: It’s basically an animal that helps transmit pathogens from one human or one animal to another.
Balintfy: In the case of mosquitoes, they are vectors for a variety of diseases.
Costero: Malaria, dengue, yellow fever, West Nile virus, those are all mosquito-borne disease.
Balintfy: Malaria in particular kills nearly one million people each year; there are roughly 300 to 500 million cases annually; and more than 40 percent of the world’s population lives in areas where there is a risk of contracting malaria. So a great deal of research is going on to better understand mosquitoes and how to prevent the spread of pathogens like malaria. Dr. Costero highlights two studies which are using new approaches to controlling disease transmission and mosquito populations.
Costero: Both approaches have resulted not only in the pathogen not being able to be transmitted but also in killing the mosquito. So at the same time you’re preventing transmission, you’re also reducing the population of mosquitoes which could have an impact.
Balintfy: One study, conducted by Dr. Roger Miesfeld, an NIH-funded researcher at the University of Arizona, focused on a molecular process involved in the mosquitoes’ digestive system. He says when a cellular process known as vesicle transport was blocked, the mosquitoes couldn’t digest their blood meal.
Miesfeld: Which wasn’t a good sign for the mosquito. And by the next day, half of them were dead; and by the third day, all of them were dead.
Balintfy: This premise of killing the mosquito after it bites one person and before it can infect another is similar to a study conducted by NIH-funded researchers at Colorado State University. Dr. Brian Foy looked at treatments to whole villages in Southeastern Senegal with a drug typically used to treat infection with various worms. He says there may be a potential for controlling malaria transmission with the same medication.
Foy: We were collecting mosquitoes before and after treatments and determining their survival rates; and when we did that, we saw a significant drop in the mosquito survival.
Balintfy: While both these studies show promise, Dr. Costero reminds that more research is needed.
Costero: This research is at a very early stage, especially Dr. Foy’s research. But he has found evidence of something very interesting so he’s going to pursue that. Now Dr. Miesfeld has found something that also is at the early stages because there are always more questions that need to be resolved in order to translate this kind of discoveries into some sort of intervention. That’s going to take a lot of years but the first step obviously is to find something that seems to be useful to prevent transmission or to bring mosquito populations down.
Balintfy: For more information on mosquitoes, malaria and this research, visit www.niaid.nih.gov. And to hear more from Drs. Costero, Foy and Miesfeld, listen to episode 140 of the NIH Research Radio podcast. This is Joe Balintfy, National Institutes of Health, Bethesda, Maryland.