By: Nathaniel Wolf, Sabin Vaccine Institute

August 20^th is World Mosquito Day.  In 1897, Sir Ronald Ross looked at a mosquito under a microscope and saw that it looked really cool up close.  He declared August 20^th World Mosquito Day and said we should be nice to mosquitoes, if only one day a year. 

Not really.  What Dr. Ross discovered was the link between mosquitoes and transmission of malaria.  He declared World Mosquito Day so that people would become educated about the life cycle of malaria, and in 1902 he won the Nobel Prize in Medicine for it.   In spite of this discovery, today the disease continues to be a threat to approximately 2.85 billion people, afflicting 250 million people around the world and causing an estimated 1 million deaths annually.   

Dr. Ross’ discovery was made possible by another discovery some 20 years prior.  In China, Sir Patrick Manson discovered that the mosquito is a vector for lymphatic filiariasis (LF), a debilitating parasitic disease that currently afflicts about 120 million people around the world.   LF causes a range of symptoms including elephantiasis, hydrocele and extreme swelling of the scrotum.  The economic and social effects of this disease are enormous.  If you’ve ever read James Michener’s Tales of the South Pacific, wherein he talks about a man who, in order to walk, had to push before him a “rude wheelbarrow” in which “rested his scrotum, a monstrous growth that. . .weighed more than 70 pounds and tied him a prisoner to his barrow,” you probably thought Michener was taking poetic license.  He wasn’t.

The 2.85 billion at risk for malaria are also those most at risk from neglected tropical diseases.   As Alanna Shaikh pointed out in her entry on this blog yesterday, malaria “shares territory, climate, and even modes of transmission with NTDs.”  The clinical outcome of childhood malaria and malaria in pregnant women is dramatically higher when combined with one or more NTD, and there is evidence that even susceptibility to malaria is increased by NTDs.

Furthermore, according to an article published in 2008 in PLoS Neglected Tropical Diseases by Drs. Peter Hotez and David Molyneux, the anemia caused by malaria is increased dramatically when combined with an NTD such as hookworm disease, of which there are almost 200 million cases in Africa alone.  More than anything else, this anemia is what makes malaria and NTDs “diseases of poverty”—adults can’t work when they are very sick, and children can’t learn. 

There is good news out there.  In addition to the positive things mentioned by Ms. Shaikh, UK’s Department of International Development (DFID) states that 11 African countries are “approaching elimination” and Rwanda and Ethopia have seen a 50% decrease in malaria cases.  

The Malaria Vaccine Initiative, a program of PATH, is conducting late-stage clinical trials on a vaccine against malaria.  Also, Sabin Vaccine Institute’s Vaccine Development Program, in partnership with Malaria Vaccine Initiative and Johns Hopkins University’s Bloomberg School of Public Health, is working on the development of a very exciting “transmission-blocking” vaccine (yes, I said “exciting,” “vaccine,” and “development” all in the same sentence).  In other words, if a mosquito “bites” a person who has been inoculated with this vaccine, it may render that mosquito unable to infect any other person with the disease.    So maybe some year in the future on August 20^th we can all roll up our sleeves and stick out our arms and be nice to mosquitoes, if just for one day.

 Nathaniel Wolf is an Information Officer for the Sabin Vaccine Institute. He is a fan of the Washington Nationals and is currently working on his first screenplay.