The WHO says that there are two methods of vector control for malaria. The first is insecticide treated bed nets and the second is indoor spraying with residual insecticides. This advice, particularly the first, has been headed by individuals and groups who aim to reduce the burden of a disease that killed nearly one million people worldwide in 2008. Economically, the WHO estimates that malaria can decrease the GDP of a nation by as much as 1.3%. From both an aid and development perspective, the elimination of malaria is of the utmost importance.
Some of the most popular stories that fill up the malaria section of Google News are about students who have raised money to provide bed nets in a country of choice. Often they involve a young person who is motivated after learning about the impact of malaria on the lives of people in Sub-Saharan Africa or India (though it is not only only prevalent in those two areas) and is able to raise a significant sum of money through a basketball tournament or coin collection scheme.
The idea is quite simple. Mosquitoes come out most often during the evening and morning. The times when people are sleeping. A fine net will keep the mosquitoes out. Treating it with insecticide, harmless to the people sleeping under but deadly to the mosquitoes, ensures that they are no longer a problem. Easy to use and cheap to produce, insecticide treated bed nets have been a cause around which many can rally.
Recently released research from Senegal shows that the story is not quite so simple. Published in The Lancet, the study ran by Dr Jean-Francois Trape ran four years from January 2007 through December 2010. Beginning in July 2008, people in Dielmo village, Senegal were offered longlasting insecticide (deltamethrin)-treated nets (LLINs).
The study noted a decrease in malaria rates until August 2010 when rates jumped back up to pre-bed net levels from before the distribution of the LLINs. Additionally, "37% of Anopheles gambiae mosquitoes were resistant to deltamethrin in 2010, and the prevalence of the Leu1014Phe kdr resistance mutation increased from 8% in 2007 to 48% in 2010."
The BBC reports:
"These findings are a great concern since they support the idea that insecticide resistance might not permit a substantial decrease in malaria morbidity in many parts of Africa," they write.It is valuable to note that the study was very small and it seems to indicate that the benefits outweigh the drawbacks. More research will ensue that will provide a better understanding into what may be happening. What this does illustrate is that there are unintended consequences that should be recognized when introducing an intervention.