Malaria is transmitted to humans by Anopheles mosquitoes. Within the Anopheles genus (“genus” being a group of organisms with common characteristics), there are approximately 430 species. Of those species, according to the CDC, only about 30 to 40 species transmit malaria. These mosquitoes tend to feed at night, and indoors; knowledge that gave rise to popular malaria prevention methods such as insecticide-treated bed nets (ITNs).
A recent discovery from researchers at the London School of Hygiene and Tropical Medicine (LSHTM) and the Kenya Medical Research Institute Center for Global Health Research suggests the existence of a new malaria-carrying mosquito, a mosquito with different feeding patterns, which threatens those relying on current malaria prevention techniques.
In the September volume of Emerging Infectious Diseases, researchers pointed out that malaria prevention and control today relies on information about mosquito habits that might be outdated, so they endeavored to trap mosquitoes in Kenya for evaluation.
Between May and August of 2010, these researchers captured 422 mosquitoes for analysis. After DNA sequencing, 216 mosquitoes could not be matched to known Anopheles species. Further research showed that these new mosquitoes were frequently found outdoors between 6:30pm and 6:30am, meaning that people relying on ITNs were not protected.
Five of the new species tested positive for the malaria parasite Plasmodium falciparum, the parasite that causes the most severe form of malaria.
The study is significant for several reasons. First, the newly discovered mosquitoes are active outdoors and at earlier times of the day, which could affect malaria control and reduction efforts. Second, it emphasizes how necessary mosquito population surveillance is. As Jo Lines, from the LSHTM and formerly of the WHO Global Malaria Programme, says, “[T]here is no substitute for careful monitoring of mosquito populations. In order to be effective, such monitoring must be carried out by specialist experts who have the skills to recognize and investigate unexpected entomological observations.”