The Outdoor Mosquito: A new enemy in view for the malaria fighters
By Fiorenzo Conte
Malaria control interventions too often focus exclusively on protecting man from being bitten by mosquitoes as opposed to controlling the mosquitoes population. Distribution of insecticide treated nets and early detection and treatment in particular for pregnant women constitutes the main paradigm embraced by the international community. The malaria campaigns rolled out in Benin, where I am currently living and working, are just another example of interventions whose goal is to achieve a high geographical coverage of bed nets.
A new finding by scientists in Burkina Faso and published in Science shows however why these types of interventions could fall short of their objectives. A team of researchers has discovered a new type of mosquito which is particularly susceptible to the Plasmodium parasite. This mosquito presents an uncommon characteristic: they live and bite outside.
This discovery teaches two lessons about the design of anti-malaria intervention. First: as a malaria researcher at the Liverpool University explains to BBC “to control malaria in an area you need to know what mosquitoes are passing on the disease in that district, and to do that you need sampling methods that record all significant disease vectors. You need to determine what they feed on, when and where, and whether they are infectious”
Second lesson: if you find out that mosquitoes that spread the parasite do not rest indoors after they bite you should probably complement bed nets distribution with other interventions i.e. environmental management such as larviciding and breeding pool removal. For example, the key for the success of the campaign led by Fred Soper that eradicated the Anapholes Gambiae in North East Brazil was the spraying of Paris Green (an arsenic based mixture) and diesel oil on water pools where larvae bred. Unfortunately the lessons of past successes such as this in Brazil seem to be forgotten by the contemporary health community. Result? Interventions ignore that the fight against malaria is also about fighting the vector and therefore the environment in which it breeds. These new findings remind us that the strategies to tackle malaria needs to be multi-pronged if they are to be successful to fight this disease.