Veiled behind a bednet is a simple truth: no vector control technology has been implemented in Africa. Billions of dollars are being spent on malaria control in Africa, and numerous entomologists are enlisted to advise about deployment of two mainstays of “vector control” efforts, bednets and IRS. In spite of this, if one were designing a vector control method and these were proposed, would they even rank among the top ten list of effective possibilities?
On the contrary, bednets primarily prevent human/mosquito contact. The effect of local mosquito population suppression when they are intensively used was not their intent nor planned and is merely a secondary effect.
Similarly, IRS targets indoor-resting females. Again, the purpose is not to suppress mosquito populations but to kill those that are likely to have fed on human blood and become infective. IRS is an anti-parasite measure.
Both of these tools are poor excuses for mosquito population suppression methods. They can be considered vector control as rightly as finger pricks can be considered a method of reducing parasite load.
If one wanted to suppress vector populations, what possibilities are available for Africa? Therein lies the rub. There is simply no intervention in use – and possibly in existence - that is appropriate and designed to control mosquitoes effectively, but pretending that IRS and LLIN are vector control methods distracts researchers from developing the real thing.
This fact has implications for investment in research to develop new methods. Developing new insecticides that will extend the value of LLINs and IRS should not be thought of as vector control efforts since the vehicles by which they are applied are not methods chosen to suppress vector populations. Only if such chemicals will be applied in different ways that are designed for vector control will they bring something new to the table. Exploring methods, including insecticides, for area-wide larval or adult control would in fact be a true vector control implementation. Similarly, the promising - but not yet delivering – method of genetic control might eventually offer a true malaria vector control method.
Malaria is a three-legged stool resting on humans, mosquitoes and parasites. Remove any one and the stool will not stand. At present, only one of the two potential vulnerable legs is being attacked. Isn’t it time to quit believing that we are attacking the mosquito leg with LLIN and IRS and to think more creatively of new vector control methods? That recognition would elevate the perception that there is a huge unexploited vulnerability.
In spite of their weak anti-vector effects, LLIN and IRS are effective malaria interventions. What would be possible if a true vector control program were developed and implemented?