Malaria: The science of a first strike attack
Mosquito nets are the best-known tool for preventing malaria. But they are only one example of what public health officials call “vector control.”
To the rest of us, vector control means controlling the mosquito that carries malaria — either by setting up a barrier, or better, not letting it grow to adulthood in the first place. “It’s not very politically correct to say this,” noted epidemiologist Pedro Alonso in an interview in Mozambique last year, “but the greatest malaria fighter in Europe was Mussolini, because he drained Rome’s swamps.”
In a 2006 report from its Malaria Study Group, the World Health Organization identified five main vector control goals, most of which are now implemented to varying degrees in most malarial regions. Nets treated with insect repellent led the list, but the world body also studied the effectiveness of spraying for adult insects, spraying separately for larvae, and selective draining of small areas where water collects — yards and dips in roads, for example.
In several South American countries, notably Amazonian Brazil and Colombia, small programs of “social participation” are also in place, designed to encourage residents of malaria-endemic zones to prevent stagnant water from collecting near homes, by storing empty containers upside down and capping open wells.
Vector control strategies do compete in a broad sense with vaccine strategies for funding. But in practice both strategies end up in use.
Even in Manhica, Mozambique — home to the Manhica Health Research Center — researchers found malaria rates for people living on the local district’s southern end were much better than average, due to vector control.
Further study showed that residents of that area, the site of a successful sugar plantation, were better off financially, so were likely to live in homes with doors and windows screened against insects. They also had better plumbing and in some cases air-conditioning. In the rest of the district, residents were poorer and more likely to live in open structures or huts, and bad plumbing meant that more water was stored in open jugs.
In poorer areas, nets were the only defense. In wealthier homes, nets were still in use, but served as more of a secondary defense. They only had to stop the few insects that made it past a well-screened, or even closed, window.
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