Scientific American is known for making the latest scientific advances – from dark matter to disease management – accessible to a wide audience.Â An article in the November 2010 issue on malaria vaccine progress is generally a good example. The following passage though, may simplify the history of eradication a bit too much.
In the 1960s an enormous campaign wiped out the disease in many parts of the world and drove down its number in others. But that success ultimately bred its own end. As malaria became perceived as less of a threat, global health agencies became complacent; their chief tool, DDT, was found to be toxic to birds, and they largely abandoned their efforts. Malaria numbers roared back more fiercely than before.
Two specific issues from the foregoing do not paint the full picture. First, bird deaths did not stop malaria eradication, though the toxicity issue is true in its own context. The real end of DDT was bred by mosquitoes developing resistance to the pesticide, which was discerned even before the campaign reached its height. The Lancet in reviewing Randal Packard’s book, The Making of a Tropical Disease, a Short History of Malaria, explained that …
It (the eradication campaign)was far too monodimensional, relied too much on DDT spraying, and neglected the palpable problem that the delivery infrastructure was not in place in too many parts of the malarious world. The emergence of widespread mosquito resistance to DDT, and parasite resistance to the cheap mainstay of therapy, chloroquine, compounded the difficulties.
Secondly, at least for colleagues in the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), malaria research overall did not halt. Surely the funding levels were not as high as we see today, but persistent research provided us with new tools including insecticide treated bednets, artemisinin-based combination therapy, and nearly a dozen insecticides for indoor residual spraying, for which we are thankful.
True, these additional tools do not confer permanent immunity as a vaccine eventually should, but their implementation has driven down the number of malaria deaths in many countries, and when a vaccine comes along to strengthen the toolkit, we will be farther down the long road to elimination. The malaria lifecycle is complex, and health systems designed to deliver malaria interventions is equally complex (and challenging), which means we cannotÂ and should not expect a magic bullet in the near future.
As Randal Packard pointed out a key lesson from the first eradication campaign needs repetition, lest we again blame it all on the birds. Aside from developing insecticide resistance, there was clear indication that the health systems in the most highly endemic areas were not able to maintain continuous IRS application.
Health systems are stronger today, due in part to recognition by partners (international and internal) that malaria cannot be controlled, much less eliminated, without health system strengthening. It is these same health systems that will also be required to deliver the new malaria vaccines, so they better be strengthened before vaccines are rolled out.
Another short note of concern about the Scientific American article – in a box entitled “Plan B: Vaccine Alternatives” we are correctly shown that the effort to eliminate malaria has other tools that must be sustained. Unfortunately the text refers to malaria as a ‘virus’, though elsewhere in the article the stress on ‘parasite’ prevails.