Intermittent Preventive Treatment for Malaria in Sub-Saharan African: A Halfway Technology or a Critical Intervention?

Abstract

In what was a highly influential but is now, sadly, largely forgotten essay, the eminent medical scholar Lewis Thomas distinguished halfway technologies from high technologies. He noted that while halfway technologies are simultaneously sophisticated and primitive, they are carried out after the fact, and they are “the kind of thing that one must continue to do until there is a genuine understanding of the mechanisms involved in disease.” 1, 2 The notion of halfway technologies seems to apply fully to intermittent preventive therapy (as well as bednets) for malaria. On the other hand, Thomas characterized high technologies as “the most decisive technology of modern medicine,” which in the context of malaria aims at the holy grail of a highly effective vaccine. Yet because we lack precise knowledge of mechanisms of anti-malarial immunity in humans, the silver bullet of the long-promised malaria vaccine remains elusive. This lesson applies fully today to the global context of malaria. We know that malaria causes poverty; that poverty causes malaria. It is generally agreed that until a highly efficacious and deployable vaccine to eradicate malaria becomes available, all means available must be used to ameliorate the effects of malaria on human populations. In the short run we must temporize, always looking towards more definitive interventions that include global malaria eradication. The prospect of any highly effective, inexpensive, and easily administered intervention to reduce the public health burden of malaria is always attractive. 3 Recent years have seen the advent of intermittent preventive treatment (IPT) (also called intermittent presumptive therapy) in malaria as one approach. IPT is distinguished from frank malaria chemoprophylaxis by the periodic, scheduled use of inexpensive anti-malarial drugs to reduce the burden of malaria, in the context of other programmatic measures such as prenatal care and infant immunization. In contrast, systematic chemoprophylaxis is difficult to deploy effectively and comprehensively in malaria-endemic regions, so that integration of an intermediate method of chemoprophylaxis into ongoing programmatic measures is practical, if not ideal. Unfortunately, parasite biology often seems to get in the way of what would seem to be important and sensible public health measures. The use of antimalarials to prevent malaria on a population basis—notably chloroquine and pyrimethamine— has been long recommended but logistically difficult to implement. Significant concerns are consistently raised about such measures selecting for drug resistance. One might have predicted–because of the rapid spread of resistance over the past decade–that IPT in pregnancy using the current standard sulfadoxine-pyrimethamine (SP) might be less effective throughout sub-Saharan Africa than when it was first implemented.