Impregnated bed nets for malaria control: biological success and social responsibility

Malaria is a serious public health problem in numerous countries of the world. In Africa alone, it is estimated that more than a million children less than five years of age die each year from this disease. The problem has become more critical with the development of Plasmodium falciparum resistance to chloroquine, the high cost of replacement antimalarials, and vector resistance to the cheaper insecticides such as DDT. Emphasis now is on sustainable control programs that can be implemented by communities with assistance from primary health care providers. This has led to a re-examination of impregnated bed nets (IBNs) that serve as a physical barrier to break human-vector contact. Over the last decade, bed nets impregnated with cheap and long-lasting pyrethroids used in Africa and Asia have shown their utility in reducing human-vector contact, inoculation of humans with sporozoites, clinical episodes of fever, and high levels of parasitemia. One study in The Gambia demonstrated that mortality in young children was significantly reduced, and the results of that study have led to the initiation of large-scale mortality studies in different epidemiologic areas in Africa. This paper reviews current bed net materials, recommended insecticides, an impregnation technique, costs, and the importance of community participation. As a malaria control option IBNs appear to be very promising, but further entomologic and epidemiologic assessments, including mortality studies, are needed. Future use of IBNs should be considered as part of a larger program that includes other vector control measures, proper case management, appropriate use of antimalarials for prevention in specific target groups, surveillance, and program monitoring with attention to changing epidemiologic situations and developing technology.