Burden of Malaria in Sub-Saharan Africa
Burden of Malaria in Sub-Saharan Africa
A girl awakens in her bed covered with an anti-malarial mosquito net in Dundube Kadambo, Malawi. The widespread use of bednets is one of several effective measures to cut down on the transmission of malaria. © 2009 Paul Jeffrey, Courtesy of Photoshare
All over the sub-Saharan region of Africa, the burden of malaria has been decreasing in the past 3-5 years with expanding coverage of malaria prevention and treatment in many countries. These occurrences are spread across the region, occurring in Ethiopia, Kenya, The Gambia, Rwanda, and Zambia that each possess varying transmission intensities. In Ethiopia, documents of declines in malaria morbidity of 70% have been reported amongst adults and children less than 5 years old. In Eritrea, substantial reductions in routinely reported clinical malaria cases were reported following a scale-up of control interventions, including insecticide-treated bednets, artemisinin combination therapies, and community health-worker training. In Kenya, pediatric malaria admissions declined by as much as 75% between 2003 and 2007.
A woman receives basic medical assistance for malaria in Abeche, Chad. She traveled two days from her remote village in the flooded southeast region of Chad to receive care. © 2008 Micah Albert, Courtesy of Photoshare
In some instances, these various interventions - ITNs, ACTs, indoor residual spraying, larval control - have not coincided with reductions in the prevalence and case-fatality rates of malaria. In some reports, the decline began before the specific intervention was implemented, or the decline was already underway at the beginning of the study period, suggesting that confounding factors, other than the interventions to which the declines are attributed, may have contributed to the decline. For instance, in the coastal area of Kenya, although ITN use has increased simultaneously with the decline in pediatric admissions for malaria, the prevalence of malaria infection declined from 35% to 10% before ITN coverage reached 25%, and before the introduction of ACTs. Similarly, in The Gambia and Zanibar, the decline in malaria began before ITNs were introduced.
A young boy in Kisumu, Kenya, sleeps beneath a treated mosquito net provided to rural residents as part of a malaria eradication campaign by the Centers for Disease Control (CDC). The CDC has worked in this malaria- prone region of Kenya since the late 1970s to help reduce the mortality rates from malaria. © 2009 David Snyder, Courtesy of Photoshare
Based on such data, researchers have begun to consider other factors that may contribute to the control and prevention of malaria. Studies in North America and Europe have shown, for instance, that malaria declines as social conditions, such as improvements in housing situations, and education improve; however, these probably cannot account for the drastic declines in malaria seen in sub-Saharan Africa recently. Another factor worth considering is climate. Climate can strongly affect malaria transmission, but no patterns have emerged in sub-Saharan Africa that could explain the exceptional reductions in malaria in some countries. Experts also pose biological possibilities such as changes in the parasite or its mosquito vector or the fact that the transmissibility of malaria might not be as high as has been previously thought.
A woman and child with their new mosquito net in Dangbo, Benin, which experiences large-scale flooding every rainy season. Long-lasting insecticide treated nets provided by the President's Malaria Initiative were provided to every family in the area. © 2009 Nate Miller, Courtesy of Photoshare
Additionally, researchers are wary of the limitations in using published scientific literature in assessing the progress made of ongoing malaria in developing countries. Many studies can be biased towards one of two extremes - presenting data that reflect well on the outcome of control interventions to justify investments or presenting data to imply that the malaria burden is worsening to encourage further investment in malaria control. Situations in which the prevalence of malaria has remained the same and interventions have not yielded significant results are most likely not mentioned or reported on. Regardless, the overall picture depicted by these studies is encouraging. Most reports show a substantial, recent decline in the burden of malaria, and in countries where no recent reports have been given, there has probably been little change in the malaria burden.