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 June 2006, Vol. 12, No. 2 Public Health
Malaria, a life-threatening parasitic disease, is endemic in about 90 countries of the world, half of which are in Africa. The disease kills more than one million people every year, most of them children. Malaria, like HIV and tuberculosis, is a major public health challenge in the poorest countries of the world. Despite this fact, little systematic attention has been directed to researching the demographic impact of malaria in Africa. Recently, Ayaga A. Bawah, a Population Council Berelson Postdoctoral Fellow, and his colleague Fred N. Binka, executive director of the INDEPTH-Network in Ghana, investigated how many years of life could be saved if malaria were eliminated from a hyperendemic area of northern Ghana. What is malaria? Using classic demographic methodology, Bawah and Binka analyzed data that had been collected in the Navrongo Demographic Surveillance System (NDSS). Researchers working on this database record information on nearly all births, deaths, migrations, marriages, and pregnancies in the Kassena-Nankana District of northern Ghana. They conduct “verbal autopsies” on all recorded deaths to ascertain the probable cause of death. Verbal autopsies involve interviews with relatives and caregivers who were closely involved with the deceased during and up to the time of death. Verbal autopsies are used in settings where the majority of deaths occur outside of health facilities and where official records of the cause of death do not exist. Bawah and Binka used 1995 data, which at the time of their analysis represented the only complete data set on causes of death. They looked only at the rural population, because data on the urban population were not integrated into the NDSS until the end of 1995. The data set comprised a total population of 126,000 with about 2,000 deaths. Their verbal autopsies revealed that nearly a third of all childhood deaths and about a fifth of adult deaths are attributable to malaria in this setting. The researchers analyzed the data using both single- and multiple-decrement life tables, showing the probability of surviving to each age with and without malaria. This analytic technique allowed them to determine the extent to which mortality could be reduced and life expectancy increased if malaria were eliminated from the population. They also established which age groups would benefit the most from a decline in mortality from malaria. In the first stage of the analysis, they separated out malaria from all other causes of death, including deaths for which the cause could not be established from the verbal autopsy accounts. They then estimated the impact of deaths from malaria on overall mortality. In the second stage of the analysis, they assumed that the deaths from unknown causes actually were caused by ailments similar to those for which the cause is known. Thus, they proportionately distributed the unknown cases among the known causes and reran the analysis. The data showed that life expectancy at birth in 1995 was 48.8 years. The first stage of the analysis—in which unknown causes of death were assumed to be unrelated to known causes—showed that if malaria were eliminated, life expectancy at birth would increase to 54.9 years. “As of 1995, if malaria had been eliminated, life expectancy could have increased by as much as 6 years,” explains Bawah. “That is a huge increase from eliminating a single cause of death. Since mortality from malaria is greatest in childhood, the biggest contribution to the potential increase in life expectancy at birth is likely to come from eliminating deaths among infants and children younger than five years.” Moreover, the second stage of the analysis—in which the deaths from unknown causes were proportionately distributed among known causes of death—showed that life expectancy at birth would increase to 58.2 years if malaria were eliminated, representing an estimated probable gain of 9.4 years. The researchers conclude, “Our analysis suggests that the malaria epidemic represents one of the major challenges facing Africa medically, socially, and economically. Our results attest to the need for a concerted effort to build scientific understanding of this preventable yet deadly disease.” Source See Also
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