Malaria research : an audit of international activity / J. Anderson, M. MacLean and C. Davies.

  • Anderson, J.
Date:
1996
Catalogue details

Licence: Public Domain Mark

Credit: Malaria research : an audit of international activity / J. Anderson, M. MacLean and C. Davies. Source: Wellcome Collection.

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    1.4 ECONOMIC SIGNIFICANCE OF MALARIA In 1987 the estimated annual direct and indi- rect cost of malaria in Africa was US$800 mil- lion, and this figure was expected to rise to more than US$1800 million by 1995. The worldwide cost associated with malaria is undoubtedly higher, however, possibly reach- ing US$2000 million in 1995 (assuming that Africa has 90 per cent of the worldwide malaria cases). For the control of the disease alone, the WHO Action Plan for Malaria Control, 1995-2000 (WHO, 1995c) has estimated that approxi- mately US$28 million per annum of external investment in malaria control will be needed in Africa. Outside Africa, malaria control programmes cost an estimated US$175—350 million a year. 1.5 THE DISEASE Excellent reviews of the disease and its history are provided by Bruce-Chwatt (1985), Oaks etal. (1991), and the WHO (1993). An out- line of certain biological and historical aspects of the disease is given here, but readers are referred to the above texts for further infor- mation. Malaria is a disease caused by four species of protozoan parasites of the genus Plasmodium: P. falciparum, P. vivax, P. ovale and P. malariae. Plasmodium falciparum is responsible for the most severe manifestations of the disease. The parasite matures and reproduces sexually in the mosquito Anopheles, and is transmitted through that vector to humans. Transmission occurs through the lemale mos- quito, which requires a blood meal for the development of her eggs. The parasite sporo- zoites, which enter the human blood with the saliva of the biting mosquito, invade the liver cells where they develop and multiply. Merozoites, released into the blood from the liver, invade the red blood cells and initiate the cycle of development and multiplication that brings about the clinical symptoms of the disease. Malaria is best thought of as a collective name for different diseases, since the epidemiology of malaria transmission and the severity of the disease vary greatly from region to region, vil- lage to village, and even from person to person within a village. Some of these differences will be due to the particular species of the parasite, the degree of compliance with a drug regimen, local patterns of drug resistance, and an indi- viduals immunity. 1.6 HISTORY OF RESEARCH AND OF MEASURES AIMED AT CONTROL AND TREATMENT OF THE DISEASE In the fifth century BC, Hippocrates discarded superstition as a cause for the fevers which afflicted ancient Greeks. He recognized the seasonality of the fevers, and described the early clinical manifestations and complications of malaria. However, it was not until the seventeenth century that a breakthrough occurred in the treatment of the malarial fevers. The bark of the Peruvian tree, Cinchona, was discovered as the first therapy for the disease. The active principle of the bark, quinine, was later isolated. The devastating effects of malaria during the First World War stimulated research for synthetic antimalarial drugs, which were first discovered in the 1920s (pamaquine) and 1930s (chloroquine). Also at this time, a major discovery in the con- trol of malaria, through the use of a natural insecticide, established the cornerstone of malaria control. Pyrethrum, an extract of the chrysanthemum, was mixed with kerosene and sprayed on the walls of houses. Several
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