Personal ViewMalaria: current status of control, diagnosis, treatment, and a proposed agenda for research and development
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Incidence, burden, and economic consequences
More than a third of the world's population (about 2 billion people) live in malaria-endemic areas, and 1 billion people are estimated to carry parasites at any one time. In Africa alone, there are an estimated 200–450 million cases of fever in children infected with malaria parasites each year.3 Estimates for annual malaria mortality range from 0·5 to 3·0 million people.4 These are imprecise estimates because there has been little investment in proper documentation of the epidemiology and
Prevention of infection
After World War II, widespread use of DDT coupled with the covering and draining of breeding grounds resulted in a substantial reduction in mosquito populations and, together with effective treatment, eradicated malaria in southern Europe, Russia, and parts of Asia. Although substantial successes were achieved in subtropical regions, control of malaria in the tropics proved far more challenging. The effectiveness of the control effort was undermined through a combination of difficult access to
Diagnosis
Access to medical care is limited in many malaria-endemic areas. Where medical services exist, they commonly lack facilities for laboratory diagnosis. As a result, malaria treatment is mostly given on the basis of clinical or self diagnosis. However, clinical diagnosis is very inaccurate, even in areas where malaria is a common cause of fever, because signs and symptoms of uncomplicated malaria are nonspecific and overlap with those of other febrile infectious diseases,46, 47 and because the
Treatment access
Prompt and effective treatment is probably the most cost-effective element of malaria control.65 The bulk of antimalarial therapy worldwide is oral drugs for uncomplicated falciparum malaria. Oral treatment prevents progression to severe disease and complications, and, if the drugs are efficacious and applied effectively, they reduce overall malaria morbidity and mortality.66, 67 However, most people living in endemic areas have little or no access to diagnosis and treatment; moreover,
Plasmodium vivax malaria
P vivax predominates in South America and parts of Asia. Resistance of this parasite to chloroquine is geographically still limited,96 though likely to increase. Although it causes recurring and debilitating infections, P vivax rarely kills. In contrast to falciparum malaria, treatment must clear not only blood-stage parasites but also ‘dormant’ parasites (hypnozoites) in the liver, which cause relapse. Therefore, chloroquine should be combined with primaquine. A 2-week treatment course is
How can research help?
The quality of care for people with malaria today is simply unacceptable, and the global response to this crisis has been inadequate. The reasons for the failure are a complex mixture of financial, political, logistic, and operational factors: the main target populations live in the poorest countries, and even within these countries the rural poor are often under-represented in the corridors of power. And so malaria escapes the normal laws of supply and demand, while ineffective treatments are
Conclusions
Combating malaria is possible, but increased funding is needed to mobilise and optimise existing tools (table 2). In the longer term, support will be needed to channel the results from fundamental research into truly new control tools (eg, new drugs, diagnosis, insecticides, and vaccines). A small part of funds presently devoted to control measures needs to be committed to continuous assessment of their true effect. Efficacious antimalarial-combination treatments are available now that will
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