Malaria - the disease
The Malaria and Health website is dedicated to providing the health care professional with up-to-date information on malaria and the options available for controlling the disease. The following sections contain information on the scale of the problem of malaria, signs and symptoms, details of malaria meetings and various downloadable malaria resources. In addition, antimalarial drugs are explored, including published data on the latest ACT drugs and information on standby emergency treatment.
Source: RBM/WHO 05
Malaria is the world’s most important parasitic infection in man. As such, it is one of the most serious challenges to modern healthcare. Each year, there are at least 350-500 million clinical cases of malaria worldwide and at least 1 million people die in Africa alone.1 Yet despite these estimates, we really do not know the true extent of the disease. The figures for reported cases vary widely and suggest that only a tiny fraction of those in need of treatment ever get access to it. The latest studies estimate that there were 515 (range 300-660) million episodes of clinical P.falciparum malaria in 20022 – up to 50% higher than those reported by the World Health Organization (WHO) and 200% higher for areas outside Africa.
The vast majority of malaria patients live in endemic countries of the tropics. However, over the past few decades, the number of tourists and business people visiting these areas has increased sharply, and more than 125 million travellers are now at risk for acquiring malaria.3 Risk of acquiring malaria also varies according to:
- geographic location
- time
- immune status of the person
- degree of their exposure to the parasite.
Frequent or chronic exposure to malaria infection over prolonged periods produces some degree of immunity. However, acquired immunity is partial and wanes when exposure to the parasite has ceased, so when previously immune people move outside a malarial area for some years, they are at higher risk of severe malaria when they return.
In highly endemic areas, people who have been repeatedly infected with malaria acquire a level of immunity to malaria which suppresses most clinical symptoms. However, these people may still carry gametocytes in their blood that will infect the mosquitoes biting them. Therefore, in areas of high endemicity, partially immune adults represent a large reservoir of infection, which threatens non-immune individuals such as infants and travellers.
In areas where malaria is endemic, prevention relies on control of the mosquito vector by:
- spraying and drainage of habitats
- insecticide treated bed nets (ITNs)
- indoor residual insecticide spraying (IRS)
- intermittent preventive treatment (IPT)
- acute drug treatment in low transmission areas.
Non-immune travellers are at a substantial risk of acquiring falciparum malaria and if travelling to areas where malaria is present, are advised to take appropriate measures to avoid mosquito bites; to use an antimalarial prophylactic drug when appropriate and to immediately seek diagnosis and treatment if a fever develops one week or more after entering an area where there is a malaria risk, and up to 3 months after departure. Pregnant women and children should avoid traveling in regions where malaria is endemic.
According to the World Health Organization (2006), resistance has arisen to all classes of antimalarials except, as yet, to the artemisinin derivatives, such as Coartem®. This has increased the global malaria burden and is a major threat to malaria control. Widespread and indiscriminate use of antimalarials places a strong selective pressure on malaria parasites to develop high levels of resistance. Resistance can be prevented, or its onset slowed by combining antimalarials with different modes of action.
Novartis, a leading life-sciences company, is now meeting the challenge of malaria with the combination drug therapy - Coartem®/Riamet®.
In this Website, we focus on malaria caused by P. falciparum (falciparum malaria) unless indicated otherwise.
