The challenge

Malaria poses a tremendous public health problem. The World Health Organization (WHO) estimated that in 2008 there were 250 million malaria episodes, leading to approximately 850,000 malaria deaths. While malaria is endemic within most tropical and subtropical regions of the world, 90 per cent of all malaria deaths currently occur in sub-Saharan Africa, and most of these deaths are among children under five years of age. Approximately 1 in every 6 child deaths (16%) in Africa is due to malaria.

Malaria* global endemicity
Intensity of the Plasmodium falciparum parasite prevalence rates in children aged 2–10

* Refers to Plasmodium falciparum which is one of the four malaria parasites that affect humans. It is also the most common in Africa and the most deadly.
Source: Malaria Atlas Project.
Map note: The light colour shows low intensity and the darker colour shows the highest intensity of malaria transmission (grey = no malaria transmission). The dotted line represents approximately the Line of Control in Jammu and Kashmir agreed upon by India and Pakistan. The final status of Jammu and Kashmir has not yet been agreed upon by the parties.

Children who survive malaria do not escape unharmed. Repeated episodes of fever and anaemia take a toll on their mental and physical development, impairing their education and their growth into productive adults. Pregnant women and their unborn children are also particularly vulnerable to malaria even in areas of stable transmission since malaria infection may lead to malaria-related anaemia in the mother and the presence of parasites in the placenta, which contribute to low birthweight – a leading cause of impaired development and infant mortality. Malaria has a devastating effect on adults as well, because repeated infections drain their capacities.

The cumulative effects of the disease are equally devastating to societies. Studies have shown that malaria contributes to reduced economic growth in affected African countries. It is significant that malaria disproportionately affects the poorest people in these countries and therefore also contributes to their further impoverishment.

The disease

Malaria is a life-threatening vector-borne disease transmitted to people exclusively through the bites of Anopheles mosquitoes, also called "malaria vectors". Malaria is caused by the Plasmodium parasites carried by the mosquitoes. It is a disease of warm, humid climates where pools of water constitute perfect breeding grounds for the Anopheles mosquito. With the bite of the mosquito, malaria parasites are transmitted from infected to healthy people. Once in the bloodstream, the mature parasites reach the liver where they multiply. The rapid multiplication of the parasite causes the destruction of red blood cells and the infection of new cells throughout the body. Depending on various factors such as the parasite, the vector, the human host, and the environment, the infected person will become ill with malaria after about a week to several months, but mostly within 7–21 days.

Symptoms

The most important sign of malaria is fever. The symptoms in children and adults infected with malaria might also include shivering, severe pain in the joints, headaches, vomiting, generalized convulsions and coma, but also coughing and diarrhoea. If children, in particular, are not treated within 24 hours of fever onset, malaria can progress to severe illness often leading to death. Early diagnosis and treatment saves lives and prevents the development of complications. For instance,  very high body temperature, drowsiness, convulsions and coma are indicative of cerebral malaria. Jaundice and reduced urine output are signs of liver and/or kidney failure. In most cases, severe anaemia is the attributable cause of death.

Prevention and treatment

Today, malaria can be prevented, diagnosed and treated with a combination of increasingly available tools. Controlling malaria is based on both preventing the infection and on prompt effective treatment of the infection and treatment when it does occur. Among the primary tools used for prevention are insecticide-treated mosquito nets, indoor residual spraying and intermittent preventive treatment during pregnancy.

Insecticide-treated mosquito nets (ITNs)

Sleeping under insecticide-treated mosquito nets (ITNs) is one of the most effective ways to prevent malaria transmission, and studies have shown that regular use can reduce all-cause child mortality by around 20% in malaria-endemic areas. Malaria-infected mosquitoes bite at night, and ITNs provide a sleeping individual with a physical barrier against the bite of an infected mosquito. In addition, a net treated with insecticide provides much greater protection by repelling or killing mosquitoes that rest on the net – an additional and important protective effect that extends beyond the individual to the community. The protective effect to non-users in the community is difficult to quantify but seems to extend over several hundred metres.   

A mosquito net is classified as an insecticide-treated net if it has been treated with insecticide within the previous 12 months. WHO now recommends that national malaria control programmes and their partners purchase only long-lasting insecticidal nets (LLINs), which are nets that have been permanently treated with insecticide that lasts for the useful life of a mosquito net  (defined as at least 20 washes and at least 3 years under field conditions). Nowadays, most ITNs are LLINs.

Indoor residual spraying (IRS)

IRS is an effective malaria prevention method in settings where it is epidemiologically and logistically appropriate. Indoor residual spraying involves applying a long-lasting insecticide to the inside of houses and other structures to kill mosquitoes resting on interior walls. The main source of data on indoor residual spraying coverage is Ministry of Health programme records and documents. Given the recent interest in scaling up the use of this malaria control strategy, standardized indicators and household data collection methods have been developed for future household surveys.

Intermittent preventive treatment during pregnancy (IPTp)

Together with the regular use of insecticide-treated mosquito nets, intermittent preventive treatment during pregnancy is vital in the prevention of malaria among pregnant women in endemic areas. Intermittent preventive treatment is not recommended in areas of low or unstable malaria transmission. The treatment consists of at least two doses of an effective antimalarial drug during antenatal care visits during the second and third trimesters of pregnancy. This intervention is highly effective in reducing the proportion of women with anaemia and placental malaria infection at delivery. Currently, sulfadoxine-pyrimethamine is considered a safe and appropriate drug for intermittent preventive treatment for pregnant women in malaria endemic settings.

Prompt and effective treatment

Prompt and effective treatment of malaria within 24 hours of fever  onset  with an effective antimalarial agent is necessary to prevent life-threatening complications. There are several challenges to providing prompt and effective treatment for malaria, particularly in Africa. First, the majority of malaria cases are not seen within the formal health sector. Second, rapid malaria diagnosis (with microscopy of rapid diagnostics tests RDTs) is scarce but increasingly important, in order to have certainty about malaria cases. Finally, the resistance of malaria parasites to conventional antimalarial monotherapies, such as chloroquine, sulfadoxine-pyrimethamine and amodiaquine, has become widespread, posing a threat to intervention effectiveness.

WHO now recommends treating malaria using artemisinin-based combination therapies (ACT), which is more effective but more costly than other therapies. ACT is based on combinations of artemisinin, extracted from the plant Artemisia annua, with other effective antimalarial medicines. When combined with other medicines, artemisinin derivatives are highly potent, fast acting and very well tolerated.