The challenge

An estimated 3 billion people, almost half the world’s population, live in areas where malaria transmission occurs. Malaria is endemic in 107 countries and territories in tropical and subtropical regions, with sub-Saharan Africa hardest hit. Between 350 million and 500 million cases of clinical malaria occur each year, leading to an estimated 1 million deaths. Over 80 per cent of these deaths—or at least 800,000 a year—occur among African children under age five.

Children who survive malaria do not escape unharmed. Repeated episodes of fever and anemia 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 anemia in the mother and the presence of parasites in the placenta, which contributes 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. Importantly, malaria disproportionately affects the poorest people in these countries and therefore also contributes to their further impoverishment.

The disease

Malaria 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 upon the species of infected Anopheles mosquito, 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. Early diagnosis and treatment saves lives and prevents the development of complications: A 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. If children, in particular, are not treated within a day, the disease can lead to death. In most cases, severe anaemia is the attributable cause of death.

Prevention and treatment

Insecticide-treated mosquito nets

Insecticide-treated nets are one of the most effective ways to prevent malaria transmission, and studies have shown that regular use can reduce overall under-five mortality rates by about 20 per cent in malaria-endemic areas. Malaria-infected mosquitoes bite at night, and these nets provide a sleeping individual 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. Long-lasting insecticidal nets, a recent technological innovation, 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 three years under field conditions. WHO now recommends that national malaria control programmes and their partners purchase only long-lasting nets.

 

Prompt and effective treatment

Prompt and effective treatment of malaria within 24 hours of the onset of symptoms is necessary to prevent life-threatening complications. There are several challenges to providing prompt and effective treatment for malaria in Africa. First, the majority of malaria cases are not seen within the formal health sector. Second, the resistance of P. falciparum parasites to conventional antimalarial monotherapies, such as chloroquine, sulfadoxine-pyrimethamine and amodiaquine, has become widespread, resulting in new treatment recommendations. The World Health Organization now recommends treating malaria using artemisinin-based combination therapies, which are 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.            

 

Prevention and control during pregnancy

Together with regular insecticide-treated net use, intermittent preventive treatment during pregnancy is key in preventing 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 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.    

 

Indoor residual spraying

Indoor residual spraying 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. However, given the recent interest in scaling up the use of this malaria control strategy, standardized indicators and household data collection methods are being developed for future household surveys.