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Last update: May 2013

The challenge

Malaria poses a tremendous public health problem. The World Health Organization (WHO) estimated that in 2010, there were 219 million cases of malaria (with an uncertainty range of 154 million to 289 million) leading to approximately 660,000 deaths (with an uncertainty range of 610 000 to 971 000), mostly among African children. Between 2000 and 2010 malaria mortality rates fell by more than 25% globally. Most deaths occur among children living in Africa where a child dies every minute from malaria. Although these reductions constitute major achievements in the global fight against malaria, these rates of decline are lower than global targets for 2010.


WHO country-level burden estimates available for 2010 show that an estimated 80% of malaria deaths occur in just 14 countries and about 80% of cases occur in 17 countries. Together, the Democratic Republic of the Congo and Nigeria account for over 40% of the estimated total of malaria deaths globally.

Plasmodium falciparum malaria endemicity

The highest levels of P. falciparum - the deadliest malaria parasite are found in Africa. It has been estimated that 342 million people remained exposed to this very high transmission risk in 2010.

 

Plasmodium falciparum malaria endemicity, 2010
P. falciparum transmission dominates across sub-Saharan African populations



Note: Map presents estimates of the annual mean Plasmodium falciparum parasite rate in children aged 2-10 (PfPR2-10) for 2010 within the spatial limits of stable P. falciparum malaria transmission. Areas in dark grey are very low/unstable transmission and those in light grey are at no risk.
Source: Malaria Atlas Project, Gething, PW. et al., A New World Malaria Map: Plasmodium falciparum endemicity in 2010, Malaria Journal, 2011, 10:378. 
 

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 to 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 through malaria vector control

The two most powerful and most broadly applied interventions for malaria vector control prevention are insecticide-treated mosquito nets (ITNs) and indoor residual spraying (IRS). However, malaria vector control with ITNs, IRS or other interventions is only effective with sustained high coverage.

 

Insecticide-treated mosquito nets (ITNs)/long-lasting insecticide- treated nets (LLINs)

Sleeping under 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 per cent 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 ITN 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 insecticide-treated nets (LLINs). These are nets 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 have been treated with a long-lasting insecticide.

 

Indoor residual spraying 

Indoor residual spraying (IRS) with WHO-approved chemicals (including DDT) is an effective malaria prevention method in settings where it is epidemiologically and logistically appropriate. IRS involves applying a long-lasting insecticide to the inside of houses and other structures to kill mosquitoes resting on interior walls. In most settings where IRS has been or is being deployed, ITNs or LLINs are already in use. Evidence has shown that the combination of IRS and LLINs is more effective than either intervention alone.


The main source of data on IRS 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 also been developed for household surveys.

 

Case management

Diagnosis

In 2010 WHO recommended universal use of diagnostic testing to confirm malaria infection, followed by appropriate treatment based on the results. According to the new guidelines, treatment solely on the basis of clinical suspicion should only be considered when a parasitological diagnosis is not accessible. Diagnosis is increasingly important, not only to have certainty about malaria cases but also to avoid unnecessary consumption of effective antimalarial drugs, such as artemisinin combination therapies (ACTs), which increases the risk of malaria parasite resistance.


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. However, 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 or rapid diagnostic tests (RDTs) is still scarce although it has been rapidly escalating in most countries during the past two years.

According to WHO guidelines, uncomplicated P. falciparum malaria (the most lethal and pervasive malaria parasite in sub-Saharan Africa) should be treated with an ACT. Over the last decade, most malaria-endemic countries shifted their national treatment policies to ACTs.


In settings with limited health facility access, diagnosis and treatment should be provided through a programme of community case management of malaria.

 

Malaria during pregnancy

Together with the regular use of insecticide-treated mosquito nets, intermittent preventive treatment during pregnancy (IPTp) is vital in the prevention of malaria among pregnant women in endemic areas.


Intermittent preventive treatment during pregnancy (IPTp)


IPTp refers to the administration of a full course of an effective antimalarial treatment at specified time points during pregnancy with the objective of reducing the malaria burden in pregnant women.


All pregnant women at risk of P. falciparum infection in countries in sub-Saharan Africa with stable malaria transmission should receive IPTp. The treatment consists of at least two doses of sulfadoxine-pyrimethamine (SP), which is considered a safe and appropriate drug for IPTp in malaria-endemic settings. The doses of SP should be taken under direct observation at the time of 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.

Antimalarial drug resistance

Antimalarial drug resistance is a major public health problem. The resistance of malaria parasites to conventional antimalarial monotherapies, such as chloroquine, SP and amodiaquine, has become widespread. ACTs are effective and recommended treatments for uncomplicated P. falciparum malaria and the first-line treatment in most sub-Saharan African countries.

References

Gething, P. et al., A New World Malaria Map: Plasmodium falciparum endemicity in 2010, Malaria Journal, 2011, 10:378.


Roll Back Malaria Partnership, A Decade of Partnership and Results, Progress & Impact Series, Report number 7, Geneva, September 2011.

 

WHO, World Malaria Report 2012, WHO, Geneva, 2012.   

 

WHO, UNICEF and PATH, Malaria Funding & Resource Utilization: The first decade of Roll Back Malaria, Progress & Impact Series, Report number 1, Geneva, March 2010.


UNICEF (on behalf of the RBM Partnership Secretariat) and PATH, World Malaria Day 2010: Africa update, Progress & Impact Series, Report number 2, 2010.


UNICEF, Malaria & Children: Progress in intervention coverage, UNICEF, New York, 2007.


UNICEF, Malaria & Children: Progress in intervention coverage, Summary update 2009, UNICEF, New York, 2009.