Malaria prevention and control

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Malaria causes around 600,000 deaths each year, mainly in children in sub-Saharan Africa, and families, governments, and donors spend considerable amounts of money on diagnosis, treatment and prevention. To ensure this money is spent wisely, The Cochrane Collaboration prepare independent reviews of the evidence in prevention and treatment.

Malaria is transmitted from person to person by infected mosquitoes. Potential malaria control strategies include reducing the number of mosquitoes, reducing the number of mosquito bites, and reducing the number of people infected with the malaria parasite in the community. Some groups of people, such as young children and pregnant women, are at high risk of malaria complications and deaths where targeted prevention strategies may be of benefit.

Reducing mosquito numbers

Mosquito larval source management for controlling malaria
Mosquitos typically breed in standing water sites such as water containers, wells, puddles, ponds, and swamps. Larval source management aims to reduce malaria by targeting immature mosquitoes before they develop into flying adults, and includes interventions such as covering or removing water containers, draining water bodies, and adding larvicide to ponds and swamps. This review assesses the impact of these interventions on mosquito numbers, and malaria transmission.

Larvivorous fish for preventing malaria transmission
In the past, malaria control specialists sometimes introduced larvivorous fish into mosquito breeding sites such as ponds, rivers, and communal water bodies. This policy is still used in some countries. This review examines the evidence that larvivorous fish have an effect on the transmission of Plasmodium parasites, and on the presence and density of mosquito larvae in these waters.

Reducing mosquito bites

Insecticide-treated bed nets and curtains for preventing malaria  
Insecticide treated bed nets protect people from malaria by preventing mosquitos from biting them while they sleep, and they are now the mainstay of malaria prevention in endemic areas. This review summarizes the evidence of the impact of insecticide-treated bed nets or curtains on mortality, and malaria illness.

Insecticide-treated nets for preventing malaria in pregnancy
Malaria during pregnancy has additional risks for both the mother and the fetus. This review compares the protective effects of insecticide-treated nets and untreated nets in pregnant women. A version of this review was also published in PLOS Medicine

Indoor residual spraying for preventing malaria
Spraying the inner walls of houses with insecticide (indoor residual spraying) has been a mainstay of malaria prevention programmes for decades. It is thought to reduce malaria transmission by repelling mosquitoes from entering houses and by killing female mosquitoes that are resting inside houses after having bitten someone inside. This review summarizes the available evidence for indoor residual spraying in an effort to quantify the impact of IRS alone, and in combination with insecticide-treated nets.

The Impact of Pyrethroid Resistance on the Efficacy of Insecticide-Treated Bed Nets against African Anopheline Mosquitoes: Systematic Review and Meta-Analysis
In this systematic review in PLOS Medicine, the authors explore whether there is any demonstrable impact of pyrethroid resistance on the efficacy of nets, by examining outcomes at the level of the mosquito.

Electronic mosquito repellents for preventing mosquito bites and malaria infection
Electronic mosquito repellents are marketed to prevent mosquitoes biting and to prevent malaria. They are small handheld, battery-powered devices intended to repel mosquitoes by emitting a high frequency buzz almost inaudible to the human ear. This review assesses whether electronic mosquito repellents prevent mosquito bites and malaria infection.

Reducing malaria transmission

Mass drug administration for malaria 
Mass drug administration (MDA) is the administration of antimalarial drugs to whole populations at risk of the disease, irrespective of whether they have malaria or not. MDA was a historic component of many malaria control and elimination programmes, but is not currently recommended. This review examines the effects of MDA as it is now being reconsidered as a malaria elimination tool.

Primaquine or other 8-aminoquinoline for reducing Plasmodium falciparum transmission
This review assesses whether a single dose or a short course of primaquine or other 8-aminoquinoloine added to treatments for malaria reduces malaria transmission by decreasing gametocytes – the parasite stage infective to mosquitoes – in the blood. This 2014 edition stratifies the evidence by dose level of primaquine.

Preventing malaria in high risk groups

Intermittent preventive treatment for malaria in children living in areas with seasonal transmission
In areas where malaria is common, younger children have repeated episodes of malarial illness, which can sometimes be severe and life-threatening. In areas where malaria is seasonal, a practical policy option is to give drugs to prevent malaria at regular intervals during the transmission season, regardless of whether the child has malaria. This is known as Intermittent Preventive Treatment (IPTc). This review examines the effects of IPTc programmes on the frequency of malaria illness and death.

Drugs for preventing malaria in pregnant women
Malaria contributes to maternal illness and anaemia during pregnancy, especially in first-time mothers, and can harm the baby. To reduce these effects the World Health Organization recommend routinely treating the mother for malaria during the second and third trimesters regardless of whether she has symptoms or not. This is known as intermittent presumptive treatment (IPTp). This review assesses the benefits and harms of this policy compared to no intervention.

Intermittent preventive therapy for malaria during pregnancy using 2 versus 3 or more doses of sulfadoxine-pyrimethamine
The Cochrane review team also contributed to a recent systematic review, which asked a topical question about whether to give three doses of intermittent presumptive treatment to women in malaria areas of Africa during pregnancy rather than two, published in JAMA in 2012.

Intermittent preventive treatment regimens for malaria in HIV-positive pregnant women
Intermittent preventive treatment (IPTp) is recommended for pregnant women living in malaria endemic countries due to benefits for both the mother and baby. However, the impact may not be the same in HIV-positive pregnant women, as HIV infection impairs a woman's immunity. This review compares intermittent preventive treatment regimens for malaria in HIV-positive pregnant women living in malaria-endemic areas.

Malaria chemoprophylaxis in sickle cell disease
Malaria is the most common precipitating cause of crises in sickle cell disease in malaria-endemic countries. Health professionals often recommend life-long malaria chemoprophylaxis for people with sickle cell disease living in these areas. This review assesses the effects of routine malaria chemoprophylaxis in people with sickle cell disease.

Acknowledgements: David Sinclair, Anne-Marie Stephani and Paul Garner for drafting the text and selecting the reviews. This work is funded by UKaid from the UK Government Department for International Development for the benefit of low and middle income countries.

Image credit: CDC/SCIENCE PHOTO LIBRARY, C015/3970

Date published: 25 April 2014

Contact: Cochrane Editorial Unit (editorial-unit@cochrane.org)

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