Malaria prophylaxis refers to measures used to prevent malaria infection in individuals at risk of exposure to Plasmodium parasites transmitted by Anopheles mosquitoes. These measures include mosquito bite avoidance strategies and the use of antimalarial medications taken before, during, and after exposure. Prophylactic medication is commonly recommended for travelers to endemic regions and for certain populations living in areas with ongoing malaria transmission. The choice of prophylactic strategy depends on factors such as geographic location, parasite resistance patterns, patient characteristics, and duration of exposure.
Several malaria vaccines are under development, and while current vaccines are somewhat effective, more research is needed for sustained malaria control.
Malaria prophylaxis at a large scale has been hindered by barriers to funding and cultural barriers within Africa. The barriers to funding include disruptions in foreign aid, such as decreases in US funding, and persistent corruption within the mostly African countries the aid is flowing to. The cultural barriers include a varying local beliefs that certain medications cannot be trusted or that alternative medicine should be used in place of Western medicine. However, programs are in place to increase malaria awareness at national and local levels in these countries.
Most adults from endemic areas have a degree of long-term infection, which tends to recur, and also possess partial immunity (resistance); the resistance reduces with time, and such adults may become susceptible to severe malaria if they have spent a significant amount of time in non-endemic areas. They are strongly recommended to take full precautions if they return to an endemic area.
Strategies for prevention
Bite prevention—clothes that cover as much skin as possible, insect repellent, insecticide-impregnated bed nets and indoor residual spraying Chemoprophylaxis—chemical treatment of the disease
Continual improvements in malaria prevention strategies have further enhanced its effectiveness in combating areas highly infected with the malaria parasite. The World Health Organization (WHO) recommends both vector control, or the prevention of mosquito contact, and various chemotherapies, including treatments during and after pregnancy, to best prevent malaria occurrences.
Bite prevention Mosquito bite avoidance is a core component of malaria prophylaxis because malaria is transmitted exclusively through the bites of infected female Anopheles mosquitoes. Preventive measures include the use of insecticide-treated bed nets, topical insect repellents containing DEET or picaridin, and protective clothing that minimizes exposed skin. Indoor residual spraying with insecticides has also been shown to reduce malaria transmission in endemic regions. Bite avoidance strategies are particularly important in areas where antimalarial drug resistance limits the effectiveness of chemoprophylaxis.
Medications In choosing the agent, it is important to weigh the risk of infection against the risks and side effects associated with the medications.
Disruptive prophylaxis An experimental approach involves preventing the parasite from binding with red blood cells by blocking calcium signalling between the parasite and the host cell. Erythrocyte-binding-like proteins (EBLs) and reticulocyte-binding protein homologues (RHs) are both used by specialized P. falciparum organelles known as rhoptries and micronemes to bind with the host cell. Disrupting the binding process can stop the parasite.
Monoclonal antibodies were used to interrupt calcium signalling between PfRH1 (an RH protein), EBL protein EBA175 and the host cell. This disruption completely stopped the binding process.
Suppressive prophylaxis Chloroquine, proguanil, mefloquine, and doxycycline are suppressive prophylactics. This means that they are only effective at killing the malaria parasite once it has entered the erythrocytic stage (blood stage) of its life cycle, and therefore have no effect until the liver stage is complete. That is why these prophylactics must continue to be taken for four weeks after leaving the area of risk.
Mefloquine, doxycycline, and atovaquone-proguanil appear to be equally effective at reducing the risk of malaria for short-term travelers and are similar with regard to their risk of serious side effects. Mefloquine is sometimes preferred due to its once a week dose, however mefloquine is not always as well tolerated when compared with atovaquone-proguanil. There is low-quality evidence suggesting that mefloquine and doxycycline are similar with regards to the number of people who discontinue treatments due to minor side effects. People who take mefloquine may be more likely to experience minor side effects such as sleep disturbances, depressed mood, and an increase in abnormal dreams. There is very low quality evidence indicating that doxycycline use may be associated with an increased risk of indigestion, photosensitivity, vomiting, and yeast infections, when compared with mefloquine and atovaquone-proguanil.
Chemoprophylaxis Antimalarial chemoprophylaxis involves the use of medications to prevent malaria infection or suppress parasitemia following exposure to Plasmodium species. Commonly used prophylactic agents include atovaquone-proguanil, doxycycline, mefloquine, and chloroquine, depending on regional resistance patterns.. Some medications act as suppressive prophylaxis by targeting blood-stage parasites, while others provide causal prophylaxis by acting on liver-stage parasites. Selection of an appropriate prophylactic regimen requires consideration of drug side effects, contraindications, patient adherence, and travel itinerary.
Causal prophylaxis Causal prophylactics target not only the blood stages of malaria, but the initial liver stage as well. This means that the user can stop taking the drug seven days after leaving the area of risk. Malarone and primaquine are the only causal prophylactics in use.
Regimens
Specific regimens are recommended by the WHO,The World Health Organization provides country-specific advice on malaria prevention. UK HPA2007 guidelines are available from the UK Health Protection Agency website as a PDF file and includes detailed country-specific information for UK travellers. and CDCthe Centers for Disease Control and Prevention website hosts constantly updated country-specific information on malaria. The advice on this website is less detailed, is very cautious and may not be appropriate for all areas within a given country. This is the preferred site for travellers from the US. for prevention of P. falciparum infection. HPA and WHO advice are broadly in line with each other (although there are some differences). CDC guidance frequently contradicts HPA and WHO guidance.
These regimens include: doxycycline 100 mg once daily (started one day before travel, and continued for four weeks after returning); mefloquine 250 mg once weekly (started two and a half weeks before travel, and continued for four weeks after returning); atovaquone/proguanil (Malarone) 1 tablet daily (started one day before travel, and continued for one week after returning). Can also be used for therapy in some cases.
In areas where chloroquine remains effective: chloroquine 300 mg once weekly, and proguanil 200 mg once daily (started one week before travel, and continued for four weeks after returning); hydroxychloroquine 400 mg once weekly (started one to two weeks before travel and continued for four weeks after returning)
What regimen is appropriate depends on the person who is to take the medication as well as the country or region travelled to. This information is available from the UK HPA, WHO or CDC (links are given below). Doses depend also on what is available (e.g., in the US, mefloquine tablets contain 228 mg base, but 250 mg base in the UK). The data is constantly changing and no general advice is possible.
Doses given are appropriate for adults and children aged 12 and over.
Other chemoprophylactic regimens that have been used on occasion: Dapsone 100 mg and pyrimethamine 12.5 mg once weekly (available as a combination tablet called Maloprim or Deltaprim): this combination is not routinely recommended because of the risk of agranulocytosis; Primaquine 30 mg once daily (started the day before travel, and continuing for seven days after returning): this regimen is not routinely recommended because of the need for G-6-PD testing prior to starting primaquine (see the article on primaquine for more information). Quinine sulfate 300 to 325 mg once daily: this regimen is effective but not routinely used because of the unpleasant side effects of quinine.
Prophylaxis against Plasmodium vivax requires a different approach given the long liver stage of this parasite. This is a highly specialist area.
Vaccines
In November 2012, findings from a Phase III trials of an experimental malaria vaccine known as RTS,S reported that it provided modest protection against both clinical and severe malaria in young infants. The efficacy was about 30% in infants 6 to 12 weeks of age and about 50% in infants 5 to 17 months of age in the first year of the trial.
The RTS,S vaccine was engineered using a fusion hepatitis B surface protein containing epitopes of the outer protein of Plasmodium falciparum malaria sporozite, which is produced in yeast cells. It also contains a chemical adjuvant to boost the immune system response. The vaccine is being developed by PATH and GlaxoSmithKline (GSK), which has spent about $300 million on the project, plus about $200 million more from the Bill and Melinda Gates Foundation.
Preventative chemotherapy in endemic regions
In malaria-endemic regions, preventive chemotherapy is used to reduce malaria morbidity and mortality in high-risk populations. Seasonal malaria chemoprevention is recommended for children in areas with highly seasonal transmission patterns. Intermittent preventive treatment is used during pregnancy and infancy to reduce adverse outcomes associated with malaria infection. These population-level strategies complement vector control measures and are a key component of global malaria control effort.
Barriers to prevention A variety of factors combine to make malaria prophylaxis more difficult to achieve. These mainly fall into two categories: issues with funding and issues with cultural acceptance of treatments.
Funding
Corruption Although funding for malaria prevention has increased dramatically beginning around 2001, corruption has hindered efforts to ensure all funding goes to the proper places. Examples of this corruption are found in multiple countries across Africa.
Uganda has had funding from Global Fund to Fight AIDS, Tuberculosis and Malaria cut in 2005 and 2007 due to continual thefts of grant money. It was audited in 2008/2009 by the Global Fund and deemed an unsafe location for Global Fund resources. A further audit in 2015 exposed more corruption, including stolen drugs and use of expired test kits for HIV. A 2017 clarification by the Global Fund admitted that some, but not all, of the suspected corruption was due to management error. However, there has been no indication that the systemic corruption will stop soon. Burkina Faso was investigated by the Global Fund in 2010 for misuse of grants for insecticide-treated mosquito nets. The investigation found that the total amount of misappropriated funds was €9 million. Difficulties with the stability of the Burkina Faso government have resulted in issues retrieving the lost money. Nigeria had a $100 million loan from the Islamic Development Bank stopped in May 2025 because of an investigation into the Nigerian company using the money, which was subsequently found guilty of collusion in obtaining the contract.
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