Malaria is a life-threatening disease caused by Plasmodium parasites. The parasites are spread to people through the bites of infected female Anopheles mosquitoes, called “malaria vectors”. There are five parasite species that cause malaria in humans, and two of these species – P. falciparum and P. vivax – pose the greatest threat.
Malaria is a preventable and treatable mosquito-borne illness
P. falciparum is the most prevalent malaria parasite on the African continent, responsible for most malaria-related deaths globally.
P. vivax is the dominant malaria parasite in most countries outside of sub-Saharan Africa.
An estimated 3.2 billion people worldwide are at risk for malaria.
In 2015, 95 countries and territories had ongoing malaria transmission.
In 2015 alone, there were an estimated 214 million new cases of malaria and 438,000 deaths (WHO 2015).
Sub-Saharan Africa carries a disproportionately high share of the global malaria burden. In 2015, the region was home to 88% of malaria cases and 90% of malaria deaths, globally.
Nigeria accounted for up to 25 percent of the global cases and deaths.
Malaria is preventable and curable, and increased efforts are dramatically reducing the malaria burden in many places.
Globally, between 2000 and 2015, malaria incidence (the rate of new cases) among populations at risk fell by 37% while malaria death rate fell by 60% among all age groups, and by 65% among children less than 5years.
Transmission: In most cases, malaria is transmitted through the bites of female Anopheles mosquitoes. The intensity of transmission depends on factors related to the parasite, the vector, the human host, and the environment. The female mosquitoes seek a blood meal to nurture their eggs. Malaria epidemics can occur when climate and other conditions suddenly favour transmission in areas where people have little or no immunity to malaria. They can also occur when people with low immunity move into areas with intense malaria transmission, for instance to find work, or as refugees. Human immunity is another important factor, especially among adults in areas of moderate or intense transmission conditions. Partial immunity is developed over years of exposure, and while it never provides complete protection, it does reduce the risk that malaria infection will cause severe disease. For this reason, most malaria deaths in Africa occur in young children, whereas in areas with less transmission and low immunity, all age groups are at risk.
Symptoms: Malaria is an acute febrile illness. In a non-immune individual, symptoms appear 7 days or more (usually 10–15 days) after the infective mosquito bite. The first symptoms – fever, headache, chills and vomiting – may be mild and difficult to recognize as malaria. If not treated within 24 hours, P. falciparum malaria can progress to severe illness, often leading to death. Children with severe malaria frequently develop one or more of the following symptoms: severe anaemia, respiratory distress in relation to metabolic acidosis, or cerebral malaria. In adults, multi-organ involvement is also frequent. In malaria endemic areas, people may develop partial immunity, allowing asymptomatic infections to occur.
Diagnosis/Testing
Prompt parasitological confirmation by microscopy or Rapid Diagnostic Test (RDT) is recommended for all patients with suspected malaria before treatment begins.
Treatment: Artemisinin-based combination therapy (ACT) has become the standard treatment of uncomplicated malaria. More detailed recommendations are available in the “WHO Guidelines for the treatment of malaria”, third edition, published in April 2015.
Prevention: Scientifically proven key prevention interventions include: 1) promotion of insecticide-treated mosquito nets (ITNs) which focuses on the distribution and use of bed nets, called Long Lasting Insecticidal Nets (LLINs); 2) indoor residual spraying (IRS): involves the coordinated, timely spraying of the interior walls of homes with insecticides that kill mosquitoes; 3) intermittent preventive treatment for pregnant women (IPTp): an effective means of reducing the effects of malaria in both the pregnant woman and her unborn child by giving at least two doses of the drug sulfadoxine-pyrimethamine (SP); and 4)Use of antimalarial medicines to prevent malaria. For travellers, malaria can be prevented through chemoprophylaxis, which suppresses the blood stage of malaria infections, thereby preventing malaria disease.
Vaccines against malaria: There are currently no licensed vaccines against malaria or any other human parasite.
*Adapted from Nigeria Centre for Disease Control (www.ncdc.gov.ng)
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