Malaria

Malaria is caused by Plasmodium parasites. Five species are known to cause the disease in humans: P. falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi. Most infections are transmitted when an infected female Anopheles mosquito bites a person. Transmission through contaminated needles or blood transfusion can also occur, but malaria is not ordinarily passed through casual contact between people. P. falciparum is associated with the most severe disease and accounts for most malaria cases in Africa; P. vivax is widespread outside sub-Saharan Africa and can persist in a dormant liver stage that later causes a relapse.

After an infectious mosquito bite, parasite forms called sporozoites enter the human body and travel to the liver. They multiply there and release merozoites, which infect red blood cells; later blood stages are responsible for the illness's clinical symptoms. Some parasites develop into forms that a mosquito can take up during another blood meal. They reproduce inside the mosquito and eventually produce forms that can infect another person. This cycle between human and mosquito hosts is central to how malaria persists and spreads.

Common early symptoms include fever, chills and headache; nausea, muscle aches and fatigue may also occur. Symptoms often begin within days or weeks of infection, though timing varies by parasite species and can be delayed. Malaria can progress to severe illness, including impaired consciousness, seizures, breathing difficulty or organ complications. Suspected cases need prompt medical assessment: diagnosis is confirmed with parasite-based testing of blood, such as microscopy or a rapid diagnostic test. Early diagnosis and appropriate treatment are important because untreated disease, particularly P. falciparum malaria, can become life-threatening.

Malaria control combines measures aimed at mosquitoes with prevention and care for people. Insecticide-treated nets and indoor residual spraying are major tools for reducing mosquito bites and transmission. Travellers to malaria-risk areas may be advised by a health professional to take preventive medicines, depending on the destination and their circumstances. WHO recommends the RTS,S/AS01 and R21/Matrix-M vaccines for children in areas with moderate to high P. falciparum transmission; vaccination complements rather than replaces other protective measures. Confirmed malaria is treated with antimalarial medicines selected according to the parasite species, illness severity, place of infection and drug sensitivity. Artemisinin-based combination therapies are the most effective treatment for P. falciparum malaria, while resistance to medicines remains an important challenge.

Scientific work has produced new tools while malaria remains difficult to control in many places. In the 1970s, Chinese researcher Tu Youyou studied traditional herbal medicines and isolated artemisinin from sweet wormwood; medicines based on the compound have improved health and saved lives. The 2015 Nobel Prize in Physiology or Medicine recognized her discoveries concerning a novel therapy against malaria. More recently, WHO has recommended two malaria vaccines for use in childhood programmes in parts of Africa, alongside established measures such as nets and preventive treatment. The combination of tools matters because mosquito behavior, local transmission patterns and parasite resistance can change the effectiveness of individual interventions.