Malaria is a mosquito-borne infectious disease of humans and other animals caused by protists (a type of microorganism) of the genus Plasmodium. It begins with a bite from an infected female Anopheles mosquito, which introduces the protists through saliva into the circulatory system. In the blood, the protists travel to the liver to mature and reproduce. Malaria causes symptoms that typically include fever and headache, which in severe cases can progress to coma or death. The disease is widespread in tropical andsubtropical regions in a broad band around the equator, including much of Sub-Saharan Africa, Asia, and the Americas. Five species of Plasmodium can infect and be transmitted by humans. The vast majority of deaths are caused by P. falciparum andP. vivax, while P. ovale, and P. malariae cause a generally milder form of malaria that is rarely fatal. The zoonotic species P. knowlesi, prevalent in Southeast Asia, causes malaria in macaques but can also cause severe infections in humans. Malaria is prevalent in tropical and subtropical regions because rainfall, warm temperatures, and stagnant waters provide habitats ideal for mosquito larvae. Disease transmission can be reduced by preventing mosquito bites by distribution of mosquito nets and insect repellents, or with mosquito-control measures such as spraying insecticides and draining standing water. Despite a need, no effective vaccine currently exists, although efforts to develop one are ongoing. Several medications are available to prevent malaria in travellers to malaria-endemic countries (prophylaxis). A variety of antimalarial medications are available. Severe malaria is treated with intravenous or intramuscular quinine or, since the mid-2000s, the artemisinin derivative artesunate, which is superior to quinine in both children and adults and is given in combination with a second anti-malarial such as mefloquine. Resistancehas developed to several antimalarial drugs; for example, chloroquine-resistant P. falciparum has spread to most malarial areas, and emerging resistance to artemisinin has become a problem in some parts of Southeast Asia. Complications
There are several serious complications of malaria. Among these is the development of respiratory distress, which occurs in up to 25% of adults and 40% of children with severe P. falciparum malaria. Possible causes include respiratory compensation ofmetabolic acidosis, noncardiogenic pulmonary oedema, concomitant pneumonia, and severe anaemia. Acute respiratory distress syndrome (ARDS) may develop in 5–25% in adults and up to 29% of pregnant women but it is rare in young children. Coinfection of HIV with malaria increases mortality. Renal failure is a feature ofblackwater fever, where hemoglobin from lysed red blood cells leaks into the urine. Infection with P. falciparum may result in cerebral malaria, a form of severe malaria that involves encephalopathy. It is associated with retinal whitening, which may be a useful clinical sign in distinguishing malaria from other causes of fever. Splenomegaly, severe headache, hepatomegaly (enlarged liver), hypoglycemia, and hemoglobinuria with renal failure may occur. Cause
Malaria in pregnant women is an important cause of stillbirths, infant mortality and low birth weight, particularly in P. falciparum infection, but also with P. vivax Malaria parasites belong to the genus Plasmodium (phylum Apicomplexa). In humans, malaria is caused by P. falciparum, P. malariae, P. ovale, P. vivax and P. knowlesi.Among those infected, P. falciparum is the most common species identified (~75%) followed by P. vivax (~20%). Although P. falciparum traditionally accounts for the majority of deaths, recent evidence suggests that P. vivax malaria is associated with potentially life-threatening conditions about as often as with a diagnosis of P. falciparum infection.P. vivax proportionally is more common outside of Africa.There have been documented human infections with several species of...
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