Malaria is an infectious disease caused by a parasite of the genus Plasmodium and transmitted by mosquitoes. According to the National Institute of Allergy and Infectious Diseases, four species of Plasmodium found in Africa and tropical and subtropical countries in Asia, South and Central America and the Middle East infect humans. Malaria causes recurrent symptoms, and its effects can be long-lasting or fatal in some cases.
Malarial infections are characterized by paroxysms, or recurrent attacks, that develop in three stages, according to the National Institute of Allergy and Infectious Diseases (NIAID). The first stage of these attacks is the development of chills. Moderate to severe shaking chills may be accompanied by a headache, general ill feeling (malaise), fatigue, muscle pain, nausea, vomiting and diarrhea. Stage 2, fever, typically develops within an hour or two of initial symptoms and may cause hot and dry skin. As body temperature falls, stage 3, sweating, begins, causing feelings of extreme fatigue and weakness. These symptoms generally appear within ten to 16 days after the infectious mosquito bite and occur as a result of the bursting of infected red blood cells.
According to the NIAID, the presentation of symptoms of malaria may differ depending upon the parasite that caused the infection. Plasmodium falciparum malaria often develops suddenly and is associated with the most severe complications. People with P. falciparum malaria may feel miserable between attacks and may die without treatment. On the other hand, those with Plasmodium vivax malaria, a geographically widespread type of malaria that produces less severe symptoms but that can recur for up to 3 years, may feel fine in between attacks. Plasmodium malariae infections can produce typical malaria symptoms, but the virus may lie dormant in the blood for decades, and even those with no symptoms can spread the infection through blood donation or mosquito bites. Plasmodium ovale infections are very rare (occurring mainly in West Africa) and may cause relapses. Both P. vivax and P. ovale infections are characterized by attacks that recur regularly every two days, while P. malariae is associated with recurrences occurring every three days.
Infection with P. falciparum will most likely to lead to serious, potentially fatal complications. According to the Mayo Clinic, if left untreated, P. falciparum malaria can cause death within hours of infection. Hemolytic anemia, a condition in which the bone marrow is unable to keep up with the pace of red blood cell destruction caused by the infection, may lead to fatigue, weakness, pale skin, rapid heart rate, enlargement of the spleen and shortness of breath, according to the National Institutes of Health (NIH). Cerebral malaria may also occur if infected blood cells block the blood vessels to the brain. Cerebral malaria may lead to swelling of the brain and brain damage.
Other serious side effects of malaria include dehydration, liver or kidney failure and breathing problems caused by fluid in the lungs (pulmonary edema). The NIH notes that rupture of the spleen may lead to internal hemorrhage or bleeding, and spreading infection may also lead to meningitis, an inflammation of the meninges, or membranes, that surround the brain and spinal cord.