What is malaria?
Malaria is an infectious disease caused by a parasite, Plasmodium, which infects red blood cells. Malaria is characterized by cycles of chills, fever, pain, and sweating. Historical records suggest malaria has infected humans since the beginning of mankind. The name "mal aria" (meaning "bad air" in Italian) was first used in English in 1740 by H. Walpole when describing the disease. The term was shortened to "malaria" in the 20th century. C. Laveran in 1880 was the first to identify the parasites in human blood. In 1889, R. Ross discovered that mosquitoes transmitted malaria. Of the four common species that cause malaria, the most serious type is Plasmodium falciparum malaria. It can be life-threatening. However, another relatively new species, Plasmodium knowlesi, is also a dangerous species that is typically found only in long-tailed and pigtail macaque monkeys. Like P. falciparum, P. knowlesi may be deadly to anyone infected. The other three common species of malaria (P. vivax, P. malariae, and P. ovale) are generally less serious and are usually not life-threatening. It is possible to be infected with more than one species of Plasmodium at the same time.
What are malaria symptoms and signs?
How is malaria transmitted?
Figure 1: CDC illustration of the life cycles of malaria parasites, Plasmodium spp. SOURCE: CDC
Where is malaria a particular problem?
country_table/a.html) that lists the problem areas in detail.
What is the incubation period for malaria?
How is malaria diagnosed?
|Figure 2: CDC slide of a Giemsa stained smear of red blood cells showing Plasmodium malariae and Plasmodium falciparum parasites. SOURCE: CDC/Steven Glenn, Laboratory & Consultation Division|
Although this test is easily done, correct results are dependent on the technical skill of the lab technician who prepares and examines the slides with a microscope. Other tests based on immunologic principles exist; including RDTs (rapid diagnostic tests) approved for use in the U.S. in 2007 and polymerase chain reaction (PCR) tests. These are not yet widely available and are more expensive than the traditional Giemsa blood smear. Some investigators suggest such immunologic based tests be confirmed with a Giemsa blood smear.
What is the treatment for malaria?
Is malaria a particular problem during pregnancy?
Is malaria a particular problem for children?
How do people avoid getting malaria?
- Avoid outbreaks: To the extent possible, travelers should avoid traveling in areas of known malaria outbreaks. The CDC Travelers' Health web page provides alerts and information on regional disease transmission patterns and outbreak alerts (http://www.cdc.gov/travel).
- Be aware of peak exposure times and places: Exposure to arthropod bites may be reduced if travelers modify their patterns of activity or behavior. Although mosquitoes may bite at any time of day, peak biting activity for vectors of some diseases (for example, dengue, chikungunya) is during daylight hours. Vectors of other diseases (for example, malaria) are most active in twilight periods (for example, dawn and dusk) or in the evening after dark. Avoiding the outdoors or focusing preventive actions during peak hours may reduce risk.
- Wear appropriate clothing: Travelers can minimize areas of exposed skin by wearing long-sleeved shirts, long pants, boots, and hats. Tucking in shirts and wearing socks and closed shoes instead of sandals may reduce risk. Repellents or insecticides such as permethrin can be applied to clothing and gear for added protection; this measure is discussed in detail below.
- Check for ticks: Travelers should be advised to inspect themselves and their clothing for ticks during outdoor activity and at the end of the day. Prompt removal of attached ticks can prevent some infections.
- Bed nets: When accommodations are not adequately screened or air conditioned, bed nets are essential to provide protection and to reduce discomfort caused by biting insects. If bed nets do not reach the floor, they should be tucked under mattresses. Bed nets are most effective when they are treated with an insecticide or repellent such as permethrin. Pretreated, long-lasting bed nets can be purchased prior to traveling, or nets can be treated after purchase. The permethrin will be effective for several months if the bed net is not washed. (Long-lasting pretreated nets may be effective for much longer.)
- Insecticides: Aerosol insecticides, vaporizing mats, and mosquito coils can help to clear rooms or areas of mosquitoes; however, some products available internationally may contain pesticides that are not registered in the United States. Insecticides should always be used with caution, avoiding direct inhalation of spray or smoke.
- Optimum protection can be provided by applying repellents. The CDC recommended insect repellent should contain up to 50% DEET (N,N-diethyl-m-toluamide), which is the most effective mosquito repellent for adults and children over 2 months of age.
What is the prognosis (outcome) for people with malaria?
Where can people get more information about malaria?
- Malaria is a disease caused by Plasmodium spp. parasites that infects about 400 million people per year with about 2 million deaths.
- Symptoms include recurrent cycles (every one to three days) of fever, chills, muscle aches, headaches; nausea, vomiting, and jaundice also may occur.
- Anopheles mosquitoes transmit the parasites to humans when they bite. The parasites undergo a complicated life cycle in both mosquitoes and humans; the cycle begins again when the mosquitoes take a blood meal from a human that is contaminated with mature parasites.
- Africa, Asia, and Central and South America are the areas with high numbers of malarial infections.
- The incubation period for malaria symptoms is about one to three weeks but may be extended to eight to 10 months after the initial infected mosquito bites occur. Some people may have dormant parasites that may get reactivated years after the initial infection.
- Malaria is diagnosed by the patient's history of recurrent symptoms and the identification of the parasites in the patient's blood, usually by a Giemsa blood smear.
- Malaria is usually treated by using combinations of two or more anti-parasite drugs incorporated into pills that are taken before exposure (prophylactic or preventative therapy) or during infection. More serious infections are treated by IV anti-parasitic drugs in the hospital.
- Infants, children, and pregnant females, along with immunodepressed patients are at higher risk for worse outcomes when infected with malaria parasites.
- To reduce the chance of getting malaria, people should avoid malaria-endemic areas of the world, use mosquito repellents, cover exposed skin, and use mosquito netting covered areas when sleeping.
- The prognosis for the majority of malaria patients is good; most recover with no problems, unless infected with P. falciparum or P. knowlesi, which may have fair to poor outcomes unless treated immediately. Infants, children under 5 years of age, pregnant females, and those with depressed immune systems frequently have a fair to poor prognosis unless effectively treated early in the infection.
D'Acremont, V., C. Lengeler, and B. Genton. "Reduction in the Proportion of Fevers Associated With Plasmodium falciparum Parasitaemia in Africa: A Systematic Review." Malaria Journal 9.240 Aug. 22, 2010 doi:10.1186/1475-2875-9-240.
Rottmann, M., C. McNamara, B. Yeung, et al. "Spiroindolones, a Potent Compound Class for the Treatment of Malaria." Science 329 (2010): 1175-1180.
Last Editorial Review: 10/8/2010