Infectious Diseases Travelers' Health Malaria Guide Malaria Guide Symptoms Causes Diagnosis Treatment Causes and Risk Factors of Malaria By Heidi Moawad, MD Heidi Moawad, MD Facebook LinkedIn Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications. Learn about our editorial process Updated on June 24, 2022 Medically reviewed by Lindsay Cook, PharmD Medically reviewed by Lindsay Cook, PharmD LinkedIn Lindsay Cook, PharmD is a board-certified consultant pharmacist. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Parasitic Transmission Less Common Causes Lifestyle Factors Frequently Asked Questions Next in Malaria Guide How Malaria Is Diagnosed Malaria is caused by a parasitic infection, which enters the body through a mosquito bite. As the parasite goes through several life stages in the body, it causes the symptoms of malaria and can lead to the contagious transfer of the disease to other people if you get bitten by a mosquito again while you're infected. Your risk of infection can be increased by certain environmental and lifestyle factors. Explore the common and less common risk factors—they may help you prevent contracting malaria. © Verywell, 2018 Parasitic Transmission There are five species of Plasmodium parasite that contribute to human malaria infections: P. falciparum: The species associated with the most common and most severe form of the infection.P. vivax: Among the most common.P. malariae: Causes a milder form of the illness.P. ovale: Is relatively rare.P. knowlesi: Not as common and is increasingly prevalent in Southeast Asia. The infection enters the human body through the bite of a female Anopheles mosquito, which serves as a vector (carrier). This mosquito can survive in tropical and subtropical climates, and it is primarily in these climates that the disease is transmitted. The mosquito acquires the parasite by biting a person who is infected. How the Parasite Causes Disease All species of the malaria parasite cause a sequence of events to occur throughout the body, which produces the symptoms of the infection. After a malaria-carrying mosquito bites a person, the infective form of the parasite, the sporozoite, enters the person’s liver, where it reproduces and enters a new stage in its life cycle, the merozoite stage.The merozoites, which are produced in the liver, enter the red blood cells. The merozoite form replicates inside red blood cells, causing them to burst, releasing chemicals that produce most of the effects of malaria, such as fevers, chills, and aches. The merozoites that are released when red blood cells burst can travel throughout the body, entering into other red blood cells.Sometimes, more severe effects occur and the parasites or the parasite-infected red blood cells can damage organs of the body, such as the brain, the heart, the lungs, or the kidneys. Less Common Causes There are several situations that are associated with a potentially increased risk of malaria transmission. Immune System Deficiency You can become infected with malaria even if you have a normal immune system, but people who have immune system deficiencies, including HIV, are more likely to experience severe effects of the infection. Pregnancy Women who are pregnant are at increased risk of malaria infection. There are several proposed reasons for this, including a lowered immune system—which can reactivate a previous infection or make it more likely for pregnant women to develop the illness if bitten by a host mosquito. Newborn Babies—Transmission From Their Mother Some babies may be born with malaria infection, having acquired the parasite from the mother, not from a mosquito vector. Blood Transfusion There have been reports of malaria infection spread from one person to another through blood transfusions. In these instances, a blood donor who has acquired an infection, usually from a mosquito vector, typically has not yet developed symptoms of the illness. The transfer of blood cells, which are infected with the parasitic organism, can then allow the parasite to thrive inside the body of the recipient of the blood transfusion. Lifestyle Factors Malaria is an infection that is predominantly spread in certain geographic regions with a tropical climate and an abundance of still water, where the mosquito vector that carries the parasite can survive. Lifestyle factors can play a role in your risk of infection. Living in a Region With a High Rate of Malaria Living in a region that is known for malaria substantially increases the risk of becoming infected. While it has been noted that some people living in regions with a high rate of malaria may become immune, many otherwise healthy people with normal immune systems experience serious complications and may die from the infection. Visiting a Region With a High Rate of Malaria Travelers who visit regions with a high rate of malaria may become infected, particularly because travelers who have not been previously exposed to the infection have not developed immunity to the condition. Environmental Factors Some factors increase exposure to malaria, including a lack of protective clothing, exposed sleeping accommodations, lack of insect repellant, and lack of prophylactic medication. Especially when traveling, do your best to take proper precautions. Frequently Asked Questions Where does malaria occur most often? According to the World Health Organization, most cases and deaths are in sub-Saharan Africa. Malaria can also be found in tropical and subtropical regions in Southeast Asia, the Western Pacific, Eastern Mediterranean, and the Americas. How can you prevent malaria? Ask your doctor whether you should take an antimalarial medication before traveling to an area where malaria is common. You can also prevent mosquito bites by using insect repellent, wearing long sleeves and long pants, and using insecticide-treated mosquito nets over your bed at night. How Malaria Is Diagnosed 10 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Centers for Disease Control and Prevention. Malaria. The Parasite, the Mosquito, and the Disease. In: Institute of Medicine (US) Committee on the Economics of Antimalarial Drugs; Arrow KJ, Panosian C, Gelband H, editors. Saving Lives, Buying Time: Economics of Malaria Drugs in an Age of Resistance. Washington, DC: National Academies Press (US); 2004. Prudêncio M, Rodriguez A, Mota MM. The silent path to thousands of merozoites: the Plasmodium liver stage. Nat Rev Microbiol. 2006;4(11):849-856. doi:10.1038/nrmicro1529 Autino B, Corbett Y, Castelli F, Taramelli D. Pathogenesis of malaria in tissues and blood. Mediterr J Hematol Infect Dis. 2012;4(1):e2012061. doi:10.4084/MJHID.2012.061 Boudová S, Cohee LM, Kalilani-Phiri L, et al. Pregnant women are a reservoir of malaria transmission in Blantyre, Malawi. Malar J. 2014;13:506. Published 2014 Dec 17. doi:10.1186/1475-2875-13-506 Verra F, Angheben A, Martello E, Giorli G, Perandin F, Bisoffi Z. A systematic review of transfusion-transmitted malaria in non-endemic areas. Malar J. 2018;17(1):36. Published 2018 Jan 16. doi:10.1186/s12936-018-2181-0 Schantz-Dunn J, Nour NM. Malaria and pregnancy: a global health perspective. Rev Obstet Gynecol. 2009;2(3):186-192. Maia MF, Kliner M, Richardson M, Lengeler C, Moore SJ. Mosquito repellents for malaria prevention. Cochrane Database Syst Rev. 2018;2(2):CD011595. doi:10.1002/14651858.CD011595.pub2 World Health Organization. Malaria. Centers for Disease Control and Prevention. Malaria. Additional Reading Mbale EW, Moxon CA, Mukaka M, et al. HIV coinfection influences the inflammatory response but not the outcome of cerebral malaria in Malawian children, J Infect. 2016 Sep;73(3):189-99. doi: 10.1016/j.jinf.2016.05.012. Alho RM, Machado KV, Val FF, et al. Alternative transmission routes in the malaria elimination era: an overview of transfusion-transmitted malaria in the Americas, Malar J. 2017 Feb 15;16(1):78. doi: 10.1186/s12936-017-1726-y. By Heidi Moawad, MD Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit