QUESTION
What is the life cycle of malaria?
ANSWER
The life cycle of malaria is complex, involving a definitive host, or vector, which for human malaria is a mosquito of the genus Anopheles, and also a human host. Inside both, the malaria parasite undergoes several different transformations and reproductive cycles, which are detailed in the schematic below.
You may also view a video of malaria life cycle.
Schematic of malaria life cycle, courtesy of CDC (www.cdc.gov)
QUESTION
What is the life cycle of malaria?
ANSWER
Malaria is caused by a single celled organism in the genus Plasmodium. Five species of Plasmodium infect humans, but all follow a very similar life cycle, including two separate cycles of asexual reproduction in the human host (one in the liver, called the exo-erythrocytic cycle, and one in the blood, and specifically inside red blood cells, known as the erythrocytic cycle) and a sexual reproductive stage inside the mosquito definitive host (usually called the “vector”). A schematic of the full life cycle is below, courtesy of the CDC (www.cdc.gov).
Schematic of the malaria life cycle, courtesy of CDC (www.cdc.gov)
QUESTION
Where are malaria parasites classified?
ANSWER
The parasite that causes malaria comes from the genus Plasmodium, which is part of a Phylum of single-celled protist organisms called Apicomplexa. The Apicomplexans mostly posses an organ called an apicoplast, which is part of an apical structure designed to aid entry into a host cell. The Apicomplexa is split into two Classes, of which Plasmodium belongs to the Aconoidasida (lacking a structure called a conoid, which is like a set of microtubules), and then to the Order Haemosporidia, which contains parasites which invade red blood cells. Within this Order, Plasmodium belongs to the Family Plasmodiidae, which all share numerous characteristics, including asexual reproduction in a vertebrate host and sexual reproduction in a definitive host (a mosquito, in the case of the Plasmodium species that infect all mammals, including humans).
In the case of human malarias, the definitive host is often referred to as the vector. The family contains about twelve genera, of which one is Plasmodium, which itself is now often divided up into numerous sub-genera, and then again into hundreds of different species, of which five infect humans (P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi).
QUESTION
What are the three stages of malaria?
ANSWER
The three parts of the malaria life cycle are known as the exo-erythrocytic cycle, the erythrocytic cycle and the sporogonic cycle. The first two of these take place in the human (or other mammal) host, while the third occurs in the mosquito vector. The below diagram, courtesy of the CDC, shows the complete life cycle of malaria in more detail.
Schematic of the malaria life cycle, courtesy of the CDC (www.cdc.gov)
QUESTION
What is a malaria parasite?
ANSWER
A malaria parasite is a single-celled protozoan of the genus Plasmodium. These parasites have a complex life-cycle, which involves sexual reproduction in a mosquito vector, plus cycles of asexual reproduction and multiplication in a human host (or other animal – other primates, rodents, birds and reptiles can also be infected with Plasmodium parasites). A diagram of the life cycle is below, courtesy of CDC.
QUESTION
Which mosquito causes malaria?
ANSWER
Map of the main global mosquito vectors of malaria (image courtesy of CDC)
It is important to note that mosquitoes do not CAUSE malaria—the disease itself is caused by microscopic, single-celled animals called Plasmodium. These Plasmodium parasites live and reproduce inside the mosquito, and when the mosquito bites a person, the parasites are transferred into that person’s blood via the mosquito’s saliva. If another mosquito bites a person with malaria, they will pick up the parasites from the person’s blood, and the cycle continues.
Malaria parasites are simply transmitted by mosquitoes, and specifically of the genus Anopheles, of which a variety of different species are capable of transmitting it to humans. In Africa, the species most responsible for transmission is An. gambiae, which actually consists of a group of very similar and closely related species; the group as a whole is known as the An. gambiae species complex. An. funestus is also a wide-spread and important vector species in Africa. Below is a map, courtesy of the CDC, which shows the distribution of some of the main malaria vector mosquitoes worldwide.