QUESTION:
How does malaria infect the body?
ANSWER:
Malaria is transmitted to humans via certain species of mosquito. The parasite that causes malaria, called Plasmodium (there are several species, which cause slightly different forms of the disease), lives in the saliva of the mosquito and is introduced into the human blood when the mosquito bites through the skin. It is interesting to note that only female mosquitoes transmit malaria; male mosquitoes don’t feed on blood, only on nectar and other plant juices, and their mouth parts are too soft to break human skin!
Once the parasite is in the human bloodstream, it undergoes several different life stages. Throughout, it must evade the human immune system, and it has a number of clever ways to do this. One method is by producing a protein which it attaches to its surface; this acts as a “cloak” against the human immune system and hides the parasite. The parasite also uses other proteins to complete its life cycle, for example several are used to enter red blood cells, where part of the reproductive cycle of the parasite is carried out. Finally, after several transformations and cycles of reproduction, the malaria parasites are released again into the bloodstream, where they can be picked up by another female mosquito, and transported to a different human.
For more information about some of the mechanisms for evading the immune system, check out this article from the BBC website, which summarises some recent findings about Plasmodium falciparum, the malaria parasite which causes some of the most debilitating and deadly malaria cases worldwide.