Plasmodium is a genus of protozoan parasites, many of which are known to cause malaria in humans. Parasites are transmitted between human hosts by female mosquitoes of the genus Anopheles. Plasmodium cannot survive outside of a mosquito or human, so the entire plasmodium life cycle is carried out during the process of transmission and infection. There are several somewhat complex stages in the life cycle of plasmodium, though researchers have been able to accurately trace the pathways and mechanisms parasites use to spawn, mature, thrive, and replicate.
The plasmodium life cycle begins when new cells, called sporozoites, are picked up by a mosquito when it bites an infected person. Sporozoites lie dormant in the saliva of the mosquito until it bites another host. Immature parasites travel in the bloodstream of a human to the liver, where they attach to cells called hepatocytes. Over the course of about nine days, sporozoites mature into their juvenile form called merozoites. It is common for several thousand merozoites to form within only a few liver cells.
Groups of merozoites usually break free from the liver between nine and 20 days after the initial infection. They then invade red blood cells called erythrocytes and use the cells' energy sources to drive asexual reproduction. In about two to four days, infected erythrocytes break open and plasmodium parasites quickly spread to other host cells. Parasites constantly replicate in the bloodstream and new spores can again be picked up by mosquitoes, thus continuing the plasmodium life cycle.
People who are infected with malaria can experience a number of devastating side effects. Anemia is common as parasites cause red blood cells to rupture. Fever, nausea, vomiting, and muscle pain become prevalent as plasmodium spreads throughout the bloodstream. In severe cases, people can experience whole body convulsions, extreme fatigue, or even comas. Lung, liver, or kidney failure is possible if plasmodium spores overtake the majority of red blood cells in the body.
Malaria is often deadly without prompt medical care. Thanks to recent advancements in medicine and new, deeper understandings of the plasmodium life cycle, specialty doctors are usually able to combat the parasites in the early stages of infection. Anti-malarial medications such as chloroquine are generally effective at boosting the immune system's defenses and preventing plasmodium reproduction in the bloodstream. In addition, doctors strongly urge world travelers to receive chloroquine injections before embarking on trips as a form of preventive medicine.