Plasmodium vivax
Plasmodium vivax is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring (Benign tertian) malaria, "P. vivax" is one of the five species of malaria parasites that commonly infect humans. Although it is less virulent than "Plasmodium falciparum", the deadliest of the five human malaria parasites, "P. vivax" malaria infections can lead to severe disease and death, often due to splenomegaly (a pathologically enlarged spleen). "P. vivax" is carried by the female "Anopheles" mosquito; the males do not bite.
Plasmodium
In addition to a vertebrate host, all "Plasmodium" species also infect a bloodsucking insect host, generally a mosquito (although some reptile-infecting parasites are transmitted by sandflies). Mosquitoes of the genera "Culex", "Anopheles", "Culiseta", "Mansonia" and "Aedes" act as insect hosts for various "Plasmodium" species. The best studied of these are the "Anopheles" mosquitoes which host the "Plasmodium" parasites of human malaria, as well as "Culex" mosquitoes which host the "Plasmodium" species that cause malaria in birds. Only female mosquitoes are infected with "Plasmodium", since only they feed on the blood of vertebrate hosts. Different species affect their insect hosts differently. Sometimes, insects infected with "Plasmodium" have reduced lifespan and reduced ability to produce offspring. Further, some species of "Plasmodium" appear to cause insects to prefer to bite infected vertebrate hosts over non-infected hosts.