<P> Infection with P. falciparum may result in cerebral malaria, a form of severe malaria that involves encephalopathy . It is associated with retinal whitening, which may be a useful clinical sign in distinguishing malaria from other causes of fever . Enlarged spleen, enlarged liver or both of these, severe headache, low blood sugar, and hemoglobin in the urine with renal failure may occur . Complications may include spontaneous bleeding, coagulopathy, and shock . </P> <P> Malaria in pregnant women is an important cause of stillbirths, infant mortality, abortion and low birth weight, particularly in P. falciparum infection, but also with P. vivax . </P> <P> Malaria parasites belong to the genus Plasmodium (phylum Apicomplexa). In humans, malaria is caused by P. falciparum, P. malariae, P. ovale, P. vivax and P. knowlesi . Among those infected, P. falciparum is the most common species identified (~ 75%) followed by P. vivax (~ 20%). Although P. falciparum traditionally accounts for the majority of deaths, recent evidence suggests that P. vivax malaria is associated with potentially life - threatening conditions about as often as with a diagnosis of P. falciparum infection . P. vivax proportionally is more common outside Africa . There have been documented human infections with several species of Plasmodium from higher apes; however, except for P. knowlesi--a zoonotic species that causes malaria in macaques--these are mostly of limited public health importance . </P> <P> Global warming is likely to affect malaria transmission, but the severity and geographic distribution of such effects is uncertain . </P>

Which form of malaria is both the most common and the most severe