**2. The malaria parasite**

Human Malaria is a parasitic disease caused by apicomplexan protozoan (single celled) coccidian. These parasites are haematozoans or haemosporinas of the family plasmodiidae. A contributing factor to the malaria problem in sub-Saharan Africa is the diversity of the parasite that infects humans. Four species infect man of which *Plasmodium falciparium* is the most virulent. The other species are *P. vivax, P. malariae* and *P. ovale. P. falciparium* and *P. vivax* are the most common [3].

In sub-Saharan Africa, *P. falciparium* poses the greatest threat because of its high level of mortality and the complications arising. *P*. *vivax* is worldwide in tropical and some temperate regions. *P*. *vivax* accounts for more than half of all malaria cases outside sub-Saharan Africa. *P. vivax* is unique in that a sporozoite injected into the blood stream may stay in hepatocytes as hyponozoites. *P*. *ovale* is mainly in found in tropical West Africa and *P*. *malariae* is found worldwide but with patchy distribution [3]. These malaria parasites can develop within, invade red blood cells (erythrocytes) and consume up to 75% - 80% of their haemoglobin as nutrient source [1].

For both *P. vivax* and *P. ovale*, clinical relapses may occur weeks to months after the first infection, even if the patient has left the malarious area. These new episodes arise from "dormant" liver forms (absent in *P. falciparum* and *P.malariae*), and special treatment – targeted at these liver stages – is mandatory for a complete cure [3].
