ABSTRACT
Malaria parasites are an extremely successful group of protozoans which infect a large variety of distantly related vertebrate hosts. In this review we limit our discussion to the major human pathogen in the Plasmodium species, P. Jalciparum. During its complex life cycle, P. Jalciparum invades different cell types and propagates in very distinct environ ments such as blood vessels in the human host and the gut, blood lymphe and salivary glands in the mosquito host. Each of these host compartments put a selective pressure on the parasite. Confronted by a particularly complex and variable host interaction, Plasmo dium species have acquired efficient mechanisms that allow them to adapt to changing environments. The ease with which the parasite develops resistance to many anti-malarial drugs demonstrates the potential of P. Jalciparum for dealing with new environmental pressures. One probable major advantage is the fact that Plasmodium infections generate a huge number of blood stage parasites (109 to 1012). This represents a tremendous reservoir for mutations upon which selection can act.
