Plasmodium Malariae - Clinical Presentation in Humans

Clinical Presentation in Humans

Plasmodium malariae causes a chronic infection that in some cases can last a lifetime. The P. malariae parasite has several differences between it and the other Plasmodium parasites, one being that maximum parasite counts are usually low compared to those in patients infected with P. falciparum or P. vivax. The reason for this can be accounted for by the lower number of merozoites produced per erythrocytic cycle, the longer 72-hour developmental cycle (compared to the 48-hour cycle of P. vivax and P. falciparum), the preference for development in older erythrocytes and the resulting earlier development of immunity by the human host. Another defining feature of P. malariae is that the fever manifestations of the parasite are more moderate relative to those of P. falciparum and P. vivax and fevers show quartan periodicity. Along with bouts of fever and more general clinical symptoms such as chills and nausea, the presence of edema and the nephrotic syndrome has been documented with some P. malariae infections. It has been suggested that immune complexes may cause structural glomerular damage and that renal disease may also occur. Although P. malariae alone has a low morbidity rate, it does contribute to the total morbidity caused by all Plasmodium species, as manifested in the incidences of anemia, low birth rate and reduced resistance to other infections.

Due to a similarity in the appearances of the pathogens, P. knowlesi infections are often misdiagnosed as P. malariae infections. Molecular analysis is usually required for an accurate diagnosis.