Reappearance of Plasmodium malariae in Suriname?

Plasmodium malariae has not been reported from Suriname since 1979. In 1989 an increasing number of P. vivax infections among Bush-negroes returning from the eastern part of the interior was reported in Paramaribo. A microscopical re-examination of all malaria cases in the eastern part of the country failed to confirm any P. vivax infections, but instead P. malariae infections were diagnosed. A study followed to determine the Duffy blood group antigens of 4 Bush-negroes allegedly with a P. vivax infection in their medical history and of 28 and 32 unselected Bush-negroes and Amerindians respectively. Three of the 4 former Bush-negroes had the FyB antigen, while only 7% of the unselected Bush-negroes had this antigen. This low frequency of the genotype is incompatible with reports of high P. vivax prevalences in Bush-negro populations. The Amerindians tested showed a low proportion of Fy0 genotype, which is compatible with the frequent diagnosis of P. vivax among this ethnic group. Reports of P. vivax infections among Bush-negroes are due to misdiagnosis of P. malariae, emphasizing the need to include all 4 species of human Plasmodium when (re)training microscopists. The question whether P. malariae reappeared in Suriname due to increased contact with the simian reservoir, or was simply missed, is discussed.