ABSTRACT
A mutation -specific PCR assay was used to determine the dynamics of pyrimethamine-resistant P. falciparum parasites in sulphadoxine-pyrimethamine treated children; 0-5 years; from a village in Tanzania. The assay is based on the observation that a point mutation in the dihydrofolate reductase (DHFR) gene confers resistance to pyrimethamine. The PCR assay was used on blood samples collected from treated children on days 0;2;7;14;21and 28. Preliminary results revealed that pyrimethamine-sensitive parasites seemed to be completely cleared after 7 or 14 days of treatment but re-surfaced after 21 days. It was observed that in those children without mixed infection on day 0; pyrimethamine-resistant parasites appeared after 7 days. The implifications of these findings are discussed