Fig. 1.

Prevalence of P. falciparum pyrimethamine- and cycloguanil-resistant DHFR mutants in human blood. Finger-prick samples were obtained from humans with microscopic parasitemia (blood film-positive; n = 86; A) and submicroscopic parasitemia (blood film-negative; n = 88; B). DNA was PCR amplified and analyzed for allele-specific polymorphisms by restriction digestion. y-axis numerals denote DHFR codons. Represented are WT, pyrimethamine-resistant mutants (S108N, N51I, C59R, and triple mutants), cycloguanil-resistant mutants (S108T, A16V, and double mutant), and mixed alleles (WT+S108T or S108N+S108T).