DNA extracted from malaria patients and amplified by nested PCR. Assays of sensitivities, using genus- and species-specific primer sets. (A) DNA by FTA Elute card. Lanes 1 & 3-11, positive samples, Plasmodium genus fragment (240 bp); 2, molecular marker 100 bp (Promega). (B) DNA by rapid boiling technique. Lanes 2-6 & 13-14, Plasmodium genus fragment (240 bp). DNA by FTA classic cards. Lanes 7-12, Plasmodium genus fragment (240 bp). Lane 1, molecular marker 100 bp (Promega). (C) Species-specific primers. Lanes 2-4, P. vivax fragment (117 bp); 5-15, negative results; 1, molecular marker 100 bp (Promega). (D) Species-specific primers in 3 samples; sample 1, lanes 1-4; sample 2, lanes 10-13 showing mixed infections with P. falciparum and P. vivax; sample 3, lanes 6-9 showing single infection with P. falciparum. Each sample was run against the 4 species primer sets. Lanes 1, P. falciparum fragment (205 bp); 2, P. ovale primer (negative); 3, P. malariae primer (negative); 4, P. vivax fragment (117 bp); 5, molecular marker 100 bp (Promega); 6, P. falciparum fragment (205 bp); 7, P. ovale primer (negative); 8, P. malariae primer (negative); 9, P. vivax fragment (negative); 10, P. falciparum fragment (205 bp); 11, P. ovale primer (negative); 12, P. malariae primer (negative); 13, P. vivax fragment (117 bp).