Meanwhile, we recently evaluated a DNA-based diagnostic method by the polymerase chain reaction (PCR) targeting the small subunit ribosomal RNA (SSU rRNA) genes of all four species of human malaria as reported (8). Ten isolates each for P. falciparum, P. vivax, and P. malariae and four isolates of P. ovale were used as positive controls. Results showed that all isolates gave concordant positive PCR products with those diagnosed by microscopy except an isolate from this patient (data not shown). Retrospective examination of blood smears has shown several developmental stages of malaria parasites similar to those typically seen in P. malariae. However, some erythrocytes that harbored mature asexual parasites possessed fimbriated margins. The cytoplasm of some young trophozoites appeared spread out into the network of irregular pseudopodia, and the chromatin was distributed into fragments, conforming to the tenue forms. Pinkish dots varying from fine to large irregular masses called Sinton and Mulligan's stippling developed intracorpuscularly with the maturation of some parasites