[Studies on detection of Plasmodium falciparum and Plasmodium vivax in blood samples by multiplex polymerase chain reaction]

Abstract

Aim: To establish a sensitive and specific PCR-based method to detect Plasmodium falciparum and P. vivax in blood samples in a single amplification reaction.

Methods: Malaria parasite DNA in blood was amplified by the multiplex polymerase chain reaction using two sets of primers derived from the P. f. moderately-repetitive DNA sequence and COIII gene of P.v.

Results: A 206-bp product for P. f. and a 370-bp product for P.v. were amplified by multiplex PCR, being able to detect parasitemia level as low as 5 x 10(-7) for P. f. and 1.02 x 10(-6) for P. v. and having no cross-reaction with human leucocyte DNA. A total of 783 blood samples on the filter paper collected from patients attending to malaria clinics in malaria endemic areas were detected. The positive rate of multiplex PCR was 85.8%, the misdiagnosis rate was 0, and the under-diagnosis rate was 0.1%, while these three rates of microscopic examination were 84.9%, 3.1% and 1.0%, respectively. The concordance between the two methods was 95.8%.

Conclusion: The multiplex PCR method made the malaria detection more sensitive and specific than the microscopic examination and should be suitable for the diagnosis of malaria in mixed endemic areas, large-scale epidemiological studies, follow-up of drug treatment and donor blood screening.