Assessment of the efficacy of 8 weeks of primaquine for the prevention of relapse in vivax malaria patients using SSCP-PCR and sequencing in south and south-east Iran, 2008–2011

Abstract

Treatment of vivax malaria with primaquine prevents the risk of relapse. This study was designed to assess the efficacy of 8 weeks of primaquine treatment in prevention of relapse in patients with vivax malaria in south and south-east Iran by SSCP-PCR and sequencing. A total of 163 symptomatic vivax malaria cases were followed up in Hormozgan and Sistan, Baluchestan provinces in south and south-east Iran between December 2008 and December 2011. DNA was extracted from primary and secondary positive samples. A variation region of PvMSP-1 gene was selected and amplified by PCR. The obtained fragments were processed in polyacrylamide gel for single-strand conformational polymorphism (SSCP) and then sequenced. Among 145 patients treated with chloroquine plus primaquine who completed the study period, two patients (1.4%) experienced a secondary infection after the initial episode of Plasmodium vivax. The comparison between primary and secondary isolates by SSCP indicated different banding patterns and electrophoretic mobility. Alignment of nucleotide sequences between pair primary and secondary isolates revealed dissimilar homology. Secondary isolates of both patients were considered as reinfection. Five of the 18 cases (28%) treated with chloroquine only revealed secondary infection. Analysis of nucleotide sequences and SSCP patterns indicated the relapse in all of them. This survey indicates that intake of primaquine, 0.75 mg/kg, weekly for 8 consecutive weeks, is effective for the prevention of relapse in vivax cases in Iran.