Original Article In vivo Susceptibility of Plasmodium vivax to Chloroquine in Southeastern Iran

Background: Plasmodium vivax is the predominant species causes of malaria with about 90 % total annual reported malaria in Iran. This study conducted to determine the susceptibility of Plasmodium vivax isolates to chloroquine in Sistan and Balochistan Province, southeastern Iran. Methods: A total 270 subjects with symptomatic malaria and confirmed P. vivax infection completed the designed 28-day in vivo study. The thick and thin film blood smears were screened for malaria parasites by microscopy. The nested PCR was applied using the Plasmodium 18 subunit ribosomal ribonucleic (Ssr RNA) genes for detecting mixed infections and diagnosis of parasites in the samples with low parasite on days 0, 5, 6, 7, and 28. Results: P. vivax was cleared in 15%, 50%, 95%, and 100 % of patients on days 1, 2, 3, 4 respectively by microscopy assessment. Six patients were exhibited specific P. vivax band in nested PCR on day 5. No recurrence was observed on days 7, 14 and 28. Mean (±standard deviation) parasite clearance time was 2.41 (±0.8) days. Conclusion: P. vivax is still susceptible to chloroquine in Southeatern Iran. This finding is compati