Background: Malaria is an important parasitic vector-borne disease with considerable infectivity and world-wide distribution. Since prevalence of chloroquine resistance in Plasmodium falciparum at the malarious areas such as Iran and reliable reports from many countries indicating emergence of chloroquine- resistant strains of P.vivax, this study was conducted to monitor the current response of vivax and falciparum plasmodia to chloroquine in Bandar-Abbas district, a malarious area in Iran.
Methods: The study was conducted at the Bandar-Abbas district in Hormozgan province, Iran. 123 patients were enrolled and considered. The patients were treated with a standard 3-day regimen of chloroquine and were followed-up clinically and parasitologically. The results were interpreted as mean parasite clearance time (MPCT) in P. vivax and early treatment failure (ETF), late treatment failure (LTF) and adequate clinical and parasitological response (ACPR) in P. falciparum.
Results: The patients with vivax malaria were responded to the regimen of chloroquine within 24-216 hours. Most cases of the parasite clearance time occurred at 48 hours (50.40%), and less of them at 120, 168, 192 and 216 hours with 0.81% for each of them. MPCT in this study was calculated as 61.07 (±26/47) hours for all of the patients. 33.33% and 66.66% of the patients with falciparum malaria were found at ACPR and LTF groups, respectively.
Conclusion: This study confirms the efficacy of chloroquine on P.vivax. The extended parasite clearance time in a number of patients may be an early sign for reduced susceptibility of P.vivax to chloroquine in the studied areas. Most of the patients with falciparum malaria (66.66%) considered in this study did not respond to the regimen of chloroquine because of chloroquine- resistance in P.falciparum at the area.