Abstract
A total of 101 P. falciparum positive patients were enrolled from urban population of Kolkata, India to determine the therapeutic efficacy of chloroquine as per 28 days follow-up schedule of WHO, 2003. All parasite strains were analyzed for P. falciparum chloroquine resistance transporter (pfcrt) haplotypes using DNA sequencing methodology. The PCR corrected chloroquine resistant P. falciparum was very high (76.3%, 95% CI 0.642 – 0.832) of which early treatment failure was (10%), and late treatment failure was (66.3%). K76T mutation was found in all parasite strains irrespective of therapeutic outcomes. Both the Venezuelan (SVMNT) and Southeast Asian (CVIET) haplotypes were prevalent in the study population with predominance of South East Asian haplotype (87.1%). The present study showed that incidence of CQ resistant P. falciparum malaria in Kolkata was very high and well above the WHO recommended cut-off level for change of drug policy. Recently introduced Artimisinine Combination Therapy by the Government of India to treat all P. falciparum cases is an appropriate step.
Highlights
During the second half of 20th century chloroquine (CQ) became the antimalarial agent of choice due to its efficacy and low toxicity [1]
The present study was designed to determine the therapeutic efficacy of CQ in P. falciparum malaria in Kolkata and distribution of pfcrt haplotypes in the study area
A very high proportion of P. falciparum cases (76.3%, 95% CI 0.642 – 0.832) were found to be resistant to Chloroquine and importantly about 10% of the total study cases were categorized as early treatment failure (ETF)
Summary
During the second half of 20th century chloroquine (CQ) became the antimalarial agent of choice due to its efficacy and low toxicity [1]. The resistance to CQ was developed in Plasmodium falciparum and subsequently spread over almost all the endemic areas of the world. From India, CQ-resistant P. falciparum was first reported in 1973 from Diphu area of Karbi Anglong district of Assam [3]. As the CQ-resistance has reached significantly high levels, National Vector Born Disease Control Programme (NVBDCP) has recently introduced Artemisinin Combination Therapy (ACT) for the treatment of uncomplicated falciparum malaria throughout India. P. falciparum CQR is suggested to involve mechanisms whereby pH sensitive physiologic processes inhibit formation of toxic CQhaematin complexes in favor of haemozoin [15] or CQ efflux reduces drug concentration to the levels that are no longer parasiticidal [16,17,18]
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