Persistence of Markers of Chloroquine Resistance in Plasmodium falciparum in Bangladesh

Abstract

The control of malaria, in terms of drug resistance, remains a significant global challenge, with Bangladesh, a malaria-endemic country, being no exception. The aim of this study was to explore antimalarial resistance in Bangladesh by molecular analysis of Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance transporter 1 (pfmdr1) genetic markers of P. falciparum. Samples were obtained from uncomplicated malaria patients between 2009 and 2014 from six malaria-endemic districts. Based on parasite transmission intensity, the endemic districts were divided into high-transmission (Chittagong Hill Tracts [CHT]) and low-transmission (non-CHT) regions. Falciparum malaria-positive isolates were genotyped for K76T of the pfcrt gene, and N86Y and Y184F of the pfmdr1 gene: in total, 262 P. falciparum clinical isolates were analyzed. In CHT areas, the prevalence of polymorphisms was 70.6% for 76T, 14.4% for 86Y, and 7.8% for 184F. In non-CHT areas, 76T and 86Y mutations were found in 78.0% and 19.5% of the samples, respectively, whereas no 184F mutations were observed. We compared our data with previous similar molecular observations, which shows a significant decrease in pfcrt 76T mutation prevalence. No pfmdr1 amplification was observed in any of the samples suggesting an unaltered susceptibility to amino alcohol drugs such as mefloquine and lumefantrine. This study provides an updated assessment of the current status of pfcrt and pfmdr1 gene mutations in Bangladesh, and suggests there is persistent high prevalence of markers of resistance to aminoquinoline drugs.

Figure 1.

Study areas showing the prevalence of both mutant and wild-type alleles at each site. (A) Plasmodium falciparum chloroquine resistance transporter (pfcrt) K76T; (B) Plasmodium falciparum multidrug resistance transporter 1 (pfmdr1) N86Y. This figure appears in color at www.ajtmh.org.

Figure 2.

Proportion comparison of the prevalence of (A) Plasmodium falciparum chloroquine resistance transporter (pfcrt) 76T and (B) Plasmodium falciparum multidrug resistance transporter 1 (pfmdr1) 86Y in the present study with previous published studies^,– from Bangladesh. Samples from non-CHT (Chittagong Hill Tracts) districts (Netrokona, n = 8 and Moulvibazar, n = 16) were not included in this analysis. *P < 0.05, **P < 0.01, ***P < 0.001; proportion comparison test. This figure appears in color at www.ajtmh.org.

Figure 3.

Proportion comparison of the prevalence of Plasmodium falciparum multidrug resistance transporter 1 (pfmdr1) N86, 86Y in the present study with previous published studies^,– from Bangladesh. Samples from non-CHT (Chittagong Hill Tracts) districts (Moulvibazar, n = 2) were not included in this analysis. **P < 0.01; proportion comparison test. This figure appears in color at www.ajtmh.org.