The Plasmodium falciparum chloroquine resistance transporter (Pfcrt) K76T mutation and haplotype (amino acids 72-76) and the P. falciparum multidrug resistance 1 (Pfmdr1) mutation (N86Y) were analyzed as markers of chloroquine resistance in the DNAs of 73 blood samples from patients with P. falciparum malaria in India. Seventy of the 73 DNAs had the Pfcrt K76T mutation. Of these, 66 had the SVMNT haplotype and four had CVIET, the African/Southeast Asian haplotype. Only 20 of 69 DNAs had the Pfmdr1 N86Y mutation. It is surprising that the Pfcrt haplotype in India is predominantly SVMNT, rather than that seen in Southeast Asia. The widespread prevalence of the Pfcrt K76T mutation is a cause for concern.

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A cross-sectional study was conducted in a malaria hyperendemic state of India to ascertain the distribution of Plasmodium falciparum genotypes in patients with mild (n=40) and severe (n=35) malaria. PCR and nested PCR were used to determine the glutamate-rich protein (GLURP), merozoite surface proteins 1 and 2 (MSP1 and MSP2) and knob-associated histidine-rich protein (KAHRP) for characterization of the parasite. The results indicate that (i) the 200bp allele of the MAD20 family of MSP1 and the 550bp allele of the 3D7 family of MSP2 show over-representation in severe malaria cases; (ii) the multiplicity of infection with respect to MSP2 alleles is significantly higher (P<0.001) in severe cases than in mild cases; and (iii) comparison with the findings of other studies leads to the conclusion that the distribution of P. falciparum genotypes between different clinical groups differs geographically.

BackgroundWith the documentation of cases of falciparum malaria negative by rapid diagnostic tests (RDT), though at low frequency from natural isolates in a small pocket of Odisha, it became absolutely necessary to investigate the status of HRP-2 based RDT throughout the state and in different seasons of the year.MethodsSuspected individuals were screened for malaria infection by microscopy and RDT in 25/30 districts of Odisha, India. Discrepancies in results were confirmed by PCR. False negative RDT samples for Plasmodium falciparum mono-infection were evaluated for detection of HRP2 antigen in ELISA and genotyped for pfhrp2, pfhrp3 and their flanking genes. Multiplicity of infection was ascertained based on msp1 and msp2 genotyping and parasitaemia level was determined by microscopy.ResultsOf the total 1058 patients suspected for malaria, 384 were microscopically confirmed for P. falciparum mono-infection and RDT failure was observed in 58 samples at varying proportion in different regions of the state. The failure in detection was due to undetectable level of HRP-2. Although most of these samples were screened during rainy season (45/345), significantly high proportion (9/17) of RDT negative samples were obtained during the summer compared to rainy season (P = 0.0002; OR = 7.5). PCR genotyping of pfhrp2 and pfhrp3 in RDT negative samples showed 38/58 (65.5) samples to be pfhrp2 negative and 24/58 (41.4) to be pfhrp3 negative including dual negative in 17/58 (29.3). Most of the RDT negative samples (39/58) were with single genotype infection and high proportions of pfhrp2 deletion (7/9) was observed in summer. No difference in parasitaemia level was observed between RDT positive and RDT negative patients.ConclusionHigh prevalence of parasites with pfhrp2 deletion including dual deletions (pfhrp2 and pfhrp3) is a serious cause of concern, as these patients could not be given a correct diagnosis and treatment. Therefore, HRP2-based RDT for diagnosing P. falciparum infection in Odisha is non-reliable and must be performed in addition to or replaced by other appropriate diagnostic tools for clinical management of the disease.Electronic supplementary materialThe online version of this article (10.1186/s12936-018-2502-3) contains supplementary material, which is available to authorized users.