Detection of in-vivo chloroquine resistance inPlasmodium falciparumfrom Rameswaram Island, a pilgrim centre in southern India

Malaria Elimination in Two Endemic Coastal Environments of Southern India: An Eco-Epidemiological Analysis from 2004 to 2019

PURPOSE

Presently, India is heading towards malaria elimination. In this context, analysing malaria epidemiological data of endemic pockets is important. In the present investigation, malaria prevalence in two endemic coastal localities of India viz., Besant Nagar (Chennai district) and Pamban (Ramanathapuram district) was analysed from 2004 to 2019 and correlated with the highest maximum temperature.

METHODS

Malaria surveillance data and entomological data from the malaria clinics were used to investigate epidemiological parameters. The annual malaria cases were correlated with the highest maximum temperature.

RESULTS

The analysis showed that the malaria case (P.v. and P.f.) reports were directly proportional to the temperature increase. Malaria cases were remarkably increased from 2004 to 2011 and subsequently, both Plasmodium vivax and Plasmodium falciparum cases were drastically reduced till 2019. P. vivax was higher than P. falciparum and the male population was found to be more affected. Mixed infection of P. vivax and P. falciparum was observed only in the Besant Nagar site (0.3%). The most affected age group was the adult age group (15 years and above) in both Besant Nagar (76.1%) and Pamban (69.5%).

CONCLUSION

Improved surveillance, complete treatment and integrated vector control activities correlated with a declining trend of malaria cases in both the coastal sites towards malaria elimination.

Polymorphisms in Pfcrt and Pfmdr-1 genes after five years withdrawal of chloroquine for the treatment of Plasmodium falciparum malaria in West Bengal, India

BACKGROUND

The emergence of resistant power against different antimalarial agents particularly by Plasmodium falciparum is a challenge to combat malaria. Regular monitoring is essential not only to determine the efficacy and development of resistance by the parasite but also to detect early sign of regaining sensitivity to any anti-malarial agent that has been withdrawn for a long period. Studies on molecular markers associated with antimalarial drug resistance of prevailing Plasmodium population play an important role in this aspect. The present protocol was designed to study the polymorphisms in pfcrt and pfmdr-1 gene to determine any sign of regaining sensitivity to chloroquine among P. falciparum after five years of artemisinin combination therapy (ACT) implementation.

METHODS

Clinical isolates were collected from P. falciparum positive patients attending the malaria clinic of Calcutta School of Tropical Medicine during December 2014 to December 2015. Genomic parasitic DNA was extracted and subjected to sequencing of pfcrt and pfmdr-1 gene directly from purified PCR products.

RESULTS

A total of 89 isolates were sequenced for pfcrt and 73 isolates for pfmdr-1 genes. In pfcrt gene mutant K76T was detected in all isolates and all were SVMNT haplotype. Out of three important polymorphisms in pfmdr-1 gene mutant Y184F was detected among all isolates. One synonymous G182G and one non-synonymous S232F/Y, mutation were detected in 99% isolates.

CONCLUSION

All isolates carrying mutant K76T in pfcrt gene, considered as hall mark for CQ resistance, indicate that there is no sign of regaining CQ sensitivity among the prevailing P. falciparum population of the study area after five years of ACT implementation.

Mutant pfcrt "SVMNT" haplotype and wild type pfmdr1 "N86" are endemic in Plasmodium vivax dominated areas of India under high chloroquine exposure

Background

Chloroquine resistance (CQR) phenotype in Plasmodium falciparum is associated with mutations in pfcrt and pfmdr-1 genes. Mutations at amino acid position 72-76 of pfcrt gene, here defined as pfcrt haplotype are associated with the geographic origin of chloroquine resistant parasite. Here, mutations at 72-76 and codon 220 of pfcrt gene and N86Y pfmdr-1 mutation were studied in blood samples collected across 11 field sites, inclusive of high and low P. falciparum prevalent areas in India. Any probable correlation between these mutations and clinical outcome of CQ treatment was also investigated.

Methods

Finger pricked blood spotted on Whatman No.3 papers were collected from falciparum malaria patients of high and low P. falciparum prevalent areas. For pfcrt haplotype investigation, the parasite DNA was extracted from blood samples and used for PCR amplification, followed by partial sequencing of the pfcrt gene. For pfmdr-1 N86Y mutation, the PCR product was subjected to restriction digestion with AflIII endonuclease enzyme.

Results

In 240 P. falciparum isolates with reported in vivo CQ therapeutic efficacy, the analysis of mutations in pfcrt gene shows that mutant SVMNT-S (67.50%) and CVIET-S (23.75%) occurred irrespective of clinical outcome and wild type CVMNK-A (7.91%) occurred only in adequate clinical and parasitological response samples. Of 287 P. falciparum isolates, SVMNTS 192 (66.89%) prevailed in all study sites and showed almost monomorphic existence (98.42% isolates) in low P. falciparum prevalent areas. However, CVIETS-S (19.51%) and CVMNK-A (11.84%) occurrence was limited to high P. falciparum prevalent areas. Investigation of pfmdr-1 N86Y mutation shows no correlation with clinical outcomes. The wild type N86 was prevalent in all the low P. falciparum prevalent areas (94.48%). However, mutant N86Y was comparably higher in numbers at the high P. falciparum prevalent areas (42.76%).

Conclusions

The wild type pfcrt gene is linked to chloroquine sensitivity; however, presence of mutation cannot explain the therapeutic efficacy of CQ in the current scenario of chloroquine resistance. The monomorphic existence of mutant SVMNT haplotype, infer inbreeding and faster spread of CQR parasite in areas with higher P. vivax prevalance and chloroquine exposure, whereas, diversity is maintained in pfcrt gene at high P. falciparum prevalent areas.

Efficacy of chloroquine and sulphadoxine-pyrimethamine either alone or in combination before introduction of ACT as first-line therapy in uncomplicated Plasmodium falciparum malaria in Jalpaiguri District, West Bengal, India

OBJECTIVE

In India, till recently, Chloroquine was used as first-line therapy in areas with Chloroquine sensitive Plasmodium falciparum malaria cases. The National Vector Borne Disease Control Programme (NVBDCP) has introduced artemisinin combination therapy (ACT) as first-line option to treat all P. falciparum cases in the country. This study was carried out to ascertain the efficacy of Chloroquine and Sulphadoxine-Pyrimethamine, either alone or in combination, before the launch of ACT by NVBDCP.

METHODS

A total of 300 P. falciparum malaria cases were enrolled randomly in three study arms, Chloroquine (CQ), Sulphadoxine-Pyrimethamine (SP) and Chloroquine plus Sulphadoxine-Pyrimethamine (CQ + SP). All patients were followed up for 28 days as per WHO (Assessment and Monitoring of Antimalarial Drug Efficacy for the Treatment of Uncomplicated Falciparum Malaria, Geneva, 2003) Protocol. Paired blood samples of treatment failure cases were collected and subjected to MSP 1, MSP 2 and GLURP genotyping for differentiation between re-infection and recrudescence. The data were analysed by Kaplan-Meier survival curve according to WHO standard procedures.

RESULTS

The overall failure rate including both early treatment failure (ETF) and late treatment failure (LTF) of CQ, SP and CQ + SP were 61%, 14% and 8%, respectively, in the study area. Of 60 recurrent malaria cases, genotyping was successful in 49 cases, revealing that most of the (46/49; 94%) cases of recurrent malaria were due to recrudescence.

CONCLUSION

In Jalpaiguri District the overall failure rate of CQ was 61% and of SP 14%, which was well above the WHO recommended cut-off threshold level (10%) for change of drug policy.