Therapeutic efficacy of chloroquine and sequence variation in pfcrt gene among patients with falciparum malaria in central India.
OBJECTIVE
To assess the therapeutic efficacy of chloroquine (CQ) treatment against uncomplicated Plasmodium falciparum infections in a tribal population of central India (Madhya Pradesh) and to investigate the prevalence of mutant P. falciparum chloroquine-resistant transporter (pfcrt) gene in the parasite population.


METHODS
Clinical and parasitological response was determined by in-vivo testing. For molecular testing, the parasite DNA was extracted from blood samples and used to amplify and sequence parts of the pfcrt (44-177 codons), MSP1 (block 2) and MSP2 (central repeat region) genes.


RESULTS
Of 463 patients presenting fever, 137 tested positive for P. falciparum. They were treated with CQ. Of these, 58% participated in the study. Overall, treatment failure occurred in 53% of participants. Children under 5 years of age showed significantly more CQ resistance than adults. Mutant genotype S(72)V(73)M(74)N(75)T(76) was prevalent among both CQ responders (61.29%) and non-responders (66.7%). Interestingly, several patients from the CQ non-responder group (33.3%, n = 39) were harbouring parasite with wild type C(72)V(73)M(74)N(75)K(76) genotype of the pfcrt gene. Microsatellite sequences downstream of exon 2 varied widely among both wild type and mutant pfcrt haplotypes.


CONCLUSIONS
The high rate of treatment failure in the present study clearly indicates the need to reassess the use of CQ as first-line antimalarial therapy in central India. This is supported by the presence of mutant pfcrt genotype among majority of the parasite population of the CQ non-responder group of patients. However, the presence of wild type amino acid at codon 76 of the pfcrt gene among several patients with CQ non-responders requires further investigations.
Bharti
Praveen Kumar
PK
Regional Medical Research Centre for Tribals, Jabalpur, India.
Alam
Mohammad Tauqeer
MT
Boxer
Robert
R
Shukla
Man Mohan
MM
Gautam
Sant P
SP
Sharma
Yagya D
YD
Singh
Neeru
N
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics; D000962:Antimalarials / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002738:Chloroquine / Q000627:therapeutic use*; D004252:DNA Mutational Analysis / Q000379:methods; D016054:DNA, Protozoan / Q000235:genetics; D004351:Drug Resistance / Q000235:genetics; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics*; D020066:Merozoite Surface Protein 1 / Q000235:genetics; D008875:Middle Aged; D009154:Mutation; D010963:Plasmodium falciparum / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods; D015800:Protozoan Proteins / Q000235:genetics*; D017211:Treatment Failure; D055815:Young Adult
D000953:Antigens, Protozoan; D000962:Antimalarials; D016054:DNA, Protozoan; D026901:Membrane Transport Proteins; D020066:Merozoite Surface Protein 1; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium; D002738:Chloroquine