Abstract
BackgroundIn Benin, the National Malaria Control Programme (NMCP) changed the policy of malaria treatment in 2004 following increasing of failure rate of treatment with chloroquine (CQ) and sulphadoxine-pyrimethamine (SP). The objective of this study was to determinate the prevalence of Plasmodium falciparum molecular markers that are associated with resistance to CQ and SP in Benin seven years after the new policy was instituted.MethodsThe study was conducted in southern Benin, a region characterized by a perennial malaria transmission. Blood samples were collected in 2011 from children presenting with symptomatic and asymptomatic P. falciparum infections and living in the same area. The prevalence of critical point mutations in the genes of pfcrt (codon 76), pfmdr1 (codon 86), pfdhfr (codons, 51, 59 and 108) and pfdhps (codons 437, 540) was examined in parasite isolates by mutation-specific restriction enzyme digestion of nested PCR products.ResultsA high prevalence of parasites carrying point mutations in all studied targets was found: T76: 93.9% [89.8; 96.7], I51: 96.2% [92.7; 98.4], R59: 93, 9% [89.7; 96.7], N108: 97.6% [94.6; 99.2] and G437: 71.4% [64.8; 77.4]. No mutation was found at codon 540 of the pfdhps gene. The proportion of parasite isolates carrying triple mutation in the pfdhfr gene IRN (I51, R59 andN108) and quadruple mutation on the combination of pfdhfr/pfdhps IRNG (I51, R59, N108 and G437) was 91.5% [86.9; 94.9] and 65.7% [58.9; 72.1], respectively. Analysis of mutation in relation to the clinical status (symptomatic or asymptomatic) and according to age (younger or older than 10 years) showed similar very high frequencies in each category without significant difference between two groups.ConclusionsThese results suggest a persistence level of resistance of P. falciparum to CQ and SP, seven years after the recommendation of the change of malaria treatment policy in Benin. The distribution of mutations studied was neither related to age nor to clinical status.
Highlights
In Benin, the National Malaria Control Programme (NMCP) changed the policy of malaria treatment in 2004 following increasing of failure rate of treatment with chloroquine (CQ) and sulphadoxine-pyrimethamine (SP)
The main objective of this study was to determine the prevalence of P. falciparum molecular markers that are associated with resistance to CQ and SP by analysing the point mutations in pfcrt, pfmdr1, pfdhfr and pfdhps gene using samples from asymptomatic children and those with uncomplicated malaria in southern Benin
Characteristics of the study population A total of 2,249 asymptomatic children were screened for malaria parasitaemia; 208 samples were found positive for P. falciparum and were collected and stored as spots on filter paper
Summary
In Benin, the National Malaria Control Programme (NMCP) changed the policy of malaria treatment in 2004 following increasing of failure rate of treatment with chloroquine (CQ) and sulphadoxine-pyrimethamine (SP). In vivo efficacy studies, conducted in 2002 by the National Malaria Control Programme (NMCP) according to the WHO protocol, had revealed treatment failures rates by region ranging from 15.0–61.3% with CQ and 3.3–45.9% with SP in under-fives followed up to 14 days [1] These studies were performed in five regions of the country located in the south (Lokossa), centre (Dassa Zoume, Abomey) and north (Kouandé, Malanville), with an overall failure rate of 35.2 for CQ (11.5% and 23.7% early and late treatment failures respectively) and 22.8% for SP (8.3% and 24.5% early and late treatment failures respectively) In Benin, no data on the prevalence of parasite molecular markers of resistance was available before the treatment policy change and only a limited number of studies of molecular markers of anti-malarial drug resistance in P. falciparum have been carried out [12,13] These studies have focused on genes pfdhfr and pfdhps and reported high proportion of quadruple mutant parasites (above 80%). The main objective of this study was to determine the prevalence of P. falciparum molecular markers that are associated with resistance to CQ and SP by analysing the point mutations in pfcrt, pfmdr, pfdhfr and pfdhps gene using samples from asymptomatic children and those with uncomplicated malaria in southern Benin
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