A thirteen-year analysis of Plasmodium falciparum populations reveals high conservation of the mutant pfcrt haplotype despite the withdrawal of chloroquine from national treatment guidelines in Gabon.

BACKGROUND: Chloroquine resistance (CR) decreased after the removal of chloroquine from national treatment guidelines in Malawi, Kenia and Tanzania. In this investigation the prevalence of the chloroquine resistance (CQR) conferring mutant pfcrt allele and its associated chromosomal haplotype were determined before and after the change in Gabonese national treatment guidelines from chloroquine (CQ) to artesunate plus amodiaquine (AQ) in 2003. METHODS: The prevalence of the wild type pfcrt allele was assessed in 144 isolates from the years 2005 - 07 by PCR fragment restriction digest and direct sequencing. For haplotype analysis of the chromosomal regions flanking the pfcrt locus, microsatellite analysis was done on a total of 145 isolates obtained in 1995/96 (43 isolates), 2002 (47 isolates) and 2005 - 07 (55 isolates). RESULTS: The prevalence of the mutant pfcrt allele decreased from 100% in the years 1995/96 and 2002 to 97% in 2005 - 07. Haplotype analysis showed that in 1995/96 79% of the isolates carried the same microsatellite alleles in a chromosomal fragment spanning 39 kb surrounding the pfcrt locus. In 2002 and 2005 - 07 the prevalence of this haplotype was 62% and 58%, respectively. Pfcrt haplotype analysis showed that all wild type alleles were CVMNK. CONCLUSION: Four years after the withdrawal of CQ from national treatment guidelines the prevalence of the mutant pfcrt allele remains at 97%. The data suggest that the combination of artesunate plus AQ may result in continued selection for the mutant pfcrt haplotype even after discontinuance of CQ usage.

The use of paediatric artemisinin combinations in sub-Saharan Africa: a snapshot questionnaire survey of health care personnel.

BACKGROUND: Paediatric drug formulations for artemisinin combination therapy (P-ACT) have been developed over the past few years and have been shown to improve the therapeutic management of young children with uncomplicated falciparum malaria. This process was however not equally paralleled by a timely adoption of P-ACT in national and international treatment recommendations. National malaria programmes in sub-Saharan Africa have not yet widely embraced this new therapeutic tool. To which extent P-ACT is used in the field in sub-Saharan Africa is not known to date. METHODS: This snapshot questionnaire survey aimed to provide an overview on the current routine practices for the availability and use of P-ACT as anti-malarial treatment for young children in sub-Saharan Africa. Health care personnel in seven countries in West-, Central, and East-Africa were invited to answer a structured questionnaire assessing use and availability of P-ACT. RESULTS: A total of 71 respondents including doctors, nurses and pharmacy personnel responsible for the anti-malarial treatment of young children were interviewed. P-ACT was used by 83% (95% confidence interval: 73-90%; n = 59) as first-line treatment for young children. Use of 15 different P-ACT products was reported among which only two have received WHO prequalification status and approval by a stringent registration authority. Use of a specific P-ACT product was not linked to consumer prices or availability of supporting clinical trial data, but may depend more on the marketing capacity of the manufacturer. Major differences in frequency and dosing of anti-malarial regimens with identical anti-malarial compounds and the marketing of loose combinations were recorded. CONCLUSION: Paediatric ACT is widely used for the treatment of uncomplicated malaria in young children. However, the majority of P-ACT formulations in use do not meet highest international quality standards evoking concerns for patients' safety and the induction of drug resistance. Improving the quality of currently marketed P-ACT should constitute a public health priority besides their adoption into official treatment recommendations.