[Show abstract][Hide abstract] ABSTRACT: Background
Mozambique implemented artemisinin-based combinations therapy (ACT) using artemether-lumefantrine (AL) as the first-line treatment for uncomplicated malaria in 2009. AL remains highly efficacious, but widespread use may soon facilitate emergence of artemisinin tolerance/resistance. The prevalence of pfmdr1 different alleles in Maputo and Mozambique is not known, either after or before the introduction of ACT. Pfmdr1 molecular markers related to Plasmodium falciparum susceptibility were analysed before and after transition to ACT.
A first group of samples was collected between June 2003 and June 2005 and a second group in the period between March 2010 and March 2012. Three alleles were analysed by PCR-RFLP: N86Y, Y184F and D1246Y, in the pfmdr1 gene.
Alleles N86, 184F and D1246 increased from 19.5, 19.6 and 74.4% in 2003–2005 to 73.2, 22.7 and 96.7% in 2010–2012, respectively. After implementation of ACT (2010–2012), pfmdr1 haplotypes, either two- and three-codon basis, were generally less diverse than before the implementation of ACT (2003–2005). The prevalence of haplotypes N86-184Y, N86-D1246 and 184Y-D1246 increased from 12,2, 27.3 and 71.7% in 2003–2005 to 59.4, 84.3 and 78.6% in 2010–2012. The three-codon basis haplotypes NFD and NYD also increased significantly during the same period.
The alleles N86 and 184 F and the triple haplotype N86-184 F-D1246 showed a significantly increased prevalence after introduction of ACT.
[Show abstract][Hide abstract] ABSTRACT: The isolation of bioactive compounds from medicinal plants, based on traditional use or ethnomedical data, is a highly promising potential approach for identifying new and effective antimalarial drug candidates. The purpose of this review was to create a compilation of the phytochemical studies on medicinal plants used to treat malaria in traditional medicine from the Community of Portuguese-Speaking Countries (CPSC): Angola, Brazil, Cape Verde, Guinea-Bissau, Mozambique and São Tomé and Príncipe. In addition, this review aimed to show that there are several medicinal plants popularly used in these countries for which few scientific studies are available. The primary approach compared the antimalarial activity of native species used in each country with its extracts, fractions and isolated substances. In this context, data shown here could be a tool to help researchers from these regions establish a scientific and technical network on the subject for the CPSC where malaria is a public health problem.
No preview · Article · Aug 2011 · Memórias do Instituto Oswaldo Cruz
[Show abstract][Hide abstract] ABSTRACT: Malaria is the major cause of morbidity and mortality in Angola. The most vulnerable groups to Plasmodium falciparum infection are pregnant women and children under five years of age. The use of an intermittent preventive treatment (IPT) with sulphadoxine/pyrimethamine (SP) in pregnant women was introduced in Angola in 2006 by the National Malaria Control Programme, and currently this strategy has been considered to be used for children malaria control. Considering the previous wide use of SP combination in Angola, together to the reported cases of SP treatment failure it is crucial the evaluation of the prevalence of five mutations in pfdhfr and pfdhps genes associated to P. falciparum resistance to SP before the introduction of S/P IPT in children.
The study was conducted in five provinces, with different transmission intensities: Huambo, Cabinda, Uíge, Kwanza Norte, and Malanje. The detection of the mutations in pfdhfr and pfdhps genes was carried out in 452 P. falciparum blood samples by PCR RFLP.
For pfdhfr gene, 90,3% of the samples carried the mutation 51I, with 7.5% of mixed infections; 51% carried wild type allele 59C, with 29.2% mixed infections and; 99.1% of isolates harboured the mutant allele 108N. Concerning, pfdhps gene, 83,1% were mutant type 437G with 11% mixed infections , while 87% of the studied isolates were wild type for codon 540.
This is the first representative epidemiological study of the whole Angola country on the prevalence of the genotypes associated with SP chemoresistance. A high frequency of individual mutations in both genes (51I and 108N in pfdhfr, and 437G in pfdhps) was found, besides a low prevalence of the quintuple mutation.
The data showed that the implementation IPT using SP in children needs to be reviewed.
[Show abstract][Hide abstract] ABSTRACT: Quindolone derivatives, designed to target the malaria parasite digestive vacuole and heme detoxification pathway, have been synthesized by reaction with 2-chloro-N,N-diethylethanamine. This reaction gave N,O-, N,N- and O-alkylated products containing one or two basic side-chains. The compounds were evaluated for antiplasmodial activity against the chloroquine-resistant Plasmodium falciparum W2 strain and for cytotoxicity in HepG2 A16 hepatic cells. By incorporating alkylamine side chains and chlorine atoms in the quindolone nucleus we transformed the inactive tetracyclic parent quindolones into moderate or highly active and selective antimalarial compounds. The most active and selective compound, 5c, showed an IC(50)=51 nM for P. falciparum and a selectivity ratio of 98.
[Show abstract][Hide abstract] ABSTRACT: Malaria is the infectious disease causing the highest morbidity and mortality in Angola and due to widespread chloroquine (CQ) resistance, the country has recently changed its first-line treatment recommendations for uncomplicated malaria, from CQ to artemisinin combination therapies (ACT) in adults, and sulphadoxine/pyrimethamine (S/P) in pregnant women. Loss of SP sensitivity is, however, progressing rapidly in Africa and, in this study, were investigated a number of molecular markers associated to CQ and S/P.
Blood samples were collected from 245 children with uncomplicated malaria, admitted at the Pediatric Hospital Dr. David Bernardino (HPDB), Angola, and the occurrence of mutations in Plasmodium falciparum was investigated in the pfmdr1 (N86Y) and pfcrt (K76T) genes, associated with CQ resistance, as well as in pfdhfr (C59R) and pfdhps (K540E), conferring SP resistance.
The frequencies of pfmdr1 mutations in codon 86 were 28.6% N, 61.3% Y and 10.1% mixed infections (NY). The frequency of pfcrt mutations in codon 76 were 93.9% K, 5.7% T and 0.4% mixed infections (KT). For pfdhfr the results were in codon 59, 60.6% C, 20.6% R and 18.8% mixed infections (CR). Concerning pfdhps, 6.3% of the isolates were bearers of the mutation 540E and 5.4% mixed infections (K540E).
The results of this epidemiologic study showed high presence of CQ resistance markers while for SP a much lower prevalence was detected for the markers under study.
[Show abstract][Hide abstract] ABSTRACT: Plasmodium falciparum is the predominant human malaria species in Mozambique and a lead cause of mortality among children and pregnant women nationwide. Sulphadoxine/pyrimethamine (S/P) is used as first line antimalarial treatment as a partner drug in combination with artesunate.
A total of 92 P. falciparum-infected blood samples, from children with uncomplicated malaria attending the Centro de Saude de Bagamoyo in the Province of Maputo-Mozambique, were screened for S/P resistance-conferring mutations in the pfdhfr and pfdhps genes using a nested mutation-specific polymerase chain reaction and restriction digestion (PCR-RFLP). The panel of genetic polymorphisms analysed included the pfdhfr 164L mutation, previously reported to be absent or rare in Africa.
The frequency of the S/P resistance-associated pfdhfr triple mutants (51I/59R/108N) and of pfdhfr/pfdhps quintuple mutants (51I/59R/108N + 437G/540E) was 93% and 47%, respectively. However, no pfdhfr 164L mutants were detected.
The observation that a considerably high percentage of P. falciparum parasites contained S/P resistance-associated mutations raises concerns about the validity of this drug as first-choice treatment in Mozambique. On the other hand, no pfdhfr 164L mutant was disclosed, corroborating the view that that this allele is still rare in Africa.