RESUMO
The aim of the present study was to determine the genetic diversity and allelic frequencies of the genes encoding for the merozoite surface protein-1 (MSP-1) and protein-2 (MSP-2) of P. falciparum collected from Beninese patients during the high and low transmission seasons in Cotonou, in South Benin. Sixty and twenty-four patients were sampled during the dry and wet seasons, respectively Parasite DNA was analysed using allele-specific primers to amplify block2 of MSP-1 and central variable region of MSP-2. A total of 12 (K1, Mad20, Ro33) MSP-1 and 23 (3D7, FC27 and hybrids) MSP-2 alleles were detected. Neither age nor transmission season modified the genetic diversity of P. falciparum nor the distribution of MSP-1 and MSP-2 alleles. Combining the results of MSP-1 and MSP-2 genotyping, multiple P. falciparum infections were observed in 57% and 70% of isolates during the wet and dry seasons, respectively. The complexity of infections defined as the number of parasite genotype per isolate was 2.4 and it was not affected either by the season or by the age of the host. We conclude that change of season did not influence the permanent turn-over of parasites and the complexity of infections. Data obtained here will serve as a baseline for future studies, such as the impact of malaria control measures on parasite populations, to be conducted in Cotonou.
Assuntos
Antígenos de Protozoários/genética , Variação Genética , Malária Falciparum/transmissão , Proteína 1 de Superfície de Merozoito/genética , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Estações do Ano , Adolescente , Adulto , Fatores Etários , Animais , Benin , Criança , HumanosRESUMO
In field-based studies, sometimes it is difficult to collect and store samples. We have evaluated a method of malaria parasite deoxyribonucleic (DNA) extraction from non-stained thick dried blood smears collected from 108 Gabonese patients. This method of DNA isolation was compared to those using phenol/chloroform. Patients parasitemia ranged from 0 to 240,000 parasites/microliter of blood. Both methods of DNA preparation gave similar results. Of the 108 slides, 57% were Plasmodium falciparum positive after PCR analysis of the MSA-2 gene and 34% were positive by microscopical examination. Thirty-six and seventy-two blood smears from patients were also tested after one and four weeks' storage respectively, at room temperature, and the parasite DNA was successfully extracted. We conclude that this simple method of collection and rapid procedure of parasite DNA isolation are adequate and convenient in the field when a large number of samples are required and in the case of repetitive samplings of patients.