[Allelic polymorphism of Plasmodium falciparum MSP-2 gene in blood samples from Gabonese children]

In this study we have undertaken the molecular analysis of the MSP-2 gene of R falciparum isolates collected from schoolchildren living in the village of Dienga (Gabon). Using conventional microscopy and the polymerase chain reaction, 61% of these children harboured parasites without any symptom of malaria (asymptomatic status). Children with a malaria episode were those with an axillary temperature > or = 37.5 degrees C and a parasitaemia > or =800 parasites/microl of blood. Comparisons of the allelic diversity and distribution of MSP-2 gene were carried out according to the clinical status at the time of sampling. Polymorphism of the MSP-2 gene was large in both clinical groups, both asymptomatic and symptomatic (11 identified alleles). The allele FC27/560bp (base pairs) was found significantly in clinical isolates. Prevalence of the 3D7 family was 68% and 44% in asymptomatic infections and clinical infections, respectively. Multiple P. falciparum genotypes were more predominant in clinical cases (2.96 clones/child with a malaria attack vs 2.01 clones/child with asymptomatic infections). We observed also a reduction of the complexity of infection beyond the age of 10 years. These results are discussed in regard to studies conducted in other areas in Africa.