Genotyping natural infections of Schistosoma mansoni in Biomphalaria alexandrina from Damietta, Egypt, with comparisons to natural snail infections from Kenya.

a Parasitology Department, Medical Research Institute, Alexandria University, 165 EI-Horreya Avenue, Alexandria, Egypt, PO Box 21561.
Journal of Parasitology (Impact Factor: 1.32). 02/2011; 97(1):156-9. DOI: 10.1645/GE-2537.1
Source: PubMed

ABSTRACT The distribution of Schistosoma genotypes among individuals in snail populations provides insights regarding the dynamics of transmission and compatibility between schistosome and snail hosts. A survey of Biomphalaria alexandrina from Damietta (Nile Delta, Egypt), an area subjected to persistent schistosomiasis control efforts, provided only 17 snails infected with Schistosoma mansoni (6.1% overall prevalence), each shown by microsatellite analysis to have a single genotype infection. By contrast, recent studies of uncontrolled S. mansoni transmission foci in Kenya revealed that 4.3% Biomphalaria pfeifferi and 20-25% Biomphalaria sudanica snails had multiple genotype infections. Compared with the 3 Kenyan populations, the Egyptian population of S. mansoni also showed a lesser degree of genetic variability and was genetically differentiated from them. We suggest that tracking of genotype diversity in infected snails could be further developed to serve as an additional and valuable independent indicator of efficacy of schistosomiasis control in Egypt and elsewhere.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Rapid urbanization in Brazil has meant that many persons from rural areas to which Schistosoma mansoni is endemic have migrated to cities. Discovery of a focus of active transmission in the city of Salvador prompted a citywide survey for active and potential transmission sites. Cercariae shed from infected snails collected from four locations were used to determine how these samples were related and if they were representative of the parasite population infecting humans. Each cercarial collection was greatly differentiated from the others, and diversity was significantly lower when compared with eggs from natural human infections in one site. Egg samples collected 7 years earlier in one neighborhood showed little differentiation (Jost's D = 0.01-0.03). Given the clonal nature of parasite reproduction in the snail host and the short-term acquisition of parasites, cercariae from collections at one time point are unlikely to be representative of the diversity in the human population.
    The American journal of tropical medicine and hygiene 09/2012; · 2.53 Impact Factor


Available from
May 21, 2014