Volume 87, Issue 5
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Rapid urbanization in Brazil has meant that many persons from rural areas where 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 apart 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.


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  • Received : 13 Oct 2011
  • Accepted : 29 Jul 2012
  • Published online : 07 Nov 2012

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