Infection dynamics of sp. (Digenea: Diplostomidae) in first and second intermediate hosts from an Andean Patagonian lake (Argentina)

Abstract

In Argentinean Patagonia, a species of the genus Posthodiplostomum has been reported infectingpopulations of the snail Anisancylus obliquus and the galaxiid fi sh Galaxias maculatus (small puyen), meanwhileadults would develop in piscivorous birds. The aim of the present work was to describe the seasonal dynamicsof this parasite in the intermediate hosts inhabiting a small, shallow Patagonian Andean lake. Samples ofsnails and fi sh from Patagua Lake (40° 46? S - 71º 36? W) were collected monthly from October 2010 to March2011. The larval infection of Posthodiplostomum sp. increases in spring. Snails were infected from Novemberto January, with the highest prevalence in December (8.2%), decreasing in January (3.1%). In fi sh, prevalenceranged between 70% (November) and 100% (December to March). The highest infection values were recordedin larger fi sh, while the small fi sh with sizes less than 40 mm exhibited low infection levels. So, we can infer thatthe life cycle of Posthodiplostomum sp. in Patagonia shows a seasonal pattern, with larval development duringspring, when cercariae emerge from larger snails, resulting in a higher prevalence of fi sh in the littoral.