Ultra-structural characterization of Diplostomum sp metacercarian in Orestias luteus from Lake Titicaca, Peru

Abstract

The objective of the present work was the ultra-structural characterization of metacercariae of Diplostomum sp in Orestias luteus from Lake Titicaca, Puno, Peru. 35 fish collected through non-probabilistic sampling were anesthetized with tricaine monosulfonate (Tricaine-s®) and necropsied to determine the number of Diplostomum sp. present per fish. The extracted parasites were fixed and preserved for study by scanning electron microscope. The frequency of parasitosis was 48.6% (IC 95%: 32.0-65.1) with a mean parasitic intensity of infection of 3.53 (low). The metacercaria of Diplostomum sp. are lingui form in shape with papillae unevenly distributed on the surface of the body, have a posterior border with a slight conical prominence, and an extreme anterior circle where the oral suction cup is located. There is also an ellipsoidal acetabulum located in the anterior and ventral third of the posterior segment of the body; behind that is the ovoid-shaped tri bocytic organ. The morpho anatomic characteristics of the parasite under study coincide with Diplostomum mordax. The prevalence of Diplostomum sp in Lake Titicaca is high compared to previous years. However, the average intensity is low; suggesting that, for the moment, Diplostomum sp. is not a threat to the health of O. luteus.