Hematologic variables of free-living Leptodactylus luctator with and without hemoparasites and thrombidiform mites in southern Brazil.

Abstract

It has been suggested that anuran amphibian parasites can cause clinical signs in situations of environmental imbalance. In the family Leptodactylidae, information about hematology is scarce, although these are well-known tools for the diagnosis and prognosis in clinical practice and potential bioindicators of environmental stress. The objective of this study is to describe Leptodactylus luctator hematology, to report the occurrence of hemoparasites and thrombidiform mites, and to compare the hematological variables under the presence and absence of these organisms. Ectoparasites and heparinized blood samples from 40 free-living specimens of L. luctator were collected for analysis. Hematologic variables and total plasma protein were compared between groups with and without hemoparasites and intradermal mites. As results, structures compatible with hemogregarines, Lankesterella sp., five morphotypes of Trypanosoma spp., microfilaria, Aegyptianella sp., an unidentified intraleukocytic hemoparasite, and frog erythrocytic virus (FEV) inclusion bodies were identified in the blood samples, besides Hannemania spp. intradermal mites. The hemoparasite occurrence was higher than previously reported in other anuran families and locations. Also, L. luctator has smaller red blood cells (RBCs) and white blood cells (WBCs), and a hyposegmentation of the neutrophil nucleus, when compared to many other amphibians. White blood cell, neutrophil, and monocyte counts were higher in animals parasitized by mites. There was no correlation between the number of parasitized RBCs and hematologic variables. This study provides anuran hematologic information, in addition to indicating a host reaction to infestation by Hannemania spp. mites, besides constituting the first record of the distribution of hemoparasites and intradermal mites in L. luctator of the study region.