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Haematological and histopathological analysis in South American fish Piaractus mesopotamicus parasitized by monogenean (Dactylogyridae)

Brazilian Journal of Biology. 74(4):1000-1006 DOI 10.1590/1519-6984.09513


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Journal Title: Brazilian Journal of Biology

ISSN: 1519-6984 (Print); 1678-4375 (Online)

Publisher: Instituto Internacional de Ecologia

Society/Institution: Sociedade de Biologia do Brasil

LCC Subject Category: Science: Biology (General) | Science: Zoology | Science: Botany

Country of publisher: Brazil

Language of fulltext: English

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GT Jerônimo

SB Pádua

D Bampi

ELT Gonçalves

P Garcia

MM Ishikawa

ML Martins


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Time From Submission to Publication: 5 weeks


Abstract | Full Text

Monogeneans are the parasites mostly found on the body surface and gills of fish and can cause large losses in farmed fish. Some studies demonstrate elevated parasitic levels causing hematological alterations. But few of them relate the effects of parasitism on the hematology and histopathology of native freshwater farmed fish. This study evaluated the host-parasite relationship in pacu (Piaractus mesopotamicus) parasitized by the monogenean Anacanthorus penilabiatus. Hematological and parasitological assessments were obtained in 60 fish captured in a fish farm located in Dourados, State of Mato Grosso do Sul, Central Brazil. Fish were analyzed in different categories of parasite number: class I (n=13; 0-200 parasites), class II (n=17; 201-1200 parasites); class III (n=7; 1201-2200 parasites); and class IV (n=23; more than 2200 parasites per host). The highest levels of parasitism caused significant decrease (p<0.05) in the hematocrit, red blood cells (RBC), mean hemoglobin concentration (MCHC) and basophils number. Thrombocytes, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), monocytes, eosinophils, neutrophils and LG-PAS did not present significant difference among the parasitic levels. In contrast, increased number of total leukocytes and lymphocytes were found in highly-parasitized fish. A positive linear correlation (p<0.01) was found between the amount of parasites and fish weight. Histopathology revealed severe hyperplasia, sub-epithelial edema, fusion of the secondary lamellae, focal and multifocal necrosis in highly parasitized fish.