Abstract
We report the results of pathological, immunohistochemical and molecular genotyping analyses in a Bryde's whale (Balaenoptera edeni) with disseminated toxoplasmosis. A 10.7 m-long, adult, male Bryde's whale in poor body condition stranded alive in August 21st, 2018, in ‘Pontal do Ipiranga’, Linhares, Espirito Santo state (Brazil). The animal died shortly after stranding and was promptly autopsied. The main gross findings were: diffuse axial skeletal muscle atrophy; generalized congestion, petechiation and ecchymoses; necrotizing splenitis, hepatitis, myocarditis, pneumonia and lymphadenitis (prescapular, pulmonary, mediastinal, mesenteric); bilateral scapulohumeral hemarthros; and severe pulmonary edema. Microscopic examination confirmed the aforementioned diagnoses, featuring a histopathologic signature characterized by multisystemic necrotizing inflammation with vasculitis and disseminated intravascular coagulation, thrombosis and numerous intralesional protozoal cysts and extracellular tachyzoites morphologically compatible with Toxoplasma gondii. Immunohistochemical and polymerase chain reaction (PCR) analysis targeting a repetitive 529 bp DNA fragment of T. gondii confirmed toxoplasmosis in the liver, spleen, lung and lymph nodes. PCR-restriction fragment length polymorphism (RFLP) analysis using 11 markers identified a new non-archetypal genotype, ToxoDB-RFLP genotype #300. Further, the genotyping by microsatellite technique employed 15 markers and confirmed a unique non-archetypal T. gondii strain, designated PS-TgBaledBrES1. These novel results add to the diversity of this parasite in the world and to the scarce data on T. gondii genotype distribution in cetaceans, represent the first record of toxoplasmosis in a Bryde's whale and set the baseline knowledge for future research on T. gondii genotyping research in marine mammals from South America.
Highlights
Toxoplasma gondii, an intracellular protozoan parasite responsible for toxoplasmosis, affects a wide number of hosts including non-human animals and humans with varying morbidity and mortality (Howe and Sibley, 1995; Dubey, 2010; Calero-Bernal and Gennari, 2019)
The first record of toxoplasmosis in cetaceans was in a Guiana dolphin (Sotalia guianensis) from Rio de Janeiro state, Brazil, in the 1970s (Bandoli and Oliveira, 1977)
Given the relatively limited knowledge on T. gondii genotype distribution among marine mammals worldwide and in Brazil, as well as the elusive potential epidemiological associations with public health and terrestrial T. gondii epidemiology, this study aimed at reporting the results of pathological, immunohistochemical, and molecular genotyping analyses in a Bryde’s whale with disseminated toxoplasmosis
Summary
Toxoplasma gondii (phylum Apicomplexa), an intracellular protozoan parasite responsible for toxoplasmosis, affects a wide number of hosts including non-human animals and humans with varying morbidity and mortality (Howe and Sibley, 1995; Dubey, 2010; Calero-Bernal and Gennari, 2019). Notwithstanding, T. gondii is known to cause sporadic clinical disease and fatality in marine mammals in many geographic areas. It is considered emergent in certain locations, such as the Arctic (Donahoe et al, 2014). The first record of toxoplasmosis in cetaceans was in a Guiana dolphin (Sotalia guianensis) from Rio de Janeiro state, Brazil, in the 1970s (Bandoli and Oliveira, 1977). Knowledge on the exposure and the infection of this protozoan has been gained primarily by serological, pathological, and molecular techniques in a wide variety of captive and freeranging cetaceans worldwide (Inskeep et al, 1990; Omata et al, 2006; Mazzariol et al, 2012; Gonzales-Viera et al, 2013; CostaSilva et al, 2019)
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