Lesions Associated withHalocercus brasiliensisLins de Almeida, 1933 in the Lungs of Dolphins Stranded in the Northeast of Brazil

Abstract

The parasitic fauna of cetaceans is an important tool for ecological studies, including analyses on the causes of death. Halocercus brasiliensis is a nematode frequently found in the bronchi and bronchioles of some cetaceans, and it is commonly associated with focal inflammation of the respiratory tract leading to bacterial pneumonia and septicemia and, sometimes, to death. The objective of this study was to report infections by H. brasiliensis in the respiratory tract of Delphinidae stranded on the northern seaside of Bahia, Sergipe, and south of Alagoas, all states in the northeast region of Brazil. A total of 30 individuals, 1 Feresa attenuate (pygmy killer whale), 9 Stenella clymene (Clymene dolphin), and 20 Sotalia guianensis (Guiana dolphin) were studied. In 16 of them, the presence of H. brasiliensis was observed with a mean intensity of 3.5 ± 0.6 (range 1-9) in the hosts. Macroscopically, parasitic calcified nodules, lung congestion, edema, and emphysema were observed. Histopathological examination showed interstitial and granulomatous pneumonia with multifocal infiltrates, discrete to moderate edema, congestion, diffuse hemorrhage, and foci of calcification. We conclude that parasitic pneumonia in the sampled individuals may have directly contributed to stranding and death of the animals.

The Pathology of Cetacean Morbillivirus Infection and Comorbidities in Guiana Dolphins During an Unusual Mortality Event (Brazil, 2017–2018)

“…The host and geographic range for this nematode is not fully known; however, it affects multiple cetacean species with variable pathogenicity. 34,52 Other extrapulmonary gross findings observed in Guiana dolphins, such as cavitary effusion, icterus, hepatic lipidosis, lymphadenomegaly, and gastrointestinal parasitosis, have been described in epizootic DMV-infected striped dolphins. 22,23 Exacerbated parasitism may be linked to DMV infection.…”

Assessing Disease and Mortality among Small Cetaceans Stranded at a World Heritage Site in Southern Brazil

“…This parasite affects the lower respiratory tract of several cetaceans [ 32 , 46 , 47 ] and associated infestations have been related to severe manifestations of dyspnea, moderate-to-severe pneumonia and death in S . guianensis and other cetaceans throughout Brazil [ 34 , 48 , 49 ]. Pulmonary nematode infestations were characterized by lesions that varied from interstitial pneumonia (in larval migration) to chronic bronchitis, caused by intrabronchial and/or intrabronchiolar adult lung worms [ 50 ].…”

Bacteriological and histopathological findings in cetaceans that stranded in the Philippines from 2017 to 2018

“…Parasites in cetaceans may predispose these animals to bacterial infections, cardiovascular complications, septicemia and other conditions, which are also frequently reported as probable causes of death during their stranding events [16,[52][53]. Until this study, there was no histopathological evidence of coccidian cysts such as T. gondii and Sarcocystis sp.…”

“…On the other hand, histopathological assessments proved to be useful in determining probable causes of death or debility of stranded cetaceans worldwide [13][14][15][16][17]. Tissue lesions help confirm parasitic and bacterial infections, co-morbidities, physical injuries (e.g., brought about by fisheries or human interactions) and bioaccumulation of chemical compounds (e.g., persistent organic pollutants) in cetaceans [16,[18][19][20][21][22]. Histopathological assessment is a practical and informative tool that provides pathological evidence and reinforce the necropsy being done in dead cetaceans as part of the stranding response.…”