Survey of selected viral agents (herpesvirus, adenovirus and hepatitis E virus) in liver and lung samples of cetaceans, Brazil.

Hepatic and pulmonary lesions are common in cetaceans, despite their poorly understood viral etiology. Herpesviruses (HV), adenoviruses (AdV) and hepatitis E virus (HEV) are emerging agents in cetaceans, associated with liver and/or pulmonary damage in mammals. We isolated and molecularly tested DNA for HV and AdV (n = 218 individuals; 187 liver and 108 lung samples) and RNA for HEV (n = 147 animals; 147 liver samples) from six cetacean families. All animals stranded or were bycaught in Brazil between 2001 and 2021. Positive-animals were analyzed by histopathology. Statistical analyses assessed if the prevalence of viral infection could be associated with the variables: species, family, habitat, region, sex, and age group. All samples were negative for AdV and HEV. Overall, 8.7% (19/218) of the cetaceans were HV-positive (4.8% [9/187] liver and 11.1% [12/108] lung), without HV-associated lesions. HV-prevalence was statistically significant higher in Pontoporiidae (19.2%, 10/52) when compared to Delphinidae (4.1%, 5/121), and in southeastern (17.1%, 13/76)-the most industrialized Brazilian region-when compared to the northeastern region (2.4%, 3/126). This study broadens the herpesvirus host range in cetaceans, including its description in pygmy sperm whales (Kogia breviceps) and humpback whales (Megaptera novaeangliae). Further studies must elucidate herpesvirus drivers in cetaceans.

Pathological Findings in Leatherback Sea Turtles (Dermochelys coriacea) During an Unusual Mortality Event in São Paulo, Brazil, in 2016.

The leatherback sea turtle (LST; Dermochelys coriacea) is highly migratory and is primarily distributed throughout tropical and subtropical regions. The LST populations found in Brazil are critically endangered. An unusual mortality event occurred between August and November 2016 with 23 LSTs stranded along a 100 km coastal segment in Iguape, Ilha Comprida and Ilha do Cardoso in southern São Paulo state. This study investigated the pathological findings and most likely causes of death of 10 LSTs. Male (n = 9) and adult (n = 9) animals predominated. All but one animal was in good body condition and all were found dead. The most prevalent gross findings were suggestive of bycatch, namely cutaneous erosions, abrasions and/or lacerations around the neck and flippers (n = 9), generalized congestion (n = 8) and pulmonary oedema (n = 6). Other prevalent gross findings were: cutaneous epibiosis by Stomatolepas elegans (n = 7); ileocecal diverticulitis (n = 7); distal oesophagitis (n = 5); and fibrinous coelomitis (n = 5). Microscopically, the most prevalent findings were: hepatic melanomacrophage centre hypertrophy or hyperplasia (n = 9); interstitial pneumonia (n = 8); multisystemic congestion (n = 6); pulmonary oedema with or without aspirated material (n = 5); adrenal coccidiosis (n = 5) with variable multiorgan involvement; and multiorgan bacterial disease (n = 5). Five animals had food ingesta (cnidarians, crustaceans) in the oesophagus or stomach; only one had evident plastic foreign bodies. Asphyxia due to entanglement in nets was the most frequently identified cause of death (n = 8); a cause of death was not identified in two animals. Our findings provide evidence of the severe negative impact of entanglement in fishing nets in LSTs, raising concerns for conservation. These findings also contribute to knowledge of the pathology of LSTs in South American populations.