Molecular identification of Mycobacterium Bovis in a Franciscana (Pontoporia Blainvillei) in Patagonia, Argentina

Abstract

The franciscana (Pontoporia blainvillei) is a small cetacean endemic to the southwestern Atlantic Ocean in a vulnerable conservation status. Their habitat is restricted to shallow waters and estuaries. In 2020, fresh female carcass of franciscana (juvenile/subadult) was found dead alone (individual stranding) on a public access beach in the Rio Negro Estuary in “Balneario El Cóndor”, Argentinian Patagonia. Grossly, a widespread granulomatous lesion compatible with tuberculosis were observed. A sample of mesenteric lymph nodes with granulomatous lesions (~50 g) was collected for bacteriological culture and molecular identification. Bacterial growth was observed in Stonebrink media and Ziehl Neelsen staining revealed acid-fast bacilli. Identification of a Mycobacterium bovis strain with the SB0288 spoligotype was obtained. The spoligotype detected here has already been reported in cattle and humans. Presumably, fluids and feces of infected livestock and wild animals, or their carcasses, may contaminate the water. Thus, this report demonstrates the potential risk of zoonotic tuberculosis transmission through wastewater. Contaminated wastewater is eventually a threat to animal species living in the area, and potentially becomes a zoonotic risk.