They detect for the first time the death of dolphins by a bacterium that also makes humans sick

Spanish scientists discovered that five dolphins found dead on the Atlantic and Mediterranean coasts of Spain had infections caused by two bacteria, one of which causes human disease and had never been detected in these mammals until now. Experts assured that the deaths occurred due to pathogens.

The research was conducted by specialists from the University Institute of Animal Health and Food Safety (IUSA) of the University of Las Palmas de Gran Canaria (ULPGC) and members of the Complutense University of Madrid (UCM) participated.

The studies were carried out in four listed dolphins (Stenella coerulealba) and one of the mules, better known as bottlenose (Tursiops truncatus). Three of the listed dolphins were found stranded on the coasts of Almeria, Cadiz, and Malaga; the fourth in Fuerteventura and the bottlenose dolphin in Gran Canaria, reported the Veterinary Journal of Spain.

“All animals had suppurative pyogranulomatous and thromboembolic lesions in two or more organs. The microbiological analyses we carried out allowed the identification of two bacterial pathogens included in the genus Nocardia: Nocardia otitidiscaviarum and Nocardia farcinica,” said Ana Isabel Vela, professor of Animal Health at the UCM Faculty of Veterinary Medicine.

The first, Nocardia otitidiscaviarum, is a microorganism that causes systemic, skin and lung infections in humans, especially in people with immunocompromised diseases and has not been detected as causing diseases in cetaceans until now.

The other bacterium, Nocardia farcinica, had been found in other marine species, also cetaceans, but Spanish experts found it for the first time in dolphins in the wild.

Scientists are concerned about the stranding of animals in things, sometimes alive and sometimes dead. Deaths of marine fauna occur due to natural reasons, due to the action of humans or due to pathologies such as the case of the five dolphins studied.

“There is a lack of knowledge of the diseases that affect this type of animal for two reasons: the wide diversity of aquatic species and how complex it is to investigate pathologies in free-living animals,” Vela explained.

The ULPGC team of experts, led by Antonio Fernández, is the reference centre of the OIE (International Organization for Animal Health) in Spain in relation to these species and collaborates with the UCM in microbiological research, led by Vela.

These scientific groups provide “valuable data and help to understand the causes of death related to pathogens, some zoonotics, in these marine animals”, including, therefore, the multidisciplinary vision of One Health, said the specialists who did the study.

Dolphins are intelligent mammals, capable of even catching whales. “They are not fish, they are mammals that communicate with each other in a wonderful language, typical of each community as if it were a dialect,” said Dr. Juan Enrique Romero.

“Dolphins help disabled children, dolphins bond with us, take people out, save people in danger,” he added.

But global warming, indiscriminate fishing and plastic pollution, among other factors, are having a dramatic impact on different marine species. One of them is the Franciscan dolphin (Pontoporia blainvillei), which is the cetacean most affected by human actions in the South Atlantic. This little dolphin, which made headlines a few years ago due to the regrettable decision of some tourists to remove it from the seashore to take a selfie, is distributed from Itaúnas, Espírito Santo Province, Brazil, to the New Gulf, Chubut Province, Argentina.

One of the possible reasons why this marine mammal is particularly exposed is that it is a cetacean that lives only in coastal waters that do not exceed 30 or 35 meters deep. This exposes it both to the threat of by-catch, as well as to chemical and noise pollution. A study by the Research Group on Biology, Ecology and Conservation of Marine Mammals at the National University of Mar del Plata, also showed that 30% of the animals of this species analyzed, stranded or killed by bycatch in the Buenos Aires region, had ingested marine litter.

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