Dolphins became more often ill with a stomach ulcer due to parasitic worms. Scientists believe that the increase in the detection of open ulcers may be due to both an increase in the parasite population and a deterioration in the habitat, which has made cetaceans more vulnerable. This is stated in a study by scientists from the University of Valencia, published in the journal Journal of Helminthology.

Gastric ulcers in cetaceans are provoked by Anisakis worms and parasites closely related to them. They enter the animal’s stomach with food, and then attach to its walls and multiply. In some cases, their activity leads to the death of the animal.

Parasites of the genus Anisakis are also dangerous for humans – even dead larvae of worms can cause an allergic reaction, and sexually mature individuals are able to make holes in the walls of the gastrointestinal tract.

In order to better understand their danger to humans, the researchers studied their effect on cetaceans – in particular, on dolphins that live near the Atlantic coast of Spain. The work showed that the number of cases of gastric ulcers among mammals in this region in 2017–2018 significantly increased compared with 1991–1996.

On the one hand, scientists believe that the increase in the number of peptic ulcer cases among dolphins has caused an increase in the population of Anisakis worms, but this cannot be unequivocally stated, more research is needed.

On the other hand, the cause may be the greater susceptibility of dolphins to changes in habitat, the authors of the study write.