Donna Nook seals
A grey seal swims in muddy water at the Lincolnshire Wildlife Trust's Donna Nook nature reserveDan Kitwood/Getty Images

Marine biologists have discovered that a large number of seal pups living on the Isle of May, are dying from food poisoning.

The poisoning is believed to be caused by a campylobacter bacterial infection caused by raw human sewage.

Professor Samuel Sheppard, who works part of the research team and lectures at Swansea University's College of Medicine, said, "Large numbers of grey seals were infected with bacteria types that are commonly associated with human infection."

"The infected seals also showed symptoms consistent with gastroenteritis that are comparable to those [displayed by] humans." More than half a million people a year in the UK are affected by this illness.

Describing the finding as "striking", Professor Sheppard said he believed it "shows that this important human pathogen may be spreading to vulnerable wildlife species, where its disease potential is unknown."

Dr Ailsa Hall, director of the Sea Mammal Research Unit at the University of St Andrews: "Determining the causes of infection and disease in grey seal pups during the breeding season is critical to our understanding of the factors that affect the early health – and ultimately the survival rates – in these animals."