Return of North Sea virus that killed half of UK's seals

A virus that wiped out half of Britain's seal population 14 years ago has returned and is likely to lead to a second devastating epidemic.

Tests on dead seals washed up in Lincolnshire and Norfolk have confirmed the worst fears of conservationists, who are bracing themselves for thousands of deaths over the coming weeks.

An outbreak of phocine distemper virus (PDV) in the North Sea has already killed 2,500 seals in Sweden, Denmark, the Netherlands and France.

In 1988, PDV killed some 18,000 animals throughout Europe, including 60 per cent of Britain's harbour seal population and about a third of common seals.

Professor John Harwood, from the sea mammals research unit at the University of St Andrews, said: "It is a matter of holding our breath but there are likely to be thousands of victims.

"It is possible that after the 1988 epidemic there may a degree of resistance in the population, but it is a virus that progresses very rapidly. We will know the scale of the fatalities very quickly."

The virus, which attacks the immune system and leaves animals susceptible to pneumonia, is spread by seals coughing and sneezing in communal colonies on sandbanks and beaches. It can kill a seal within 10 days of infection and there is no known cure.

It is likely to have reached British animals when they came into contact with infected seals from Scandinavia or the Netherlands. Adult seals can swim hundreds of miles in a day.

The British outbreak was confirmed by the RSPCA after five dead seals, including three pups, were found around the Wash, which has some of the largest seal colonies in Britain.

A spokesman said: "The animals were found two weeks ago but the tests take a long time to confirm the virus. It is likely to have spread further since then."

Although the virus is not harmful to humans, holidaymakers were being warned not to touch or approach sick or dead seals and instead report ailing animals to the RSPCA and other rescue groups.

The population of harbour and common seals had been returning to pre-1988 levels this year, prompting hopes that the virus had disappeared.

PDV reappeared in May in seals off the Danish island of Anholt. They might have been infected by harp seals from the Arctic, which are known carriers, but there have been no sightings of the species in the North Sea this year.

Another theory put forward by Scandinavian scientists is that mink, which can also carry the virus and have been seen in coastal areas, might be the source, perhaps through seals playing with a dead animal.

Professor Harwood said: "No one knows the means of transmission but it is the susceptibility of North Sea seals that is the problem. It is like the Conquistadors arriving in South America and wiping out the Indian population with the common cold. A single individual who travels large distances can spread the virus over a vast area."