Seal toll set to rise

2019-03-04 08:10:00

UP TO HALF of the surviving population of common seals in Britain could still be susceptible to infection with phocine distemper virus (PDV), according to British researchers. The team, led by John Harwood at the Natural Environment Research Council’s Sea Mammal Research Unit in Cambridge, was surprised by the number of animals that have no significant immune response to the virus following last year’s epidemic. The proportion is higher than their preliminary estimates had suggested (This Week, 8 April). Most of the vulnerable animals are less than two years old. Out of 56 common seals whose blood the researchers sampled during 1989, 55 per cent had antibodies to canine distemper virus, a close relative of PDV. But of the 24 animals aged less than two years, only 12 per cent had antibodies, compared with 88 per cent of the adults. The young animals presumably escaped infection last summer. According to the researchers, the pups could be particularly susceptible to fatal infection next month, when the seals gather to moult, because of their impaired immune status (Nature, vol 339, p 670). Between a quarter and half of the common seals are susceptible, according to the team,