STOCKHOLM, June 22 (Xinhua) -- Over 1,000 black-headed gulls that were recently found dead in southeastern Sweden had been infected with avian influenza, the Swedish National Veterinary Institute (SVA) said on Thursday.
Most of the gulls were nesting in a colony in the city of Kalmar, but dead birds have also been found in other areas around the city, SVA said.
Tests have now confirmed that they were infected with highly pathogenic avian influenza of the H5N1 type, SVA said.
"In a short time, we have seen extensive mortality caused by avian influenza among black-headed gulls in different parts of the country," Karl Stahl, state epizootiologist, said.
In April and May, more than 1,100 black-headed gulls died of H5N1 in outbreaks in Stockholm.
"The reason is that there is currently a bird flu variant circulating that is particularly well-adapted to gulls, combined with the fact that black-headed gulls nest and live closely in colonies," Stahl explained.
SVA also urged poultry farmers to be vigilant.
"There may be a risk of spread to surrounding areas, so it is important to protect poultry from infection," Stahl said.
Six foxes were also infected with H5N1 in connection with the Stockholm outbreak, SVA said in a report released on June 2. SVA has therefore urged dog owners to be cautious.
Although the Public Health Agency of Sweden has said that the likelihood of humans being infected is very low, the authority advised the general public to avoid contact with dead birds, or those displaying symptoms of illness. ■