The National Veterinary Institute has isolated the deadly virus in several live river gulls that were caught two weeks ago together with some 70 other birds in the Pantan reserve, near the southern coastal resort town of Trogir, after two dead swans found in the same area had tested positive for the H5N1 strain, Kovacevic said.
Veterinary Institute official Vladimir Savic told Hina that the Pantan gulls were diagnosed with the highly pathogenic H5N1 virus on Monday. "It is hard to say whether the swans were infected by the gulls or the other way round," he said.
The virus has not been found in other live or dead birds in the area, and the swans believed to be belonging to the same flock as the two dead infected swans flew away two weeks ago when the catching of birds began.
In mid-February, an infected swan was found dead at Slatine on the island of Ciovo, about five kilometres from Pantan as the crow flies, and another one was found in the close vicinity of the reserve.
No new measures will be imposed in the Trogir area after the latest discoveries, because all poultry has already been culled within three kilometres of the sites where the two dead swans were found. All poultry owners within a 10-km radius have been ordered to keep their birds indoors.
Authorities will increase the monitoring of wild birds and their migrations from and to Pantan, where about 200 bird species have been registered.