Nearly 5,000 of the swallows raised by a company in central Ninh Thuan Province have died for unknown causes, but eight samples of them have been found contracting the H5N1 avian flu virus, authorities reported.

Deputy chairwoman of the province’s Phan Rang-Thap Cham City, Nguyen Thi Hue, said more than 4,900 of the flock of about 10,000 swallows raised by city-based Yen Viet Trading and Service Co., Ltd. have died over the past two weeks, from March 26 to April 11.

The company has been breeding swallows at Thanh Binh Theatre on Thong Nhat Street in the city.    The  Veterinary Office for Zone 6 took samples of the dead birds for testing and the test results showed that eight dead swallows had infected with H5N1 virus, Hue said.

Nguyen Van Khoi, the owner of a swallow breeding center in the city, said, “Once swallows have contracted the virus, the transmission of pathogen is very hard to be contained, since the bird usually flies long distances to look for food and we cannot know where they have flown to.” Yesterday the Department of Agriculture and Rural Development of Khanh Hoa Province, where there are hundreds of swallow breeders, held a meeting to discuss measures to cope with possible bird flu outbreaks among swallows.

Authorities of several southern provinces where swallows are bred in large quantities such as Tien Giang, Bac Lieu and Kien Giang have also taken precaution against H5N1 virus infection.     In Ho Chi Minh City, the Veterinary Sub-department has taken 12 samples of swallows from breeding centers in Can Gio District for testing, said Phan Xuan Thao, head of the agency.

The sub-department has also strengthened control and supervision over swallow breeding in the city to detect any signs of abnormality, Thao said.

During 2012 and the first quarter of 2013, the sub-department tested a total of 94 samples of swallows and all the samples were negative with H5N1 virus, he added.

In order to protect consumers’ health, swallow nest products should be tested for H5N1 virus before they are launched on the market, since the virus can be transmitted from poultry, including swallows, to humans, said Van Dang Ky, head of the Epidemiology Division under the Veterinary Department.