HANOI, March 9 (Reuters) - Bird flu has killed 100 ducks in the Mekong delta city of Can Tho in southern Vietnam, the fifth locality in the country to have detected the virus in the past three weeks, a government report said on Friday. The 58-day-old ducks, which were not vaccinated against the H5N1 virus, were found dead on Wednesday at a farm near Can Tho. Tests confirmed they had been infected with bird flu, the Agriculture Ministry's Animal Health Department said. Workers slaughtered the remaining 400 ducks in the same stock, as they have done with 11,000 chickens in three affected northern locations, including Hanoi's district of Dong Anh since late February. Can Tho, 170 km (105 miles) southwest of Vietnam's largest city, Ho Chi Minh City, borders Vinh Long province where 800 ducks were slaughtered last week to help contain the H5N1 virus. "The risk that the disease is emerging in many other areas is very high," Agriculture Minister Cao Duc Phat said in a statement on Wednesday after the case in Ha Tay province was reported. Phat called on provincial authorities to tighten monitoring their poultry stock and step up inspections of poultry trade. Vietnam has had no human cases of bird flu since November 2005, but the virus, which first arrived in late 2003, returned to poultry in the south late last year where most of Vietnam's waterfowl stock is being raised. Ducks can carry bird flu without showing any symptoms, making it more difficult to contain the virus spread. The H5N1 virus, which thrives best in cool temperatures, is likely to hit more areas in northern Vietnam where fresh cold spells have arrived in the past week. But officials said tests found no trace of bird flu in the samples from several dead ducks and chickens in the northern province of Quang Ninh. Vietnam is expected to start its next phase of vaccinating poultry in the second half of March and will allow raising and hatching waterfowl to resume from March 15. Meanwhile, bird flu cases in poultry have been reported in several other Asian countries. In neighbouring Laos, health officials confirmed on Thursday that bird flu had killed a 15-year-old girl, the first confirmed victim there of the H5N1 virus. South Korea also reported an outbreak at a poultry farm on Thursday. The H5N1 virus also struck birds in China's remote Tibet last week. The H5N1 virus has infected 275 people in 12 countries since 2003 and killed at least 167 of them in 10 countries, including 42 people in Vietnam, the U.N. World Health Organisation said.
