The World Health Organisation says two sisters who died of birdflu in Vietnam may have contracted the illness from their brother. However this first possible case of human-to-human infection should not cause undue alarm, according to the body's representative in Vietnam Robert Dietz. "We don't feel we can discount the possibility that they got it from their brother. This would be an example of transmission of H5N1 between human beings. We don't see it anywhere else in Vietnam," he said. The brother was cremated before any tests had been carried out to prove conclusively that he had the illness, so the inter-human transmission cannot be confirmed. Although Dietz advised people to stay away from live poultry, the WHO says the flu cannot spread easily between humans and has ruled out a general travel warning for Vietnam. In Thailand, authorities say a 58-year-old has become the country's third victim of the illness. The latest death brings to 12 the total number of people killed by the virus which has infected 10 Asian countries. Despite a mass poultry cull, the United Nations' Food and Agriculture Organisation says the epidemic is far from under control. **PHOTO CAPTION*** A worker sprays disinfectant at a poultry farm in Kanchanaburi province, 150 km (93 miles) west of Bangkok, January 28, 2004. (REUTERS/Suukree Sukplang)