Vietnamese medical officials have reported more suspected cases of a potentially deadly avian flu strain, including five members of one family. The cases raise new fears of a pandemic if the virus mutates to spread easily among humans.
Vietnamese health officers say it is most likely that the five members of a family of farmers in northern Hai Phong province who have tested positive for the H5N1 strain of avian flu caught it from the chickens they raised.
About a month ago, as their chickens started getting sick and dying, the family ate some of the dead birds so they would not go to waste. But such "family clusters" of the illness are worrying scientists, who say they cannot be sure that family members are not passing the disease to each other.
Hans Troedsson, the World Health Organization's Vietnam representative, says that if the virus mutates to spread more easily among humans, a massive epidemic could sweep the world. So scientists are carefully monitoring multiple cases.
"We know that the virus has the capability without being changed, to in a very limited way, being transmitted from a human to another human," he said. "But of course we want to see that there is not easily transmission from human to human because that could be the first sign or indication that the virus has changed."
The H5N1 flu strain has killed at least 49 people in Asia in the last two years - far fewer than diseases like malaria and tuberculosis. Since the first outbreak in 1997 in Hong Kong, scientists have been especially worried about this avian flu - not because of how deadly it is now, but how lethal it could become, especially if it changed to easily spread among humans.
The Hai Phong family cluster is Vietnam's third. Mr. Troedsson says there is no reason to panic, but adds that detecting when the virus mutates is one of the few weapons available to the medical community. And that is why the Vietnamese authorities and the WHO are warily watching the Hai Phong case.
"We advised the government, the Ministry of Health, to thoroughly investigate this. It's important," said. Mr. Troedsson. "All cases should be thoroughly investigated, but since this is a cluster of five people in the same household, we need to find out what the source of the infection could be."
While scientists watch and wait, avian flu is slowly spreading. On Wednesday, doctors reported four more suspected cases in Vietnam. Two are neighbors of the family in Hai Phong. Authorities are investigating whether they, too, got the virus from poultry, or whether they were infected by their neighbors.
The WHO also is sending a bird flu expert to North Korea to help authorities there contain an outbreak of flu among chickens. North Korea a few days ago said some poultry farms were infected, but has not said what strain of the flu has been found.