Human transmission of bird flu confirmed
| Human transmission of bird flu confirmed |
By Elisabeth Rosenthal International Herald Tribune Published: June 23, 2006 |
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| An Indonesian man who died after catching the H5N1 bird flu virus from his 10-year-old son represents the first laboratory confirmed case of human- to-human transmission of the disease, a World Health Organization investigation of an unusual family cluster has concluded, the agency said Friday. The WHO investigators also discovered that the virus had mutated slightly when the son had the disease, although not in any way that would allow it to pass more readily among people. Flu viruses like H5N1 mutate constantly, although most of the mutations are insignificant biologically, as appears to have been the case in the Indonesian cluster. "Yes, it is slightly altered, but in a way that viruses commonly mutate," said Dick Thompson, a spokesman for the WHO in Geneva, describing the findings of the report, which was not publicly released. "But that didn't make it more transmissible or cause more severe disease." The greater importance of the slightly modified virus is that it allowed researchers from the WHO and the U.S. Centers for Disease Control and Prevention to document for the first time that the virus almost certainly was passed from person to person. In previous cases where human-to- human transmission was suspected, researchers could not test samples from the patients, or the virus in the patients was the same as that in poultry in the area. Scientists have long said that the H5N1 virus, which has killed hundreds of millions of birds worldwide, does not spread easily to humans or among them. But they have worried that it might acquire that ability though normal biological processes that involve genetic rearrangement. That could potentially set off a devastating human pandemic. More than 200 people have contracted bird flu worldwide, almost all of them after very close contact with infected birds. International health officials have been in Indonesia for much of the past month, investigating a family outbreak that affected seven relatives in a remote region of Sumatra. Six of the seven died. Although Indonesia has been struggling all year to control bird flu outbreaks among poultry, the family on Sumatra had no known direct contact with sick birds, although the first death was a woman who sold vegetables in a market that also sold birds. But scientists have long suspected that H5N1, though an avian virus, could also spread between people in rare cases, if there was prolonged close contact. The family members in the cluster had a banquet in late April when the vegetable merchant was already ill and coughing heavily. Some spent the night in the same small room with her. Some members also cared for their relatives when they were sick. In hospitals, doctors and nurses generally wear masks when treating potential bird flu victims. The first five family members to fall ill had identical strains of H5N1, one that is common in animals in Indonesia. But that virus had mutated slightly in the sixth victim, a child, and he apparently passed the mutated virus to his father - which allowed the lab to confirm the transmission. Still, Thompson said there was no evidence that the mutated virus was better adapted to human infection. To the contrary, the WHO has been following 54 neighbors and family members who lived near the family in the village for a month and none have contracted the virus. "So we know it is not more easily transmitted," he said. |