Scientists have confirmed that an Indonesian man caught avian influenza from his son in the first human-to-human case, The New York Times reported Friday.
The World Health Organization in Geneva reported that the father and 10-year-old boy were members of a family in which seven members caught the disease and six have died. They lived in Kubu Sembilang, a village in a mountainous and hard-to-reach area of Sumatra.
Dick Thompson, a WHO spokesman, said the virus mutated in the boy, so the strain found in the father differed slightly from that found in poultry. He said the mutation did not make the virus easier to transmit or its effects more severe.
The strain found in most of the family was identical to that found in poultry, so researchers could not tell how they became infected. But Thompson said researchers have found no other cases among relatives and friends, suggesting that human-to-human transmission is still unlikely.
More than 200 people have been diagnosed with avian influenza worldwide, most of them in Southeast Asia. The mortality rate has been high, but it is possible that the disease has not been diagnosed in people with milder cases.
A slight genetic mutation of the deadly H5N1 virus has been discovered in a small fishing village in Indonesia, a World Health Organization investigation confirmed Friday.
Experts tested the H5N1 virus that infected a family of eight on Sumatra island last month. Seven of the eight patients died.
Investigators identified that a mutation occurred after the virus infected the 10-year-old boy.
The boy then passed on the new strain to his father.
While leading bird flu experts stress the mutation does not increase the likelihood of a human pandemic, it is a sign that the virus can be spread between humans.
"The mutation is only significant in that it allows confirmation of person-to-person transmission," Allison McGeer, director of infection control at Toronto's Mt. Sinai Hospital, told CTV.ca
The mutation, however, is not a significant evolution in the virus.
According to Mary Vearncombe, a University of Toronto professor of microbiology and an expert in pandemic planning, there are three main reasons why this mutation is not a cause for concern.
- The first reason is the fact that scientists expected mutations to arise as natural part of viruses, Vearncombe told CTV.ca. "Influenza viruses mutate all the time, that's what they do," Vearncombe said.
- The WHO's investigation found that the mutation does not make the virus more infectious between humans. "This particular mutation is not the kind of mutation that would make the virus easily transmissible from person-to-person," Vearncombe said.
- Since the father was the final victim, the virus died with him -- meaning there is no further source for the transmission of this particular mutated strain.
While some experts fear the H5N1 virus will eventually mutate into a strain that will easily spread among humans, officials say there is no reason to raise alarm bells at present.
Since it emerged in Asian poultry stocks in late 2003, H5N1 has killed at least 130 people.
In the past, bird flu deaths have been traced to contact with infected birds, not people.
However, the evidence from WHO's latest investigation shows that a human-to-human transmission did occur between the seven relatives living in a remote Indonesian farming village.
Up until now, Vearncombe described the rare human-spread cases as "a number of exceptions that you could count on the fingers of one hand."
"This particular family cluster has received a lot of attention because only one member of that family had contact with poultry," Vearncombe said.
It is believed only the one member in the family, who sold vegetables at a local market, was infected by poultry.
It is believed that she, in turn, spread the virus to her family.
"But those people in her family had very close contact with her -- close contact meaning that she was very ill, she was coughing a lot and they slept in the same room as her."
In order for the H5N1 virus to be transmitted between humans, it must be through large droplets that the infected person might cough out.
To date, there has been no evidence of an airborne strain of the virus.
However, what concerns health experts is the lack of information about the H5N1 strain's ability to mutate.
"Nobody knows how difficult it is, or what the barriers are to this virus evolving to becoming a human strain," McGeer said.
"We just don't know how likely it is, or how long it might take or how difficult it is for it to happen."
Indonesia and bird flu
Information about the mutated strain was released in a WHO report during a closed meeting between the world's top bird flu experts in Jakarta.
The three-day session, which wrapped up Friday, stemmed from the Indonesian health community's request for international help.
With 39 human bird flu deaths, Indonesia trails Vietnam by three deaths as the hardest-hit nation.
Indonesia's Welfare Minister Aburizal Bakrie said that his government is pursuing a strategic bird flu plan even though it is challenged by both money and manpower.
The government estimates it needs $900 million US over the next three years to successfully fight the virus.
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