Lethal Bird Flu Goes From Son to Father

The World Health Organization on Friday reported the first lab-confirmed case of avian flu spreading from one person to another -- a 10-year-old boy in Indonesia who infected his father.

But health experts said there was no immediate cause for concern. Although this flu strain’s unique genetics made it relatively easy to trace from person to person, it died with its victims and was no more likely to spread between humans than other strains.

“If anything, it appears we have ducked another bullet,” said Dr. William Schaffner, an avian flu expert and chairman of preventive medicine at Vanderbilt University Medical Center.

Since the first human cases of avian flu were reported in Southeast Asia in 1997, experts have warned that the constantly mutating virus someday could spawn a pandemic.

The virus has killed millions of birds in at least 30 countries, but outbreaks among humans have been relatively rare. There have been 228 reported human cases worldwide and 130 deaths, almost all of them in Asia, according to the World Health Organization.

Health experts say the fact that avian flu kills more than half its victims makes the prospect of a pandemic particularly frightening.

In the Indonesian case, seven members of a family were infected on a remote northern island, according to Dick Thompson, a spokesman for the World Health Organization. Six of the victims died.

The first five relatives were infected with identical strains of H5N1, as the bird flu strain is known. But the virus mutated in the sixth victim, a 10-year-old boy. He passed the mutated virus to his father, Thompson said. That mutation allowed an Indonesian lab to match the strains that infected father and son, he said.

The father died about four weeks ago, Thompson said. But soon after he was infected, about 50 people that he had come into contact with were identified and closely observed for three weeks -- twice the normal incubation period for avian flu. None developed avian flu symptoms, Thompson said.

The mutation made the avian flu strain easier to identify, but did not make it any more infectious, Thompson said.

Health experts say that human-to-human transmissions of avian flu within families have occurred before. The first reported case was published last year in the New England Journal of Medicine, when researchers documented a daughter in Thailand who had infected her mother.

Initial results of an avian flu vaccine tested last year in a major clinical trial at research sites around the country were mixed. Researchers announced in March that the vaccine triggered protective immune responses in about half of those given a high dosage.

The vaccine appeared to be safe, but required such large doses that it would be difficult to make sufficient quantities for a major outbreak, researchers say.

A second vaccine is being tested nationwide on about 600 adults and another 600 people age 65 and older.