Outbreak has bird-flu experts stumped

Several of the world's foremost disease detectives have congregated in a remote village in Indonesia to investigate the largest cluster of deaths from bird flu yet discovered.

Though seven members of one family have died of avian influenza in the village in the last three weeks, public health experts say there's no reason to believe human-to-human transmission of the virus is becoming more common.

The illness has not been found in anyone in the area--a remote island in Sumatra--outside of the one family. Nor is there any sign that the H5N1 influenza virus has mutated to become more dangerous to humans.

"We're not seeing anything that's sending up an alarm," Dr. Julie Gerberding, chief of the U.S. Centers for Disease Control, said in a Wednesday afternoon briefing.

A World Health Organization spokeswoman said the agency would leave its pandemic alert warning unchanged at Level 3, meaning "no or very limited human-to-human transmission."

Yet the situation in Indonesia is intriguing for several reasons.

For one, it's not clear where the infection came from. None of the animals tested in the area have shown evidence of the H5N1 virus that killed the family members, the WHO reports.

"This is the first time that we've been completely stumped" by a source for the infection, said Peter Cordingley, spokesman for the Western Pacific Region of the WHO.

And it remains unclear if the family members transmitted the deadly illness to one another or if all were infected by a source yet to be identified.

The great fear with bird flu is that the virus will undergo a genetic change that could promote easy human-to-human transmission and lead to a deadly pandemic. Currently the primary way humans become infected is through close contact with infected birds.

If this turns out to be a case of people catching bird flu from each other, it wouldn't be the first. At least three prior cases of family members circulating the disease have occurred over the last several years, said Maria Cheng, a spokeswoman for the WHO.

In Thailand, an 11-year-old girl infected her mother and her aunt in September 2004 after the two women spent hours at the girl's bedside caring for her. All three died. Two family clusters in Vietnam appear to fit a similar pattern. Yet another cluster appeared earlier in Indonesia.

But this could be the first time one person conveyed the virus to another person who then infected a third person--a worrisome development if verified, experts said.Public health officials suspect that a 38-year-old woman in the Indonesian village infected two of her sons at a dinner April 29, when she was coughing heavily in a small room. Six days later, the woman died and was buried without being tested for avian influenza. Her two sons and four other family members, including a 10-year-old boy, subsequently died and were found to have the H5N1 virus.

The woman's brother, who was also in the room, became infected and is being treated in the hospital.

"All confirmed cases in the cluster can be directly linked to close and prolonged exposure to a patient during a phase of severe illness," the WHO noted in its most recent statement on the Indonesian outbreak. "Although human-to-human transmission cannot be ruled out, the search for a possible alternative source of exposure is continuing."

Prolonged contact could increase the likelihood of infection by exposing a person to a large amount of the virus.

"It seems that most humans who have been infected have been infected with extraordinarily high viral doses," said Robert Lamb, professor of molecular and cell biology at Northwestern University. Or, it could be that very sick people are more likely to transmit the bird flu virus, said Andrew Pekosz, assistant professor of molecular microbiology at Washington University School of Medicine.

•	Outbreak has bird-flu experts stumped Did 7 relatives transmit virus to one another? So far, sleuths have turned up few answers Chicago Tribune, Thursday, May 25, 2006 Byline: Judith Graham, Tribune staff reporter

	Story also ran in 11 others:  International News Service (Australia), Knight Ridder Tribune News Service, Kansas City Star, Myrtle Beach Sun News (SC), The State (SC), Biloxi Sun Herald (MS), Monterey County Herald (CA), Macon Telegraph (GA), Charlotte Observer (NC), Kentucky.com and San Luis Obispo Tribune (CA)