Bird Flu: Science and Policy

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World reknowned influenza expert Dr. Arnold Monto gave some comments to Reuters today regarding the recent cluster in Indonesia, along with a few other scientists.

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By Maggie Fox, Health and Science Correspondent

WASHINGTON, May 24 (Reuters) - A suspicious-looking cluster of human bird flu cases in Indonesia illustrates just how difficult it will be to detect the beginning of a pandemic, should one occur, scientists said on Wednesday.

The World Health Organization issued assurances on Tusday that the virus had not changed into a clearly dangerous form, but experts said if it had changed, the information would have come much too late.

In fact, they said, the only way anyone will know that a dangerous form of the virus is circulating will be when people start to become sick and die in large numbers.

"We are not going to know it until a lot of people are infected," said Dr. Eric Toner, an expert in emergency medicine at the Center for Biosecurity at the University of Pittsburgh Medical Center.

And the canaries in the mine will be people trying to cope with the outbreak.

"If it being transmitted efficiently, we would see health care workers being sick," Toner said.

High technology genetic sequencing may give some answers after the fact, but the only way to actually detect a beginning epidemic will be after it has already started, using old-fashioned epidemiology -- the study of a disease's impact on a population.

"We have to, because the genetics of the virus is going to come too late," said Dr. Arnold Monto, an expert in infectious disease epidemiology at the University of Michigan. It takes days or weeks to completely sequence the eight genes of a flu virus.

WHO hopes that countries will be able to quickly identify and isolate human cases of bird flu while investigators check to see how dangerous the strain is.

But the case in Indonesia shows this does not often happen in the real world.

"We are going to be making some crucial decisions based on very incomplete information and speed is of the essence here," said Michael Osterholm, an infectious diseases expert at the University of Minnesota.

And nothing happened speedily in Indonesia. "The first cases were in late April," Osterholm said. WHO issued its first definitive statement on the situation on Tuesday -- nearly a month later.

Had efficient and sustained human transmission been underway, that would be time for many people to have been infected.

The H5N1 avian influenza virus is still almost exclusively a bird virus. It has killed or forced the culling of hundreds of million of birds as it has moved through Asia, across Europe and into many parts of Africa.

It only occasionally infects people -- 218 in 10 countries, killing 124 of them. But only a few genetic changes would allow the virus to easily infect people, and it would likely sweep around the world if this happened, killing millions.

Scientists fully expect the occasional human case of avian flu. But they become more concerned when they see a cluster, like the case of the seven family members in the northern part of Indonesia's Sumatra island.

So far everyone known to have been infected was either in close contact with an infected bird, or in very close contact with an infected person -- and in fact, with a blood relative, which suggests some people may be genetically susceptible to infection.

But in Indonesia it is not yet clear how the first victim in this cluster, a 37-year-old woman, became infected.

Scientists were reassured by the first genetic analysis of virus samples taken from some of the Indonesian patients, although no one is certain of all the genetic changes that would be needed to allow the virus to infect many people.

"We do know some of the things to look for -- we know some of the virulence elements," Monto said.

"But I think the proof in the pudding is watching what happens in the region."