Scarcity of autopsies on bird flu victims blinds science to course of disease

TORONTO (CP) - In a soon-to-be-released issue of a scientific journal, researchers from Thailand and Hong Kong will report the findings of an autopsy of a six-year-old Thai boy who died from avian influenza.

Slated for publication in the July issue of Emerging Infectious Diseases, their findings of an atypical pattern of infection - deep in the lungs, away from the tracheal lining where virus could easily be coughed out at others - may help explain why H5N1 influenza doesn't yet spread easily among people.

But the very fact that a paper containing autopsy data from a single case is still desirable to journal editors a year-a-half into the H5N1 outbreak underscores a problem that has been plaguing the scientific world's pursuit of knowledge about this dangerous strain of influenza.

While at least 54 people have died from H5N1 infections since December 2003, autopsies have been performed on fewer than a handful of cases.

For cultural and other reasons, body after body has been buried or cremated, robbing pathologists of the precious chance to chart the havoc the virus wrecks on its victims.

"That's one of the reasons why it's so difficult to understand what the virus does in the body," says Dr. Klaus Stohr, who heads the World Health Organization's global flu program.

"Did it do more damage on the intestine? Is the heart affected? Encephalitis: Yes? No? What it the damage in the lung?

"That's why post-mortems are so important. But ... there are less than five done, I think, so far. And all in Thailand."

(Thailand hasn't reported a human case in the most recent wave of infections, which began in December 2004. That means science has no autopsy data with which to try to explain the worrisome changes in infection patterns that have observed over the last six months in Vietnam, changes which flu experts fear mean the virus is becoming more transmissible and more likely to spark an influenza pandemic.)

Without information that can only be gathered through autopsies, scientists devising treatment options and potential vaccines are working, if not in the dark, then in a dim light, experts say.

"If we want to test vaccine or antiviral strategies for intervention, we would like to know what the disease looks like in humans," explains Ab Osterhaus, head of virologist at Eramus Medical Center in Rotterdam, the Netherlands.

Drugs and vaccines are tested in animals before being administered to people. But without having a clear picture of what the disease does in humans, it's difficult to select the appropriate animal model, Osterhaus says. Animals used as models must experience a pattern of infection that closely mimics human disease in order for scientists to feel secure that what they are learn might apply to people.

Determining which organs the body is attacking is also crucial from an infection control point of view, because it helps identify possible modes of transmission.

In some species, massive amounts of the H5N1 virus are excreted in feces, Osterhaus notes. Excreted virus isn't a threat with human flu viruses. But if H5N1 replicates in the human gastrointestinal tract, patients who experience diarrhea could contaminate their environments in ways health-care workers might not expect from a respiratory virus.

"So that's very important information," Osterhaus says.

The autopsy on the Thai boy found viral replication in the intestine.

Autopsies could also show whether the virus is being spread through the blood supply to other organs, says the Toronto pathologist who performed the first autopsy done on a SARS patient in Canada.

"You want to see whether the cause is in the blood supply and therefore may be a systemic or body-wide problem, or if it's organ-specific," explains Dr. Jagdish Butany, who insists autopsies provide a wealth of information for those who treat patients and those who study viruses.

"The information we continue to get out of autopsies is totally unbelievable," says Butany, a pathologist at the city's University Health Network.

But he acknowledges in certain cultures and religions, getting permission from relatives to conduct autopsies is virtually impossible. And in steamy climates like that of Southeast Asia, prompt disposal of corpses is the norm.

Even if more people were willing to authorize post-mortems, there is another problem, notes Earl Brown, a virologist who specializes in influenza virulence at the University of Ottawa.

H5N1 influenza isn't claiming its victims fast enough.

"The problem is you have to wait for the people to die and they're just not dying early enough," Brown explains. "They die after several weeks in intensive care and all the (viral) tracks are gone."

"Getting people who die from rapid, fulminant disease early to look at when everything's sort of fresh is the trick."