1918 flu's ferocity surprises researchers
By ASSOCIATED PRESS
Published January 18, 2007
WASHINGTON - Scientists who tested monkeys with the resurrected 1918 killer flu virus now have a better idea of how the deadliest epidemic in history attacked and killed so many people - by energizing the victims' own immune systems.
Those findings in a first-of-its-kind experiment also help explain why so many of the roughly 50-million who died in the Spanish flu pandemic were young and healthy. Based on what was seen in monkeys, the human victims' strong immune systems likely were overstimulated, causing their lungs to rapidly fill with fluid.
"Essentially people are drowned by themselves," said University of Wisconsin virology professor Yoshihiro Kawaoka, lead author of a study being published today in the journal Nature.
Scientists believe the results open a window into what could happen if the current bird flu in Asia morphs into a lethal strain that spreads easily among people.
The 1918 virus was reconstructed with reverse genetics, relying on tissue from victims of the early-day flu pandemic. The virus is kept in only two labs where scientists are studying it: the U.S. Centers for Disease Control and Prevention in Atlanta and the Public Health Agency of Canada's lab in Winnipeg, where the monkey experiment was done.
When seven macaques were given the virus at the high-level biosafety lab there, scientists were struck by how suddenly and overwhelmingly the flu struck. The virus spread faster than a normal flu bug and triggered a "storm" response in the animal's immune systems.
Their bodies' defenses went haywire, not knowing when to stop, researchers said. The lungs became inflamed and filled with blood and other fluids. The scientists believe the virus had the same effect on humans in 1918.
The macaque experiment was supposed to last 21 days, but after eight days the monkeys were so sick - feverish, in pain, and struggling to breathe - that ethical guidelines forced the researchers to euthanize them.
If bird flu spreads person-to-person, scientists believe understanding the 1918 virus may give them clues about how to protect people from the new one.
[Last modified January 18, 2007, 00:26:05]
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