For the last few years worried health officials world-wide have been preparing for a possible bird flu pandemic, similar to the 1918 pandemic that killed millions. Now researchers say they've broken down that 1918 influenza strain in a way that offers clues in how to cope with a modern outbreak.
Publishing their findings this week in the Proceedings of the National Academy of Sciences, the researchers say they have isolated three genes that combine to allow the virus to settle in the victims' lungs and cause pneumonia.
To reach their conclusions, they combined samples of the 1918 germs with today's garden-variety flu bug. They say their findings could lead to new flu vaccines, as well as demonstrate more clearly how a flu virus mutates.
The 1918 pandemic, which killed many young, otherwise healthy victims, was different from previous flu outbreaks in one key respect. Normally, flu is an affliction of the upper respiratory system. But in the 1918 outbreak, the infection settled deep into the lungs, causing many victims to develop pneumonia.
Scientists are worried the same thing might happen if bird flu mutates so that it can be transmitted from human to human. Currently, humans can only contract the disease from birds, but when they do the results are usually lethal. Human victims respond much the same as those who were caught up in the 1918 pandemic.
"The 1918 influenza pandemic was the most devastating outbreak of infectious disease in human history, accounting for about 50 million deaths worldwide," the authors wrote.
The research team found that combining three flu genes made the virus much stronger, allowing it to invade deeper into the lungs than a normal flu bug. The gene combo gave a normal flu germ the ability to kill laboratory animals in tests.
The challenge, say researchers, will be development of a vaccine that can attack the deadly combination of genes. Since it first appeared in Hong Kong in 1997, the H5N1, or bird flu virus, has been slowly evolving into a pathogen better equipped to infect humans. The final form of the virus, public health officials fear, will be a highly pathogenic strain of influenza that spreads easily among humans.
