There are frequently news stories about cases of avian influenza turning up in humans in Asia, but rarely is the undertone of alarm explained in any detail: one can easily be left with the impression of "so what -- some chicken farmers got a little too intimate with their product," or "gee, you hear about this every year." However, you might want to familiarize yourself with the issue.
It turns out that direct bird-to-human viral transmission is a new and deadly shortcut.
In his book
Global Brain, Howard Bloom fills in the
back-story of global flu pandemics and the current focus on avian outbreaks. For starters, the flu can be a lot more than wintertime sniffles and aches. The Spanish flu of 1918 killed 20 to 40 million people in a matter of months, including 675,000 Americans. The Asian flu of 1957 killed 70,000 people in America alone; the 1968 Hong Kong flu, another 35,000. The origins remained a mystery. After the 1968 outbreak, researchers at the St. Jude Children's Research Hospital began looking into it.
One of them, Robert Webster, suspected that spread of the disease was due in great part to migrating birds, and over the years he pieced together a picture of how these outbreaks occur. He found that waterfowl were carriers of the highly-mutatable influenza type A, the same type of virus responsible for the Spanish flu. These birds typically pick it up in its dormant state in Arctic regions, and then migrate down the Asian continent where they leave their droppings in the barnyards of China.
At that point, chickens become infected, and then pass it on to domestic pigs, in which viruses able to infect humans have long since been established. Apparently, that's the usual route taken by the virus, which is then in a familiar enough form that our immune systems and vaccines can counter it effectively. However, since the virus is mutating with each hop, the further "upstream" it is, the less familiar. If some mutations occur that enable the virus to be
transmitted directly from birds to humans, there is increased cause for concern.
In 1997, that is just what happened. Webster's team identified a particularly virulent strain of influenza type A known as H5N1 that had killed most of the chickens on several farms in Hong Kong; however, it was unusual in that the virus had bypassed pigs and had gone directly from Hong Kong's chickens to one of its citizens -- it had arrived in a form for which neither the human body nor modern medicine had developed a defense; it was totally unfamiliar to the human immune system. If the virus were to develop the capacity to move easily from human to human, it would spell big trouble.
Fortunately, Hong Kong public health officials acted quickly and
culled the entire poultry population, an estimated 1.5 million birds, within three days. This rapid response is thought by many experts to have averted an influenza pandemic. The workings of this flu virus were so unfamiliar to the immune system that according to Webster,
it could have wiped out "half the world's population"-- that's 3 billion victims.
Meanwhile, health officials track the virus as it makes its way around Asia, mutating and picking up new genes along the way. This makes it a moving target for development of vaccines, but the World Health Organization does have a
vaccine-production plan in place if an outbreak occurs among humans. The main question is whether it will be timely enough to stop the spread. Short of that, prevention seems to be the
best strategy, with organizations like
WHO and the
Centers for Disease Control monitoring outbreaks of avian flu, ready for rapid containment and intervention.
See also:
www.commondreams.org/views04/0930-16.htm