Friday, February 03, 2012

The H5N1 Strain of Flu is Still a Threat

Science magazine reports that the H5N1 flu continues to be found "in poultry in much of south and southeast Asia—and the human death toll is mounting. Since the beginning of the year, the virus has killed individuals in Cambodia, China, Indonesia, and Vietnam, and there has been a case of human infection in Egypt, according to the World Health Organization (WHO) and local press accounts. WHO reports that most of the recent human cases can be traced to contact with sick birds. Since 2003, avian influenza has proved fatal in 343 of the 582 humans infected with H5N1."

People tend to mistakenly judge the threat of a disease from their personal experience with the disease. The annual flu hits most of us from time to time, and causes a self-limiting illness which is inconvenient but not very dangerous. With the increasing use of the flu vaccine, most of use modern enough to use the Internet find, the annual flu epidemic seems even less of a threat. In fact, the annual flu epidemic kills tens of thousands of people each year and is a serious (sometimes lethal) illness for the vulnerable -- small children, old people and people with compromised immune response systems.

Every once and a while a new strain of flu emerges in the human population that is highly contagious, one for which there is no human herd immunity. The H5N1 threatens to be such a strain. If the H5N1 continues circulating in birds, changing over time in the bird population, and if it continues to jump from bird to man from time to time, it may occur that a variety highly contagious in humans will make that jump. "Earlier this year, two labs created a strain of H5N1 that might do just that, spreading from ferret to ferret with ease." That high death rate from H5N1 suggests that a devastating pandemic may then occur. 

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