January 25, 2005
By Julie Sevrens Lyons
Mercury News
Raising concerns that a form of bird flu is poised to cause a worldwide pandemic, health officials announced Monday that the disease has indeed spread among humans in Thailand, killing one woman and sickening another.
They are the first well-documented cases of human-to-human spread of the strain of avian influenza that has killed countless flocks of poultry in Asian countries and necessitated the culling of entire farms of chickens.
The occurrence is worrisome to scientists, who have been concerned since the first outbreak of this virus in 1997 that it could one day mutate and easily infect mammals -- or join forces with human influenza viruses to produce a super-bug capable of killing people as quickly as it has felled chickens.
But Thai and U.S. public health officials emphasized in a study released Monday in the New England Journal of Medicine that there is still no evidence that the virus ``has gained the ability to transmit itself from person to person more efficiently.'' For now it appears that at least one more step would be needed for the virus to cause a global problem among humans.
The three human influenza pandemics in the 20th century -- including the 1918-1919 ``Spanish flu'' and the ``Hong Kong flu'' of 1968-1969 -- all stemmed from the mingling of a human virus with an avian influenza virus.
``We really are not sure when, or whether, the type A (H5N1) virus will start to spread among humans, but we must be ready to stop it if we can -- and, if we cannot, at least to mitigate its effects,'' wrote Dr. Arnold S. Monto, a professor of epidemiology at the University of Michigan School of Public Health, in an accompanying editorial.
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