Severe acute respiratory syndrome and influenza: virus incursions from southern China.

Abstract

The eminent sinologist and historian, Joseph Needham, writing with his colleague Lu Gwei-Djen in the sixth volume of his mighty tome “Science and Civilization in China,” emphasized the long held Chinese conviction that “the best medicine is preventive medicine,” a conviction that goes back to the Warring States period (475–221 B.C.) when there was a flowering of philosophy and medical understanding. A Han Dynasty (206 B.C.–220 A.D.) writing concludes “A skillful doctor cures illness when there is no sign of disease, and thus the disease never comes” (1, 2). This component of the “Chinese Hippocratic Corpus,” as Needham calls it, holds just as true in today’s modern world and may be simply summed-up in one word: “awareness.” In the case of emerging infectious disease, this means “preparedness,” giving rise to “reaction.” Two thousand or so years onward in the China of today, this conviction is being sorely tested by nature with incursions of respiratory viruses from its southeastern province of Guangdong adjacent to Hong Kong. In 1997, the world was thrown into a state of alarm and high alert arising from the emergence of a potentially new influenza pandemic caused by the transmission of a highly pathogenic H5N1 influenza virus (H5N1/97) of avian origin from chickens to humans in Hong Kong (3–5). On that occasion, a pandemic was only one or two mutational events away. H5N1-like viruses were recognized in chicken and other land-based poultry in Hong Kong in 2001 and 2002 before they could infect humans (6, 7). Probably three or four mutational events from generating a pandemic influenza virus, these more recent incidents upheld the ancient ideal of preventing disease before it appears. In these cases the virus did not “escape” from Hong Kong almost certainly because of its having had sound human and animal disease and virus surveillance systems in place for some time. This led to the recognition of the source of the virus and its removal by the slaughter of poultry in live markets and on farms, or a combination of slaughter and ring vaccination on farms (6–8). Over the years, Hong Kong essentially functioned as an influenza sentinel post for the wider region, stemming from the