SARS, the acronym and commonly known name for Severe Acute Respiratory Syndrome, is a contagious lung disease caused in humans by a rare virus. The disease, in its known form, is quite deadly, killing about 10% of known victims. Fortunately, thus far there has been only one outbreak in human beings, in 2003. However, like the more commonly feared avian flu, it is quite possible that the SARS virus is continuing to spread and mutate in a host animal population, from which it could again return to humans at some point in the future.
– Patient Zero: China –
SARS is known to have originated in rural China in 2002. In Guangdong, a farmer died of what was then an unidentified respiratory illness, but not before spreading it to both patients and medical professionals at the hospital where he was unsuccessfully treated for the unknown disease. Either because of a deliberate coverup or simple incompetence on the part of Chinese public health officials, however, the existence of a new contagious disease was not confirmed in rural China until after it had already spread to other countries. It is probable that the Chinese government’s decision to suppress media coverage of the rapid spread of a new contagious disease in Guangdong, at the very least, contributed to the difficulty with which SARS was confronted in later stages of the epidemic.
– Transmission through Hong Kong –
Rural China has very few contacts with the outside world; Hong Kong, however, is a different matter. The following February, a Chinese doctor from Guangdong visited this modern metropolis and took the disease with him to his hotel. He died there on March 4, but not before spending some time sightseeing and visiting with relatives. Within a matter of days, other people in Hong Kong, particularly those who had stayed or worked on the same floor of the hotel as the Guangdong doctor, also began to fall ill, with remarkably similar symptoms. One, an American businessman, then spread the disease to Vietnam.
In general, once a contagious illness has begun to spread into a new society with no natural immunity to it, preventing infection is almost impossible; the best goal of public health is to slow the spread of the illness. (Note, for example, the more recent attempts to combat the spread of the H1N1 flu.) In this case, the individuals involved did not realize that a new disease was spreading; consequently, individuals continued to travel and spread the disease, and health professionals failed to take full precautions to prevent disease transmission. A very high proportion of the first wave of SARS victims were therefore Asian nurses and doctors.
– Spread to Canada –
Once the disease had begun to spread to travellers in Hong Kong, its worldwide transmission was virtually assured. By April 2003, cases were beginning to appear in countries with the most widespread travel links to the Far East, such as Canada (which has a very high Chinese-Canadian resident population). In the rest of the developed world, Canada was the most serious affected country: in May, the height of its spread, thousands of suspected SARS cases were isolated in Canada, many of them nurses who had accidentally put themselves at risk of contracting it from their patients.
Fortunately, most of these cases never developed SARS; however, of the roughly 250 confirmed cases in Canada, 44 died, yielding a disturbingly high casualty rate of nearly 20% (twice the overall official fatality figure). The next most affected countries were Taiwan and Singapore. Although several Americans contracted the disease while travelling in Asia, just 27 are known to have acquired it in the U.S. itself, and none of these were killed.
– Containment –
Fortunately, outside of unprotected medical settings, SARS proved relatively uncontagious despite the initial warning signs in rural China. As a result, the disease was contained, although not before the World Health Organization began to take emergency measures, such as warning travellers away from potential disease hotbeds like Hong Kong, China, and Toronto, Canada. By the end of 2003, the rate of new cases had effectively dropped to zero. After near-panic, global public health cooperation had succeeded in containing the epidemic.
This does not mean that SARS is gone, however. It presumably – like most other viruses – mutated from another virus found in the wild in some other mammalian species, or possibly birds. Moreover, no vaccine was developed before the disease was vanquished. Consequently, it is plausible that the disease could stage a recurrence. If it did, humans would really have no more effective defences against it than we did in 2003.