Experts say new Chinese SARS case does not mean disease will be seasonal

Main Category: Flu / Cold / SARS
Article Date: 06 Jan 2004 - 0:00 PDT


Confirmation of a new case of SARS in China - the first non-laboratory acquired case in over half a year - is renewing concerns about the possible annual re-emergence of the potentially deadly and disruptive disease.

But one case does not prove SARS will follow the pattern of influenza, experts insisted Monday. 'This is an isolated case, the first that we've seen in several months. And therefore it doesn't give us any more information than we had before whether or not it's seasonal,' said Dr. Donald Low, a leading Canadian SARS expert.

Since severe acute respiratory syndrome burst from behind a veil of Chinese secrecy last spring and sparked outbreaks that threatened health care systems and economies around the globe, infectious disease experts have been debating the future of SARS.

Some contend it will become like influenza, going under the radar in the warm summer months but reappearing each winter when conditions for spread are more favourable.

Others argue the disease was not an effective enough pathogen in humans to gain a permanent place in the spectrum of seasonally circulating respiratory viruses, though it may occasionally jump from its animal source - which still hasn't been fully confirmed - to infect an individual or two.

Low has been among the most vocal in this latter camp. As luck would have it a commentary he wrote declaring that SARS would not return is being published in Tuesday's issue of the Canadian Medical Association Journal. (The commentary was published online last month and received widespread media attention at the time.)

He insisted Monday the single case in China does not disprove his theory, noting the case did not trigger an outbreak.

'I would have rather not have seen it happen. There's no question about that. But now that it's happened, I think that it's reassuring that we didn't see transmission to anybody. And China's obviously on the ball. They're ready to recognize cases like this.'

A spokesman the World Health Organization didn't dispute that theory, but said it is just too soon to say.

'This case certainly doesn't tell us that this is a seasonal disease,' said Dick Thompson, director of communications for the WHO's communicable diseases division.

'It might tell us that SARS could . . . reappear from time to time. It tells us that until we identify the source and eliminate it, we're probably always going to have to have heightened surveillance systems to identify cases early.'

Studies conducted last spring showed civet cats, wild animals eaten as a delicacy in southern China where the disease first emerged, can be infected with the coronavirus that causes SARS in humans.

It remains unproven, however, that they are the source of the human disease. The handful of cats tested could have been infected by other animals in the markets or by their human handlers.

Still, China has announced that 10,000 civet cats seized from the wild animal markets of Guangdong will be slaughtered in a bid to contain the disease.

Low suggested those worried about the future of SARS might find more answers looking to monkeypox than to influenza.

Monkeypox is a virus from the smallpox family that can infect a variety of small animals and can occasionally jump from animals to humans. In Africa, where it is most common, monkeypox kills between one and 10 per cent of humans who contract it.

The United States had an outbreak of monkeypox last summer; the source was traced to imported animals from Africa which infected prairie dogs sold in pet stores. About 80 people contracted the disease, though none died.

'So I think the worst case scenario would be in that in the future, we would expect every once in awhile to see transmission from animals to humans. But with good surveillance, recognition of the disease and using precautions, we won't see more than an isolated case or contained transmission,' Low said.

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