SARS spread from live markets, but when?
From ANIMAL PEOPLE, October 2003:
BEIJING–Blood tests indicate that about 1% of the children
in 17 provinces of China were exposed to Severe Acute Respiratory
Syndrome before the outbreaks of 2002-2003 that hit 24 of the 31
provinces.
Evidently passing from animals sold in filthy live markets to
humans working in food preparation, and then spreading from human to
human, SARS eventually killed 916 people in 32 nations, with about
650 of the deaths occurring in mainland China and Hong Kong.
The blood study was conducted by the Beijing Military Zone
Air Force Logistics Sanitation Unit, using samples taken from
healthy children before SARS appeared.
In a parallel study, the Beijing Capitol Pediatrics Research
Institute found that among 77 children hospitalized for various
reasons in 2001, 42% had antibodies to SARS. Among 92 children
hospitalized during the SARS outbreak, 40% had the antibodies–but
none had SARS symptoms.
Both studies indicate that the coronavirus responsible for
SARS was already widely distributed among the human population–at
least among children–well before it turned deadly. The findings may
explain why relatively few children developed the deadly strain of
SARS, but confounds the mystery of how SARS originated, since
children are also less likely than adults to consume wildlife
products.