From mid-March to April 2003, a second major outbreak of SARS occurred in another location in Hong Kong, the Amoy Gardens Apartments, with 321 people ultimately infected (Chim et al., 2003). This outbreak was more severe clinically, with more diarrhea cases (73 percent), higher intensive care unit admissions (32 percent), and higher mortality rates (13 percent) than in the Metropole Hotel outbreak. Environmental factors (in a faulty sewage system) were postulated to have contributed to the virus spread in the Amoy Gardens via aerosolized fecal material.

SARS did not spare developed countries, even ones with modern public health systems and significant resources. Canada had an outbreak of SARS on February 23, 2003, imported from Hong Kong. A second outbreak followed in mid-May 2003 after a lapse in infection control. Also because of a delayed initial response, SARS was not controlled in China until late June 2003. By that time, over 5,000 cases had been reported. On July 5, 2003, after control of a Taiwan outbreak, WHO reported that the global SARS epidemic had been contained. However on September 8, 2003, a single case of SARS was reported in Singapore (confirmed by the CDC). This individual likely became infected via laboratory-acquired exposure to SARS coronavirus, illustrating the need for strict adherence to laboratory safety procedures required for work with BSL-3 level pathogens. The widespread distribution of SARS coronavirus samples in international labs highlights the need for vigilance in the inventory of these virus stocks. Also, adequate laboratory supervision and facilities are required to avoid future laboratory acquired infections as a possible source of new SARS outbreaks.

In December 2003–January 2004, several new SARS cases reemerged in Guangdong Province, China (Normile, 2004). For at least one case, no risk factor was identified such as a link to civets. Other postulated reservoirs including rats and cats were tested, but no final conclusions were drawn concerning the origin of this reemergent case. However, sequence data suggested that the reemerged SARS coronavirus strains were more like the civet isolates (Normile, 2004), and China ordered the destruction of large numbers of civets in its wildlife markets (Watts, 2004). Recent data based on serology suggest that some SARS antibody seropositives occurred in Hong Kong in 2001 before the documented SARS outbreaks, suggesting that low numbers of subclinical SARS infections likely occur (Zheng et al., 2004). Thus both animal reservoirs and subclinically infected humans remain potential sources for the reemergence of SARS.

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