Emergence of SARS

Such a convergence likely occurred during late 2002 in southern China, where merchants and farmers took small wild mammals from their native environments to local markets and sold both slaughtered and live animals for human consumption. Some of these mammals most likely carried a coronavirus resembling SCoV (Guan et al., 2003). The likelihood of human exposure to the virus is quite high when the crowded and relatively unsanitary conditions of these markets are considered. As a result, SARS emerged in the southern Chinese province of Guangdong in late 2002. The index case, retrospectively identified on November 16, occurred in the city of Foshan; by mid-December, SARS had appeared in two additional cities in the province.

An expert team from the provincial government and the national Ministry of Health went to the city of Zhongshan to investigate one of these outbreaks. The team concluded on January 21, 2003, that the infection was atypical pneumonia probably caused by a viral agent. The team recommended measures for the prevention and treatment of infection and suggested that a case reporting system be established to monitor the disease. The investigative team’s findings were reported to every hospital in the province. Unfortunately, the reporting of these findings coincided with the Chinese New Year holiday. This compounded the challenge for early intervention against the disease in two ways: the report did not receive significant attention from health officials on leave; and the opportunities for disease spread were greatly enhanced by the travel that often accompanies the celebration of the New Year.³ Additionally, as we discuss later in this chapter, the medical community’s understanding of the true etiology of SARS was delayed significantly by a February announcement from a senior scientist at the Chinese Center for Disease Control that he suspected the infectious agent was Chlamydia—a commonly understood bacterial agent that would not have warranted heightened concern or investigation.

On January 31, the first hyperinfective, or superspreading, case of SARS occurred in the city of Guangzhou. The patient was transferred among three hospitals and infected an estimated 200 people, many of them hospital workers.

As these events unfolded, the international public health community began to receive news of the outbreak through e-mails, Internet chat rooms, and local media outlets, whose reports were widely disseminated through electronic reporting systems such as the Global Public Health Intelligence Network (GPHIN) and Pro-MED mail (Eysenbach, 2003). Based on this information, WHO queried the Chinese government on February 10 and received a response the following day describing an outbreak of an acute respiratory syndrome involving 305 cases and five deaths in Guangdong Province (WHO, 2003b).

Some of the most severe SARS symptoms were suffered by residents of the Amoy Gardens apartment towers in Hong Kong during an outbreak in late March that sickened more than 300 people (WHO, 2003c). Rather than its usual route of transmission by respiratory droplets, the virus is thought to have spread via aerosolized fecal matter through the internal sewer system of the apartment complex (WHO, 2003f). Consequently, on March 31, Hong Kong’s health authorities issued an unprecedented quarantine order to halt the spread of SARS on the island, which required some residents of the housing complex to remain in their apartments until midnight of April 9 (10 days later) (WHO, 2003c).

Spread of the SARS Coronavirus Beyond China

Epidemiological investigations revealed that the spread of SCoV outside China began on February 21, 2003, when 12 people staying in the Metropole Hotel in Hong Kong contracted SCoV from an infected, symptomatic physician from Zhongshan University (see Figure S-2). These 12 people subsequently carried the infection with them to Singapore, Vietnam, Canada, Ireland, and the United States—initiating chains of infection in all of these countries except for Ireland. According to WHO estimates, most of the more than 8,000 probable cases of SARS worldwide originated with this superspreader (WHO, 2003a).

FIGURE S-2

Portrait of a superspreader: spread of SARS from the Metropole Hotel in Hong Kong as of March 28, 2003.

Vietnam

Dr. Carlo Urbani, a WHO infectious disease specialist based in Vietnam, reported concerns about a patient in the Hanoi French Hospital with a high fever and atypical pneumonia to WHO’s Western Pacific office on February 28 (WHO, 2003c). Responding to Dr. Urbani’s alert and other reports of atypical pneumonia in Vietnam and Hong Kong, WHO sent GOARN teams to Hong Kong and Hanoi to join the investigative and containment efforts already underway. The early detection of SARS in Vietnam, prompt sharing of that information with the international community, and aggressive containment efforts by the Vietnamese government, in partnership with a GOARN team, enabled the Vietnamese to eradicate SARS by the end of April. This was accomplished before SARS was contained in either Canada or Singapore, despite Vietnam’s comparatively limited health care resources and lower education levels among its population. (Tragically, Dr. Urbani himself died of SARS.) It was suggested by workshop participants that containment of the disease in Vietnam was, in fact, aided by the absence of more sophisticated medical devices and facilities— such as mechanical ventilation by intubation, bronchoscopy, aerosolized medications, and large hospital facilities that exposed large numbers of individuals to undiagnosed SARS patients awaiting care—which have been identified as factors that promoted SCoV transmission considerably in Singapore and Toronto (Lee et al., 2003).

On March 12, WHO issued a global alert describing outbreaks of the yet-unnamed respiratory disease in Hong Kong and Vietnam and instituted worldwide surveillance (WHO, 2003d). A second alert on March 15 named the condition, listed its symptoms, and advised travelers to have a high level of suspicion of SARS and report to a health worker if they had SARS symptoms and had visited an area where SARS was known to be occurring. Two further alerts provided recommendations for airports to screen passengers and for travelers to avoid areas where SARS had been detected, respectively (WHO, 2003e).

Canada

Canada’s experience with SARS illustrates the importance of identifying and isolating every infected individual in stemming the spread of the disease. There, the index patient returned to Toronto from Hong Kong on February 23, developed a febrile illness that was diagnosed as pneumonia, then died at home on March 5. Her son, who cared for her, subsequently became ill and on March 7 was admitted to a hospital, where he infected many patients and members of the staff. He died there on March 13, one day after WHO issued its first global alert. In this, the first phase of the Toronto epidemic, unrecognized patients who shared rooms with the son went on to infect scores of other patients, family members, and hospital workers. This scenario was repeated in several area hospitals, as well as others around the globe, even after increased infection control measures were undertaken.

Realizing that SARS was not contained within a single hospital, Ontario declared a provincial emergency on March 26 that halted the transfer of patients among hospitals, instituted infection control measures and created SARS units within hospitals, minimized visitor access to hospitals, and established a process to screen all persons entering hospitals for symptoms of SARS. Because the spread of SARS in Toronto was largely restricted to the hospital setting, these precautions were effective in controlling the outbreak. When a second phase of SARS occurred in mid-May, after emergency measures were relaxed, it was quickly brought under control with little spread outside the affected hospital (See D. Low in Chapter 1). A similar lapse in infection control in a Taiwan hospital ignited an outbreak in mid-April (WHO, 2003g). Health authorities responded quickly by increasing surveillance, redoubling infection control measures, and launching a mass education campaign credited with reducing the time between symptom onset and patient isolation.

Footnotes

3

Workshop presentation, Yi Guan, University of Hong Kong, September 30, 2003.