Coordinated response to SARS, Vancouver, Canada.Two Canadian urban areas received travelers with severe acute respiratory syndrome (SARS) before the World Health Organization issued its alert. By July 2003, Vancouver had identified 5 cases (4 imported); Toronto reported 247 cases (3 imported) and 43 deaths. Baseline preparedness for pandemic threats may account for the absence of sustained transmission and fewer cases of SARS in Vancouver. ********** In Canada, 2 urban areas received returning travelers infected with severe acute respiratory syndrome associated coronavirus (SARS-CoV) from the original Hotel M cluster in Hong Kong. These travelers returned to Canada before the World Health Organization (WHO) issued its first global alert on March 12, 2003. One infected traveler from Hotel M returned to the greater Toronto area (GTA, population 4.7 million), Ontario; 2 returned to the Vancouver census metropolitan area (VCMA, population 2.0 million), British Columbia (BC). GTA, Ontario, is located in central Canada [approximately equal to]4,000 km from VCMA, BC, which is the westernmost province of Canada. Control of SARS in both GTA and VCMA was by a national, publicly funded, but provincially administered healthcare system. Whereas GTA experienced sustained transmission, VCMA did not. Ultimately, GTA reported 247 patients with SARS and 43 related deaths; 3 cases were imported. VCMA identified 5 confirmed cases, 4 of which were imported (1-5). The experience with SARS in Vancouver highlights how a well-coordinated response of baseline precautions, reinforced through timely public health alerts and periodic infection control audits, can mitigate outbreaks due to emerging respiratory-borne pathogens. The Outbreak Neutralization antibody titers to SARS-CoV among patients in VCMA are shown in Table 1. SARS-CoV was also confirmed in all but patient 1 by reverse transcription polymerase chain reaction with multiple distinct primer sets applied to multiple specimens (3,6-9). Patient 0 and patient 1 were a couple, who stayed on the 14th floor of Hotel M from February 20 to 24, 2003, and again from March 3 to 6. Both became ill on February 26 (Table 2). They returned to Canada on March 6 and went directly from the airport to their physician in Vancouver on March 7 (day 9 of illness). The husband (patient 0) was sent directly to the emergency room of a tertiary-care hospital (hospital A), arriving at 1:55 p.m. Within 15 minutes, full respiratory precautions were instituted. He was moved to a private room in the emergency room at 2:20 p.m. and transferred to a negative-pressure isolation room (NPIR) at 4:20 p.m. He was admitted into an NPIR of the intensive care unit (ICU) with full respiratory precautions at 6 a.m. on March 8 (Table 2). His wife, patient 1, was recovering from mild illness, and no further follow-up was arranged. The couple had no other household contacts. Review confirmed that symptoms had not developed in any of the 148 hospital workers involved in patient 0's care by 10 days after his arrival at the hospital. The family physician had no detectable neutralizing antibody to SARS-CoV when tested at day 496. Patient 2 of the VCMA had prolonged contact abroad with 2 family members in Hong Kong, who subsequently died from SARS. Although asymptomatic, she went to her physician in VCMA on March 26 because she was concerned about her exposure. Chest radiograph showed bilateral consolidation, and she was directed, masked, to hospital B, where she was admitted directly to an NPIR. She was transferred to the ICU of hospital C for assisted ventilation (Table 2). Neither of her 2 household contacts had detectable SARS-CoV antibody at day 215. Patient 3 stayed at Amoy Amoy (ämoi`): see Xiamen, China. Gardens March 28-30 (10). Upon return, he remained self-isolated in the VCMA in the basement suite of his home with no contacts (household members were nevertheless quarantined, but they remained asymptomatic). Masked and short of breath, he sought treatment at hospital A on April 3. Initial chest radiograph was normal, but computed tomography scan showed widespread, patchy, ground-glass opacification 1. the development of an opacity. 2. the rendering opaque to x-rays of a tissue or organ by introduction of a contrast medium. o·pac·i·fi·ca·tion ( -p of both lungs. He was admitted to hospital D directly to
an NPIR (Table 2). His son, who drove him to hospital masked, had no
detectable antibody to SARS-CoV at day 200.Patient 4 of the VCMA was a nurse who cared for patient 2 at hospital B from March 29 to 30. At the time, patient 2 was receiving oxygen by mask and nebulization nebulization /neb·u·li·za·tion/ (neb?u-li-za´shun) 1. conversion into an aerosol or spray. 2. treatment by an aerosol. therapy. Patient 4 assisted patient 2 in
using the toilet, which was flushed with lid raised in her presence. She
followed guidelines in place at the time, but these did not include eye
protection. Symptoms developed in the nurse on April 4. She went to
hospital E on April 15, where she was admitted directly to an NPIR. Her
only household contact remained asymptomatic. Neither he, nor a
physician who examined her on April 11, had detectable SARS CoV antibody
at 200 and 365 days, respectively.All 5 patients with SARS in VCMA recovered fully. No additional unrecognized spread was evident. None of 442 staff members of hospitals A-E who participated in a voluntary serosurvey serosurvey /se·ro·sur·vey/ (-sur´va) a screening test of the serum of persons at risk to determine susceptibility to a particular disease. had detectable SARS-CoV antibody by microneutralization assay (details available from corresponding author, upon request). Conclusions Mathematical models for SARS, incorporating contact network theory, stress the importance of patient 0 in predicting the likelihood of an epidemic (11). This likelihood can be determined by the transmissibility of the agent, number of contacts of patient 0, and number of persons infected between patient 0 (the first patient infected) and intervention on the index patient (the first recognized case-patient). From this perspective, the circumstances of patient 0 in Vancouver compared to patient 0 in the Toronto, Canada, outbreak, merit closer examination. Approximately 2,000 passengers land in Vancouver on direct flights from Hong Kong and mainland China every day compared with 500 on average to Toronto. As such, Vancouver is a potential gateway to North America for emerging pathogens from Asia. Because of this perceived risk, the BC Centre for Disease Control (BCCDC BCCDC - British Columbia Center for Disease Control) had been increasing preparedness for pandemic threats for several years. An electronic distribution system was established to regularly disseminate communicable disease bulletins to healthcare facilities across the province. When a cluster of unexplained atypical pneumonia in China was reported almost simultaneously with reemergence of influenza A H5N1 in Hong Kong, BCCDC used this well-established communication network to issue an alert on February 20, 2003. The alert requested enhanced vigilance for severe influenzalike illness in returning travelers from mainland China or Hong Kong or among their close contacts. Alerts were repeated February 24, February 28, and March 12, 2003. Before patient 0's arrival, the emergency room at hospital A also participated in an infection control audit that emphasized that barrier precautions should be applied with all acute-onset respiratory infections. Patient 0 thus became the index patient in VCMA and was managed cautiously, even before WHO special alerts were issued. He sought treatment at the cusp of his peak infectious period at a tertiary-care hospital that had been repeatedly primed towards precaution. As a returned traveler, he was a first-generation case. He had no family contacts other than his wife, with whom he had traveled. Infection control precautions were implemented almost immediately upon his arrival at the hospital, limiting opportunities for spread. When SARS arose in Ontario, a comparable agency to BCCDC did not exist. Responsibility for communicable disease control had shifted over the course of several years to local health boards, which created a decentralized system (12). Patient 0 in Toronto also stayed at Hotel M with her spouse from February 18 to 21. She returned to the GTA on February 23 to an apartment she shared with 5 family members (5,13). She died at home on March 5. During this period, she infected her 43-year-old son. This son became Toronto's index patient, a locally acquired, second-generation case (5,13). He went to a community hospital on March 7, the same day as Vancouver's patient 0, but was not recognized as a special threat. He was placed in general observation in the emergency room, where he remained for 18 hours and where he was given nebulized salbutamol salbutamol /sal·bu·ta·mol/ (sal-bu´tah-mol) albuterol. sal·bu·ta·mol (s l-by . He was not placed in airborne isolation
until he had been at the hospital for 21 hours; droplet and contact
precautions were later begun on March 10 (5,13). By the time WHO issued
its global alert, at least 14 persons in GTA had already become infected
through 4 generations of spread: half within patient 0's family and
the remainder among healthcare contacts. Concern about severe illness in
family members as they sought treatment at the hospital prompted an
evening phone consultation on March 13 from an infection control
practitioner in Toronto to the BCCDC in Vancouver. This call linked the
separate Toronto and Vancouver cases to events in Asia and led to
recognition that SARS had spread beyond that region. It also prompted
WHO to issue a rare travel advisory on March 15 (14). Thereafter,
awareness of precautions to be taken was enhanced everywhere, and
further importations into Canada (Vancouver and Toronto) did not result
in spread.Ultimately, standard droplet and contact precautions proved an effective barrier to SARS except in the context of superspreading events such as aerosolizing procedures (3). Low inherent transmissibility, combined with the delay in peak infectivity until well into the course of serious illness, may explain why SARS was primarily a nosocomial infection and why so few countries experienced outbreaks (3). Patient 0 tests the baseline capacity of a system to respond to emerging threats before they are known or recognized. While favorable random chance may have played a role, Vancouver's response to SARS should not be dismissed on the basis of luck alone. Pasteur's edict that "chance favors only the prepared mind" may have modern relevance to the prepared healthcare system (15). The response to patient 0 in Vancouver highlights the importance of central coordination, baseline preparedness at the local level, and an efficient network of communication in mitigating outbreaks. Baseline preparedness should include barrier precautions in the care of all acute-onset respiratory infections. These should be reinforced through timely public health alerts and periodic infection control audits. Acknowledgments We thank the patients who generously shared their experience with SARS illness. We acknowledge the health professionals who, during a period of great uncertainty, provided selfless care to them. This study was funded by the Canadian Institute for Health Research and the BC Centre for Disease Control. Dr Skowronski is an epidemiologist at the BC Centre for Disease Control, responsible for surveillance, program and policy recommendations, and research related to respiratory-borne and vaccine-preventable diseases. References (1.) World Health Organization. Consensus document on the epidemiology of severe acute respiratory syndrome (SARS). Report no. WHO/CDS/CSR/GAR/2003.11. Geneva: The Organization; 2003. (2.) World Health Organization. Severe acute respiratory syndrome (SARS): report by the Secretariat. Report EB113/33 Rev. 1. 1-23-2004. Geneva: The Organization: 2004. (3.) Skowronski DM, Astell C, Brunham RC. Low DE, Petric M, Roper RL, et al. Severe acute respiratory syndrome: a year in review. Annu Rev Med. 2005:56:357 81. (4.) World Health Organization. Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. [cited 2004 Sep 20]. Available from: http://www.who.int/csr/sars/country/ table2004_04_21/en (5.) Poutanen SM, Low DE, Henry B, Finkelstein S, Rose D, Green K et al. Identification of severe acute respiratory syndrome in Canada. N Engl J Med. 2003:348:1995-2005. (6.) World Health Organization, Sampling for severe acute respiratory syndrome (SARS): diagnostic tests. 2003 Apr 29. [cited 2004 Sept 20]. Available from http://www.who.int/csr/sars/sampling/en/ (7.) Guo JP, Petrie M, Campbell W, McGeer PL. SARS coronavirus peptides recognized by antibodies in the sera of convalescent cases. Virology. 2004;324:251-6. (8.) Adachi D, Johnson G, Draker R, Ayers M. Mazzulli T, Talbot PJ, et al. Comprehensive detection and identification of human coronaviruses, including the SARS associated coronavirus, with a single RT-PCR assay. J Virol Methods. 2004;122:29-36. (9.) Tang R Louie M. Richardson SE, Smieja M, Simor AE, Jamieson F, et al. Interpretation of diagnostic laboratory tests for severe acute respiratory syndrome: the Toronto experience. CMAJ CMAJ - Canadian Medical Association Journal. 2004:170:47-54. (10.) Yu ITS. Li Y, Wong TW, Tam W, Phil M, Chan AT, et al. Evidence of airborne transmission of the severe acute respiratory syndrome virus. N Engl J Med. 2004:350:1731-9. (11.) Meyers LA, Pourbohloul B, Newman MEJ MEJ - Meadville, Pennsylvania (Airport Code) MEJ - Mouvement Eucharistique des Jeunes (Organistion Catholique), Skowronski DM, Brunham RC. Network theory and SARS: predicting outbreak diversity. J Theor Biol. 2005:232:71-81. (12.) Lim S, Closson T. Howard G, Gardam M. Collateral damage: the unforeseen effects of emergency outbreak policies. Lancet Infect Dis. 2004;4:697-703. (13.) Varia M. Wilson S. Sarwal S, McGeer A, Gournis E. Galanis E. Investigation of a nosocomial outbreak of severe acute respiratory syndrome (SARS/in Toronto, Canada. CMAJ. 2003:169:285-92. (14.) Patrick DM. The race to outpace severe acute respiratory syndrome (SARS). CMAJ. 2003;168:1265-6. (15.) Pasteur L. Lecture. University of Lille. 1865 Dec 7. Address for correspondence: Danuta M. Skowronski, BC Centre for Disease Control, 655 West 12th Ave, Vancouver, BC, Canada: tax: 604-660-0197; email: danuta.skowronski@bccdc.ca * British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada; ([dagger]) Vancouver Coastal Health, Vancouver, British Columbia, Canada; ([double dagger]) Fraser Health, New Westminster, British Columbia, Canada; ([section]) Royal Columbian Hospital, New Westminster, British Columbia, Canada; ([paragraph]) St. Paul's Hospital, Vancouver, British Columbia, Canada; #University of British Columbia, Vancouver, British Columbia, Canada; ** National Microbiology Laboratory, Winnipeg, Manitoba, Canada; and ([dagger] [dagger]) Mount Sinai Hospital, Toronto, Ontario, Canada
Table 1. SARS CoV antibody titers by microneutralization assay in
persons with laboratory-confirmed SARS in VCMA *
Patient 0 Patient 1
Serum sample Days after Days after
no. onset Titer onset Titer
1 10 1:32 16 1:128
2 19 1:128 29 1:32
3 45 1:32 637 1:64
4
5
Patient 2 Patient 3
Serum sample Days after Days after
no. onset Titer onset Titer
1 4 <1:8 3 <1:8
2 14 1:32 36 1:128
3 20 1:128 224 1:128
4 217 1:128 466 1:64
5 481 1:64
Patient 4
Serum sample Days after
no. onset Titer
1 11 <1:8
2 28 1:32
3 203 1:128
4 463 1:64
5
* By number of days after symptom onset that serum was collected. SARS,
severe acute respiratory syndrome; CoV, coronavirus; VCMA, Vancouver
census metropolitan area.
Table 2. Epidemiologic and clinical profile of patients with confirmed
SARS, Vancouver *
Patient characteristics Patient 0 Patient 1
Baseline characteristics
Sex Male Female
Age (y) 55 54
Medical condition No Diabetes
Epidemiologic characteristics
Travel related Yes Yes
City of likely source of SARS Hong Kong Hong Kong
Known contact with SARS No No
Likely date(s) of exposure, 2003 Feb 21 Feb 21
Likely setting of exposure Hotel M Hotel M
Date of return to Canada, 2003 Mar 6 Mar 6
Clinical profile
Symptoms and onset, 2003
Malaise Feb 26 Feb 26
Myalgia No Feb 28
Headache Feb 28 Feb 28
Fever Feb 28 Feb. 28
Chills Feb 28 Feb 28
Chest discomfort No No
Cough Mar 1 No
Shortness of breath Mar l No
Nausea No No
Vomiting No No
Diarrhea Mar 7 No
Hospitalized Yes No
Oxygen saturation (%) on room air at 45 NA
admission
Aerosolized medication or nebulizer No No
before isolation
Date of hospital admission Mar 7 NA
No. days after symptom onset that 10
patient was hospitalized
Date of final hospital discharge Jun 12 NA
ICU Yes No
Date of ICU admission Mar 8 NA
Date of ICU discharge May 13 NA
Mechanical ventilation Yes No
Delay to implementation at hospital of:
Respiratory precautions ([dagger]) 15 min ([double NA
dagger])
Negative-pressure isolation 165 min ([double NA
dagger])
Patient characteristics Patient 2 Patient 3
Baseline characteristics
Sex Female Male
Age (y) 64 49
Medical condition Hypertension No
Epidemiologic characteristics
Travel related Yes Yes
City of likely source of SARS Hong Kong Hong Kong
Known contact with SARS Yes No
Likely date(s) of exposure, 2003 Mar 19 Mar 28-30
Likely setting of exposure Dinner party Amoy Gardens
Date of return to Canada, 2003 Mar 20 Mar 30
Clinical profile
Symptoms and onset, 2003
Malaise Mar 24 No
Myalgia Mar 24 Apr 1
Headache Mar 27 Apr 1
Fever Mar 29 Apr 1
Chills Mar 29 No
Chest discomfort Mar 24 No
Cough Mar 29 No
Shortness of breath Mar 29 Apr 3
Nausea Mar 27 No
Vomiting No No
Diarrhea Mar 28 Apr 6
Hospitalized Yes Yes
Oxygen saturation (%) on room air at 80 97; fell to 62
admission within 3 h
Aerosolized medication or nebulizer No No
before isolation
Date of hospital admission Mar 28 Apr 3
No. days after symptom onset that 4 2
patient was hospitalized
Date of final hospital discharge Apr 21 Apr 21
ICU Yes No
Date of ICU admission Apr 1 NA
Date of ICU discharge Apr 18 NA
Mechanical ventilation Yes No
Delay to implementation at hospital of:
Respiratory precautions ([dagger]) Immediate Immediate
([section]) ([section])
Negative-pressure isolation Immediate Immediate
([section]) ([section])
Patient characteristics Patient 4
Baseline characteristics
Sex Female
Age (y) 44
Medical condition No
Epidemiologic characteristics
Travel related No
City of likely source of SARS VCMA
Known contact with SARS Yes
Likely date(s) of exposure, 2003 Mar 29 or Mar 30
Likely setting of exposure Hospital B
Date of return to Canada, 2003 NA
Clinical profile
Symptoms and onset, 2003
Malaise Apr 4
Myalgia Apr 10
Headache Apr 4
Fever Apr 15
Chills No
Chest discomfort No
Cough Apr 11
Shortness of breath Apr 11
Nausea No
Vomiting No
Diarrhea Apr 11
Hospitalized Yes
Oxygen saturation (%) on room air at 86
admission
Aerosolized medication or nebulizer No
before isolation
Date of hospital admission Apr 15
No. days after symptom onset that 11
patient was hospitalized
Date of final hospital discharge May 24
ICU Yes
Date of ICU admission Apr 15
Date of ICU discharge Apr 24
Mechanical ventilation No
Delay to implementation at hospital of:
Respiratory precautions ([dagger]) 7 min
([paragraph])
Negative-pressure isolation 11 min
([paragraph])
* SARS, severe acute respiratory syndrome; VCMA, Vancouver census
metropolitan area; NA, not applicable; ICU, intensive care unit;
ER, emergency room, NPIR, negative-pressure isolation room.
([dagger]) Defined as standard precautions (gloves, gown, eyewear)
plus N95 mask and mask on patient when transported. Full respiratory
precautions also include NPIR.
([double dagger]) Arrived in triage March 7, 2003 1:55 p.m. By
2:10 p.m., admission sheet advises "full respiratory precautions"
be taken. By 2:20 p.m. in single room in ER. Transferred to NPIR
in ER at 4:40 p.m.
([section]) Arrived at hospital masked and admitted directly into
NPIR.
([paragraph]) Arrived in ER on April 14, 2003, at 9:49 p.m.
Identified as suspected SARS patient at 9:56 p.m. Masked and
transferred to NPIR in ER at 10 p.m. Admitted to ICU NPIR on
April 15.
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