1. By: Swarali S Tadwalkar
PHC 6002: Infectious Disease Epidemiology
Instructor: Dr Aurora Sanchez-Anguiano
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Image source: http://www.healthytravelblog.com/2012/09/25/the-return-of-sars/
http://bloomberg.nursing.utoronto.ca/news/teaching-in-a-time-of-crisis-sars-and-the-impact-on-u-of-ts-faculty-of-nursing

2. *
*Viral Respiratory Disease caused by SARS-CoV (SARS
Coronavirus)
*Highly contagious atypical pneumonia
*First reported in February 2003 in Asia through a major
outbreak
*Importance:
*CDC declared SARS-CoV as a select agent in 2012 meaning it has
the potential to pose severe threat to public health and safety
*High transmissibility
*First important infectious disease of the new millenium
*Infection to HCW – Major concern

3. *Etiologic Agent: SARS Coronavirus (SARS-CoV)
*Transmission: Primarily through droplet infection
*Other sources: Surface contamination and Air-borne
*Natural History: Acute viral infection of respiratory tract
*Viral dynamics not clear though high viral load seen in lower
respiratory tract
*Low load in upper respiratory tract and feces in the first 4
days but peaks at approximately 10 days
*High infectivity at febrile stage
*Life-cycle: RNA virus of coronaviridae family
*Important stages: Replication and Transcription
*Replication involves synthesis of full-length negative strand
*Discontinuous Transcription process not fully understood
*
Image source: https://socioecohistory.wordpress.com/2012/09/27/new-sars-virus-attacks-arabs-created-by-israeli-and-british-bio-weapons-lab/

4. *
*Pathophysiology: Complex processes leading to degradation of organs
*Primary target - lungs and intestines (epithelial cells, villi, alveoli)
*Immune system - severe lymphocyte depletion
*Clinical Features: Incubation period is 2-10 days
*Fever, Myalgia, headaches, dry non-productive cough
*Others: Diarrhea (25%), shortness of breath, hypoxemia
*Diagnosis: Chest radiography, pulse oximetry, blood cultures, sputum
Gram stain and culture, and testing for other respiratory pathogens
*Treatment: Supportive care, infection control measures and broad
spectrum antibiotics including fluoroquinolone and macrolide
*Complications: Risk of co-infections, comorbities, respiratory failure
*Prognosis: Can lead to serious medical complications
* May require hospitalization, Intubation or ventilator support

5. *
*Primary Reservoir = Human
*Other animal reservoirs for coronaviridae family viruses include cats,
pigs, chicken, rats and mice
*Infections include respiratory or enteric manifestations
*Person
*Total deaths = 774 out of 8,098 affected as per WHO
*Canada: Median reported age of death was 75 years
*Peoples’ Republic of China: 71.9% deaths were above 60 years of age
*HongKong, China: 52% deaths were amongst above 65 years olds
*Sex preference: Some studies report higher female CFR while some
report vice versa
*Racial preference has not been documented though outbreak was
restricted to about two dozen countries alone
*Greater transmission and infectivity was seen among Health care
workers perhaps due to exposure to higher viral load

6. *
*Major outbreak in 2003
*No outbreak of SARS seen after that though other forms
such as MERS (Middle East Respiratory Syndrome) seen
*Time: No seasonal pattern
*Total incubation period: 1-14 days
*Median incubation period: 4-5 days with mean of 4-6 days
*Epidemic curve
*Person-to-person propagation
*Peaks of different heights
*Onset of outbreak: Nov 2002
*Global alert: March 15, 2003,WHO
Adapted from World Health Organization. Epidemic curves – Severe Acute Respiratory Disease (SARS)
http://www.who.int/csr/sars/epicurve/epiindex/en/index1.html

7. *
*Place: About couple of dozen countries were affected
*Most cases occurred in:
*China
*Phillippines
*Vietnam
*Singapore
*Canada
*USA
*Some parts of Europe
*Only 8 cases were seen in US of which almost all had
travelled to other parts of the world
Image Source: Boulos International Journal of Health Geographics 2004 3:2 doi:10.1186/1476-072X-3-2

8. *
*Intrinsic factors:
*Genetically, HLA (Human Leukocyte Antigen) was identified to
be correlated to SARS susceptibility
*Age of the patient: Higher incidence was seen amongst older
age group (> 60 years)
*Sex of the patient: Males were more likely to be affected
however, amongst HCWs more females were affected
*Children and pregnant women were considered to be at higher
risk
*Higher mortality was seen amongst patients with comorbidities
such as diabetes, heart diseases etc
*Variation in host response to infection

9. *
*Extrinsic Factors
*Pathogenic virus: SARS Coronavirus
*Person-to-person contact: Droplet and Air transmission
*Led to higher transmittance to HCWs and spread of disease to
others in population
*Air travel: Led to spread of disease from China to Canada due
to travel of infected patients/carriers
*Lack of infection control measures leading to higher
transmission in health care settings
*Lack of maintenance of hygienic conditions
*Influence of diet or other lifestyle factors were not identified as
major risk factors during the outbreak. However, they may
have caused variability in susceptibility and immune response
of host

10. *
*Concern: Insufficiency of vaccine due to new strain
*Global Alert issued by WHO in March 2003
*Monitoring passengers and crew traveling by air
*Quarantine of infected patients
*Avoiding mass gatherings and activities
* Infection control measures
*Preventing person-to-person contact (using masks)
*Handwashing
*Safety precautions by HCWs in healthcare settings
*Extra precaution during intubation and intensive care to avoid
exposure to high viral loads
*Surveillance and timely reporting
*Monitoring fever and cough symptoms amongst children and
adults every few hours in schools, offices and other institutions

11. *
*Study by Raboud et. Al (2010)
*One of the most extensive epidemiological studies in health-care
settings in Ontario, Canada
*Merits: Detailed inclusion/exclusion criteria, extensive statistical
analysis
*Demerits: Retrospective nature may have led to recall bias in the
study, biological variability may have been a source of
confounding
*Donnely et. al (2003)
*Assessed epidemiology of SARS in Hong Kong, China
*Result: Patient’s age was strongly associated with outcome
*Merits: Detailed study design and methods, inclusion/exclusion
criteria, large sample-size
*Demerits: Non-stratification by sex, less information on other
factors and self-reporting of information

12. *
*Other coronavirus disease forms witnessed: MERS (Middle
East Respiratory Syndrome)
*Concern over mutant forms of viral strains making it
difficult to determine diagnosis and treatment
*During 2003 SARS outbreak, treatment could not be easily
determined making it difficult to treat patients and preventing
spread
*Protective efficacy of vaccines still under scrutiny
*Research with novel ideas to manage diseases required
*DNA vaccine could potentially prevent proliferation of RNA
virus by hindering replication

13. *
* CDC/NCIRD. (2004). Basic Information about SARS. CDC/NCIRD.
* Chan, H. L., Tsui, S. K., & Sung, J. J. (2003). Coronavirus in severe acute
respiratory syndrome (SARS). TRENDS in Molecular Medicine, 9: 323-325.
* Donnelly, C. A., Ghani, A. C., Leung, G. M., Hedley, A. J., Fraser, C., Riley, S.,
et al. (2003). Epidemiological determinants of spread of causal agent of severe
acute respiratory syndrome in Hong Kong. The Lancet, 1-6.
* Gu, J., & Korteweg, C. (2007). Pathology and Pathogenesis of Severe Acute
Respiratory Syndrome. The American Journal of Pathology, 170:1136–1147; DOI:
10.2353/ajpath.2007.061088.
* Ng, M., Cheng, S., Lau, K., Leung, G., Khoo, U., Zee, B., et al. (2010).
Immunogenetics in SARS: a case control study. Hong Kong Medical Journal,
16(Suppl 4):S29-33.
* Raboud J, Shigayeva A, McGeer A, Bontovics E, Chapman M, et al. (2010) Risk
Factors for SARS Transmission from Patients Requiring Intubation: A
Multicentre Investigation in Toronto, Canada. PLoS ONE 5(5): e10717.
doi:10.1371/journal.pone.0010717
* Sampathkumar, P., Temesgen, Z., Smith, T. F., & Thompson, R. L. (2003).
SARS: Epidemiology, Clinical Presentation, Management, and Infection
Control Measures. Mayo Clinic Proceedings, 78:882-890.
* SARS Epidemiology Working Group, W. (2003). Consensus Document on the
Epidemiology of SARS. WHO.

14. *Any questions??
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