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SARS: An Emerging Infectious Disease

SARS: An Emerging Infectious Disease

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SARS: An Emerging Infectious Disease

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  1. SARS: An Emerging Infectious Disease June 11, 2003 Edward L. Goodman, MD

  2. Emerging Infectious Diseases:Institute of Medicine Definition New, reemerging or drug-resistant infections whose incidence in humans has increased within the past two decades….

  3. Major Factors Contributing to EID • Human demographics and behavior • Technology and industry • Economic development and land use • International travel and commerce • Microbial adaptation and change • Breakdown of public health measures

  4. Emerging Infectious Diseases USA 1996 - 2003 • Ebola in non human primates, Texas • Racoon rabies, Ohio • Cyclospora gastroenteritis, multiple states • Non imported Malaria, Georgia and Florida • E coli 0157:H7 in apple juice, multiple states • West Nile Virus 1999, NY and now nationwide • Anthrax 2001; Fla., NYC, DC, NJ • Monkeypox: Prairie Dogs to Humans 2003; Wisc

  5. Goals of today’s presentation • Show the power of epidemiology • Case definition/revisions • Descriptive epidemiology • Geographic Variation • Clinical findings • Infection Control Recommendations • Even before knowing an etiology • Show the extent of modern microbiology • Virology • Gene detection technology • Serology

  6. Epidemiology • The science of studying diseases in populations • Examples • Cholesterol and CAD • Smoking and lung cancer • Tampons and TSS before Staph identified • Defined risk groups for AIDS before HIV identified • Draws conclusions on transmission and control even when etiology not known

  7. Epidemiologic Investigation of an Apparent Outbreak • Preliminary Case Definition • Compare Features of Cases to Non-cases • Refine Case Definition • Case-control studies • Refine Case Definition multiple times • Investigate Etiology in refined definition group • Define Clinical Features • comparing proven to unproven cases

  8. Case Report

  9. Radiology of typical caseLee NEJM 4/7/04

  10. Initial signs of a worldwide outbreak • February 11, 2003 • Respiratory illness in Guangdong province, China • 305 cases, 5 deaths since November 16, 2002 • February 26—March 12, 2003 • Disease spreads to large number of health care workers in Hong Kong and Vietnam • March 12, 2003 • Global alert for Severe Acute Respiratory Syndrome (SARS) • CDC offers assistance to the WHO

  11. Preliminary Case DefinitionMarch 19, 2003

  12. Epidemics Within Epidemics • HIV • Predominantly MSM/IVDU in US and Europe • Predominantly heterosexual in Africa • Lyme Borreliosis • Predominantly joint disease in US • Disproportionately CNS disease in Europe

  13. Epidemics within Epidemics • SARS • Asia and Canada • Healthcare Workers and families • USA • Mostly imported from Asia • Little transmission

  14. The Hong Kong connection:Hotel M February March A B C D E F G H I J K L M Onset of symptoms Stayed at Hotel M

  15. The Hong Kong connection:Hotel M February March A B C D E F G H I J K L M Onset of symptoms Stayed at Hotel M

  16. The Hong Kong connection:Hotel M February March A B C D E F G H I J K L M Onset of symptoms Stayed at Hotel M

  17. Canada 18 HCW F,G F,G 11 close contacts Ireland 0 HCW K K A Hong Kong SAR 95 HCW H,J I, L,M H,J B C,D,E I,L,M >100 close contacts C,D,E B United States 1 HCW Vietnam 37 HCW Singapore 34 HCW 21 close contacts 37 close contacts Spread from Hotel M Reported as of March 28, 2003 Guangdong Province, China A A Hotel MHong Kong

  18. SARS in CanadaPoutenan et al. NEJM May 15, 2003

  19. Timeline linked Candadian cases

  20. SARS in Greater Toronto AreaJAMA June 4, 2003

  21. Epidemic Curve USA May 30363 cases

  22. CDC Update June 4, 2003 • WHO reports 8402 cases from 29 countries • November 1, 2002 – June 4, 2003 • 772 deaths (9.2% CFR) • US and PR Cases 373, no deaths • 67 probable, 306 suspect • 65/67 attributed to international travel • One each HCW and household contact

  23. Finding the Pathogen • Pathology • Virology • Gene detection • Classification • Diagnostics

  24. What are Coronaviruses? • Taxonomy • Order Nidovirales • Family Coronaviridiae • Genus Coronavirus • Structure: large, enveloped, positive-stranded RNA • Genome: 30,000 nucleotides, the largest of any RNA virus

  25. Structure

  26. More than you want to know! • Group 1 and 2 are mammalian • Group 3 are avian • Major veterinarian pathogens • Infectious bronchitis virus • Feline infectious peritonitis virus • Transmissible gastroenteritis virus

  27. Enough already! • Human coronavirus infections • Group 1 and 2 • 30% of common cold viruses • SARS human coronavirus (SARS-CoV) • Urbani strain, named after Italian physician who succumbed to this virus • Distinct from other CoV

  28. Relatedness to other Coronaviruses

  29. Clinical Aspects of Severe Acute Respiratory Syndrome (SARS) • Incubation period 2-10 days • Onset of fever, chills/rigors, headache, myalgias, malaise • Respiratory symptoms often begin 3-7 days after symptom onset

  30. Symptoms Commonly Reported By Patients with SARS1-5 Symptom Range (%) Fever 100 Cough 57-100 Dyspnea 20-100 Chills/Rigor 73-90 Myalgias 20-83 Headache 20-70 Diarrhea 10-67 1. Unpublished data, CDC. 2. Poutanen SM, et al. NEJM 3/31/03. 3. Tsang KW, et al. NEJM. 3/31/03 4. Peiris JSM, et al. Lancet 4/8/03 5. Lee N. et al NEJM 4/7/03

  31. Symptoms Reported by Patients With Diagnostic SARS-CoV Laboratory Testing, United States, 2003 *p=.07

  32. Common Clinical Findings in Patients with SARS1-5 1. Unpublished data, CDC. 2. Booth CM, et al. JAMA 5/6/03. 3. Tsang KW, et al. NEJM. 3/31/03 4. Peiris JSM, et al. Lancet 4/8/03 5. Lee N. et al NEJM 4/7/03

  33. Clinical Findings in Patients With Diagnostic SARS-CoV Laboratory Testing, United States, 2003 *p<.05

  34. Radiographic Features of SARS • Infiltrates present on chest radiographs in > 80% of cases • Infiltrates • initially focal in 50-75% • interstitial • Most progress to involve multiple lobes, bilateral involvement

  35. Lee N. et al NEJM 4/7/03

  36. Lee N. et al NEJM 4/7/03

  37. Clinical Outcome of Patients with SARS, 2003 1. Unpublished data, CDC. 2. Booth CM SM, et al. JAMA 5/6/03. 3. Tsang KW, et al. NEJM. 3/31/03 4. Peiris JSM, et al. Lancet 4/8/03 5. Lee N. et al NEJM 4/7/03

  38. Clinical Outcome of Probable SARS Cases*, 2003 * http://www.who.int/csr/sarscountry/2003_05_07/en/

  39. Clinical Features Associated with Severe Disease • Older Age • Underlying illness • ? Lactate dehydrogenase levels • ? Severe lymphopenia

  40. Transmission • Probable major modes of transmission • Large droplet aerosolization • Contact • Direct • Fomite • Airborne transmission cannot be ruled out • ? Role of aerosol-generating procedures • ? Fecal-oral • Transmission efficiency may vary among individuals