1 / 35

Severe Acute Respiratory Syndrome (SARS)

Severe Acute Respiratory Syndrome (SARS) . Lydia Ho & Rui Yang BISC 209 Professor Mary Allen. November 16, 02 Initial cases of SARS appeared in South China. February 14, 03 305 cases & 5 deaths from an unknown acute respiratory syndrome. March 03:

fran
Télécharger la présentation

Severe Acute Respiratory Syndrome (SARS)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Severe Acute Respiratory Syndrome (SARS) Lydia Ho & Rui Yang BISC 209 Professor Mary Allen

  2. November 16, 02 Initial cases of SARS appeared in South China • February 14, 03 • 305 cases & 5 deaths from an unknown acute respiratory syndrome

  3. March 03: New reports of outbreaks came in from Hong Kong, Singapore & Vietnam New syndrome was designated as “severe acute respiratory syndrome,” or SARS

  4. March 12, 03: WHO issued global alert about SARS March 17, 03: WHO called for global collaborative research on SARS

  5. March 24, 03: Scientists in CDC and HK announced isolation of new coronavirus from SARS patients DNA sequencing shows this virus is distinct from all known human pathogens

  6. April 20-25, 03: • Outbreaks in Hanoi, Hong Kong, China, Singapore & Toronto showed signs of peaking April 25, 03: Nearly 3000 SARS cases have been identified in China City closed down schools & imposes strict quarantinemeasures

  7. By the end of June, 03: Most countries were removed from the list of areas with recent local transmission of SARS: • Singapore, Hong Kong, Beijing , Toronto , Taiwan But the investigation continues…

  8. The Pathogen behind it all… SARS-CoV Virus

  9. Discovery of the new virus • Kochs postulates • Discovery of novel coronavirus in patient • Isolation of cell culture • Reproducible symptom in cell culture • Identical isolates produced Novel coronavirus is the cause of SARS

  10. Coronaviridae • A family of large, enveloped, positive-sense single stranded RNA virus • Irregular shape • Characteristic ‘club-shaped’ surface projections (~20nm)

  11. SARS-CoV Genome • 71% of the genome codes for polyproteins • Remainder: codes for structural proteins • S (spike): receptor binding, cell fusion, major antigen • E (envelop): envelop-associated protein • M (membrane): transmembrane-budding • N (nucleocapsid): genome-associated phosphoprotein

  12. SARS-CoV Genome

  13. SARS-CoV Life Cycle • S-protein binds to receptor  initiation of induced endocytosis • Translation of viral RNA polymerase • Transcription of (+) RNA into genomic and subgenomic mRNA in the cytoplasm • N protein synthesized from free ribosome • S and M protein synthesized in RER • Budding from RER as virion, excretion from cell via Golgi

  14. SARS Case Definition

  15. Clinical Symptoms High fever

  16. Clinical History • 10 days before onset of symptoms • Close contact with probable/suspected SARS patients • Live in / travel to area with transmission of SARS

  17. Transmission of SARS

  18. Transmission of SARS-CoV • Highly probable: origination is a cross-species jump from civet cat to human • Human-to-human transmission • Direct contact • Spread in droplets shed from respiratory secretions • Possible fecal transmission

  19. Infectiousness of SARS • Debatable • Most patients are moderately infectious • Cases of “superspreaders” reported • Factors affecting infectiousness are • Viral load of the secretion from index patient • Aerosol-generation procedures • Distance of the index patient

  20. Methods of Diagnosis

  21. Virus Detection • Virus isolation: inoculate suitable cell culture with patient specimens

  22. Antibody Detection When infected by SARS-CoV  antibodies (e.g. IgM and IgG) are produced / change in level • Enzyme-linked immunosorbent assay (ELISA)

  23. Antibody Detection • Immunofluorescence assay (IFA): • Sample: patient serum • Method: • Fix SARS-CoV-infected cells on microscope’s slide (patient antibodies already bound to viral antigens) • Immunofluorescent-labeled 2º antibodies bind to human IgG/IgM • Significance: positive result after 10 days of onset of illness

  24. Clinical Findings • Clinical history & observation • Chest radiography: important role • 70-80% patients have abnormal chest radiographs SARS patient Normal

  25. Method of Cure

  26. Immunomodulatory therapy • Corticosteroid • Very powerful: affect entire body • Anti-inflammatory & immunosuppressive effects • Significance: early improvement of fever, better radiographic infiltrates • Controversy: • ? Effectiveness • Adverse side effects

  27. Antiviral Agents • Ribavirin: nucleoside analog • Most frequently administered • Have antiviral activity against many DNA & RNA viruses • Criticism: • ? Effectiveness • Adverse side effects

  28. Antiviral Agents • Protease inhibitor: • Lopinavir-ritonavir co-formulation: protease inhibitor used to treat HIV infection • With ribavirin: block processing of the viral replicase polyprotein  prevent RNA replication

  29. Method of Prevention & Control

  30. Principle of Disease Confinement • Principle: to break the chain of transmission from infected to healthy person • 3-step protocol of disease confinement • Case detection • Prompt isolation • Contract tracing • Daily health check • Voluntary home isolation

  31. Epidemic Containment • Creation of emergency operating center • Institutional support • Efficient quarantine measures • Legislation • International collaboration—WHO • Travel alerts and restrictions • Coordination for research • Agreement of countries on containment protocol

  32. SARS and Beyond… The early management of SARS epidermic may serve as a model for the containment of future epidermics and pandemics

  33. References Cann, A. (January 20, 2004). Severe acute respiratory syndrome (SARS). Retrieved from: http://www-micro.msb.le.ac.uk/3035/coronaviruses.html Dept. of Communicable Disease Surveillance and Response, WHO. (2003). Consensus document on the epidemiology of severe acute respiratory syndrome (SARS). Kamps, Hoffmann. (October, 2003). SARS Reference. Retrieved from: www.SARSreference.com Shanghai Center for Bioinfomatics Technology. (2004). Life cycle of the SARS virus. Retrieved from: http://www.scbit.org/english/sars/Life%20cycle%20of%20SARS%20virus.htm Siddell, S, Wege H., ter Meulen V. The biology of coronaviruses. J. Gen Virol. 1983; 64 (Pt4): 761-776 Thiel, et al. (June 19, 2003). Mechanisms and enzymes involved in SARS coronavirus genome expression, Journal of general virology. Retrieved from: http://www.socgenmicrobiol.org.uk/JGVDirect/19424/19424ft.htm Tsang KW, Ho PL, Ooi GC, Yee WK, et al. A Cluster of Cases of Severe Acute Respiratory Syndrome in Hong Kong. N Engl J Med 2003, 348:1977-85. http://SARSReference.com/lit.php?id=12671062 World Health Organization. (2004). Case Definition. Retrieved from: www.who.int/csr/sars/casedefinition/en/ World Health Organization. (2004). Diagnostic Tests. Retrieved from www.who.int/csr/sars/diagnostictests/en/

More Related