Severe Acute Respiratory Syndrome

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Contents 1 Etiology 2 Epidemiology 3 Pathology 4 Genetics 5 Clinical-manifestations 6 Laboratory 7 Radiology 8 Differential-diagnosis 9 Management 10 More General Terms 11 Additional Terms 12 References

Etiology

• coronavirus
• a new metapneumovirus may be involved [2]

Epidemiology

• Winter 2003 epidemic reported to CDC &

• China (Guangdong Province), Hong Kong, & Hanoi, Viet Nam
• world-wide 3169 cases; 144 <A24393>deaths</A24393> as of April 17, 2003

• areas with <A546>transmission</A546> of SARS (as of 3-17-03):

• Hong Kong & Guangdong Province, People's Republic of China
• Hanoi, Vietnam
• Singapore
• Toronto, Canada.

• transmitted by:

• <A24003>respiratory</A24003> <A9161>secretions</A9161> &/or <A24351>body fluids</A24351>
• contaminated hands or <A2911>fomites</A2911> [4]
• stable in <A13601>stool</A13601> & urine for 4 days [4]

• stable for 24 hours - 4 days on toilet seats [4]
• less <A1721>contagious</A1721> than <A11644>influenza</A11644>, but more <A1721>contagious</A1721> than <A19920>HIV</A19920> [10]
• resevoir in China is horsehoe <A26892>bats</A26892> [14]
• <A2382>healthcare workers</A2382> at high risk [11]

• 2/3 of cases occur with exposure when <A8668>SARS</A8668> unsuspected
• <A3001>infection control</A3001> measures effective when enforced

• children & adoloscents tend to have less severe disease than adults
• the tracks <A8668>SARS</A8668> cases [12]

Pathology

• open lung biopsy shows interstitial inflammation [10]
• microscopic Pathology (lung): [6]

• diffuse alveolar damage (DAD) in varying phases of organization
• hyaline membranes in alveolar walls
• multinucleated atypical epithelial cells & organizing exudate within alveolar spaces d acute bronchopneumonia
• variable intravascular thrombosis

• receptor for SARS coronavirus is ACE2 ( angiotensin-converting enzyme-2)

Genetics

• mutation has resulted in two strains of SARS [3]

Clinical-manifestations

• incubation period: up to 1-16 days ( mean 5-6 days)
• influenza-like symptoms (early)

• fever (100%) & malaise (70%) are followed by dry cough (100%) & dyspnea (80%)
• muscle aches, headache
• sore throat & rhinorrhea (<25%)
• see differentiating SARS from influenza

• crackles at lung bases on chest auscultation
• dullness to percussion a lung bases [13]
• more severe manifestations may follow:

• hypoxia, pneumonia, acute respiratory distress
• mechanical ventilation may be required (10-20%) [9]
• death (5%)

• close contacts, including healthcare workers, may develop a similar illnesses within 10 days
• case definition - [8]
• triphasic pattern [13]

• improvement, but persistent flu-like symptoms in 1st week
• deterioration in 2nd week
• worsening between days 10 & 15, coinciding with appearance of antibodies against the causative coronavirus

Laboratory

• complete blood count ( CBC)

• leukopenia, lymphopenia, thrombocytopenia

• increased ALT, AST, LDH [10]
• increased creatine kinase [10]
• pulse oximetry: diminished oxygen saturation (50%)
• serology:

• rising antibody titers to SARS coronavirus
• antibodies appear in plasma between days 1-15 [13]

Radiology

• chest X-ray:

• consolidation predominantly in lower lung fields, increasing in size over seveal days [10]
• pleural effusions have not been observed

Differential-diagnosis

• acute respiratory distress syndrome
• pneumonia
• influenza

Management

• In ambulatory settings, immediately place the patient in a private room, place a surgical mask on the patient & the door closed
• If the patient is being evaluated in the EMC or already has been admitted, the patient should be placed in a negative- pressure isolation room or private room with a portable HEPA filtration unit
• Call UCLA Westwood Hospital Epidemiology at 825-9146 & the UCLA Westwood Page Operator at 825-6301 for the Adult or Pediatric Infectious Disease physician on call.
• Isolation Precautions:

• Traffic: Minimize the number of people who enter the room, including staff & visitors; keep the room door closed
• Respirators: wear a disposable N-95 respirator (e.g., Teknol TB mask) or, if not available, wear a surgical mask when entering the room & remove after leaving the room
• Facial Shields or Eye Protectors: Wear a face shield or eye protectors with side shields when entering the room & remove after leaving the room
• Gowns: Wear a disposable yellow gown when entering the room & remove when after the room
• Gloves: Wear disposable gloves when entering the room & remove after leaving the room
• Hand hygiene: Wash hands with soap & water or alcohol- based hand rub before & after any patient contact, including touching surfaces or items in the immediate vicinity of the patient

• No specific antiviral therapy has been proven effective [1]

• ribavirin plus steroids may be useful [10]
• oseltamivir may be useful [10]

• prognosis: [2]

• most patients recover
• 10-20% require mechanical ventilation
• varies with age [13]

• overall mortality 5% [5]; 9.6% () [13]
• disease mild in young children
• mortality of > 40% in older adults (> 60 years) in one study

• <A3702>CDC</A3702> & recommend that persons planning non-essential travel to at risk areas in the Far East should consider delaying or deferring the trip

More General Terms

• viral infection
• lung disease
• syndrome

Additional Terms

• differentiating SARS from influenza
• seryl-tRNA synthetase (serine-tRNA ligase, SerRS, SARS)

References

1. David A. Pegues, M.D. Associate Clinical Professor, Hospital Epidemiologist Division of Infectious Diseases, 37-121 CHS David Geffen School of Medicine at UCLA Los Angeles, CA 90095-1688 phone 310-825-2465, facsimile 310-825-3632 email dpegues@mednet.ucla.edu
2. Prescriber's Letter 10(4):23-24 2003 Prescriber's Letter 10(5):25 2003 [1]
3. CNN News 05/02/03
4. Washington Post/World Health Organization 05/03 [2]
5. Armed Forces Institute of Pathology [3]
6. url>http://www.afip.org/Departments/Pulmonary/SARS/pathogen1b.html</url>
7. WHO guidlines [4]
8. url>http://www.who.int/csr/sars/casedefinition/en/</url>
9. url>http://www.who.int/csr/sars/clinical/en/</url>
10. Journal Watch 23(9):69, 2003 [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
11. Journal Watch 23(23):187, 2003 Ho AS et al, Ann Intern Med 139:564, 2003 <PubMed> PMID: [15]
12. Internet> [16]
13. Journal Watch 24(1):4, 2004
14. Lau SK, Woo PC, Li KS, Huang Y, Tsoi HW, Wong BH, Wong SS, Leung SY, Chan KH, Yuen KY. Severe acute respiratory syndrome coronavirus-like virus in Chinese horseshoe bats. Proc Natl Acad Sci U S A. 2005 Sep 27;102(39):14040-5. Epub 2005 Sep 16. PMID: [17]
    - Li W, Shi Z, Yu M, Ren W, Smith C, Epstein JH, Wang H, Crameri G, Hu Z, Zhang H, Zhang J, McEachern J, Field H, Daszak P, Eaton BT, Zhang S, Wang LF. Bats are natural reservoirs of SARS-like coronaviruses. Science. 2005 Oct 28;310(5748):676-9. Epub 2005 Sep 29. PMID: [18]
15. Severe Acute Respiratory Syndrome: NIH Institute and Center Resources [19]
16. National Guideline Clearinghouse
    - Public health guidance for community-level preparedness and response to severe acute respiratory syndrome (SARS). Version 3. Supplement E: managing international travel-related transmission risk. ngc-guideline: [20]
    - Management guidelines for obstetric patients and neonates born to mothers with suspected or probable severe acute respiratory syndrome (SARS). Society of Obstetricians and Gynaecologists of Canada ngc-guideline: [21]

Severe Acute Respiratory Syndrome (SARS)