Public Health Perspective on SARS Diagnostics

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Public Health Perspective on SARS Diagnostics

• Stephen M. Ostroff
• Deputy Director
• National Center for Infectious Diseases, CDC

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Outline

• International Domestic Experience with SARS
• Public health imperatives for SARS diagnostics

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SARS Case Definitions (USA)

• Clinical Criteria
• Fever (gt38 C) respiratory illness
• Radiologic findings (pneumonia, RDS)
• Autopsy findings (pneumonia, RDS)
• Epidemiologic Criteria
• Travel history (10 days) to SARS-affected area
• Close contact with known or suspected SARS
  patient
• Laboratory Criteria
• Antibody to SARS-coV (acute or gt28 days)
• SARS-coV RNA by RT-PCR 2nd PCR assay
• Virus isolation

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SARS Case Definitions (USA)

• Suspect
• Clinical epidemiology criteria
• Probable
• Clinical epidemiology criteria plus radiologic
  or autopsy evidence of pneumonia/RDS
• Confirmed
• Positive serology, PCR (x2), culture

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US SARS Situation

• gt17,000 individual reports received
• 423 persons met case definition
• 348 (80) suspected cases
• 75 (20) probable cases

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SARS Case Demographics

• Factor Suspect Cases Probable Cases
• Age group
• lt18 22 22
• 18-64 72 56
• 65 6 21
• Male/female 53/47 53/47
• Race/ethnicity
• White 61 48
• Asian 36 49
• Hospitalized gt1 day 24 61

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Number of Probable and Suspect SARS Cases by
Date of Illness Onset, United States, 2003 N
423
Includes 5 suspect/probable cases with illness
onset before 2/1/03 data reported through July
10, 2003.
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U.S. Probable SARS Cases
N 75
2
3
10
2
CT 3MA 2MD 0NJ 1
1
1
2
1
3
4
24
2
1
1
1
1
1
1
1
1
4
HI 2
Data as of 6/18/03
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U.S. Probable SARS CasesN 75

• 73 (97) reported travel to areas with documented
  or suspected community transmission of SARS
  within the 10 days before illness onset
• 1 (1) HCW caring for SARS patient
• 1 (1) household contact of SARS patient

Data as of 6/18/03
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SARS Lab Specimens Received at CDC (as of
7/9/03)

• Specimen Type No. Specimen Type
  No.
• Autopsy tissue 105 Stool 344
• BAL/tracheal asp. 31 Urine
  224
• NP Swab Serum
• acute 546 acute 1,535
• convalescent 73 convalescent
  530
• unknown 225 unknown 1,420
• Sputum 325 Other 80
• Throat wash/swab 141 TOTAL
  5,579

Includes both domestic international
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Diagnostic Findings

• Test No. Tested No. () Pos.
• Coronavirus
• Serology 2,742 188 (7)
• RT-PCR 1,235 44 (4)
• HMPV
• RT-PCR 218 21 (10)

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SARS-CoV Antibody TestingInterpretable Results
United States, 2003
Type of Case CoV Probable 8/45
(18) Suspect 0/138 (0)
Data through 6/20/03
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SARS-CoV Cases United States, 2003N 8

• 7 reported travel
• 4 reported travel to Hong Kong
• 2 reported travel to Toronto
• 1 reported travel to both Singapore and Taiwan
• 1 spouse of lab-confirmed SARS patient who had
  traveled to Hong Kong

defined as travel to areas with documented or
suspected community transmission of SARS within
the 10 days before illness onset
MMWR 200352570.
Data through 6/18/03
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Why do we need availability of good SARS
diagnostic tests for public health purposes?
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Public Health Rationale

• Appropriate clinical management
• Current
• Future (therapeutics and prophylaxis)
• Disease surveillance

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Respiratory Tract Infections in Travelers

• gt600 million persons travel annually
• gt25 develop respiratory symptoms during travel
  10 following travel
• 10-20 develop acute respiratory infection
• Returning travelers seeking health care
• 7.8 present with ARI (2 complaint)
• Travel to east Asia associated with ARI (OR 1.26
  95 CI 1.01-1.57)

Leder, et al CID 2003399-406
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Public Health Rationale

• Public health control measures
• Hospital in- and out-patient management

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Institutional Quarantine
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Public Health Rationale

• Public health control measures
• Community-based isolation quarantine

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Community Controls

• Cordon Sanitaire

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430pm July 11, 2003 Initial test results
negative DYESS AIR FORCE BASE, ABILENE, Texas
The initial test results from the laboratory
samples taken from eight Dyess Air Force Base
members that may have been exposed to Sudden
Acute Respiratory Syndrome are negative for the
virus, according to health professionals with the
7th Medical Group at Dyess Air Force Base.Of
the first samples that were sent to an Air Force
lab and the Center for Disease Control and
Prevention (CDC) for testing, two were positive
for a common infectious bacteria known as
Streptococcus pneumoniae, often seen in patients
with pneumonia.Although the early samples are
negative for SARS coronavirus, more testing is
being conducted to rule out infection. Definitive
results may not be in for another two to three
weeks.So far, 10 people associated with Dyess
Air Force Base have now been identified and
isolated in their homes for possible SARS
infection.All are currently stable or improving
as of this morning. They remain isolated in their
homes and have been instructed to stay there
until released. CDC guidelines recommend release
10 days past the date of fever and respiratory
symptoms.
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Public Health Rationale

• Public health control measures
• Contact tracing and testing
• Epidemiologic investigations
• Environmental/product sampling
• Evaluation of viral shedding
• Blood supply
• Screening

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Additional issues

• SARS co-factors (HMPV, chlamydia)
• Need to know it is SARS
• Need to know it is something else
• Ideal would be a multiplexed assay