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Transcript of SARS-The Toronto Experience - · PDF fileSARS-The Toronto Experience ... Notes: 1The number of...
SARS-The Toronto Experience
Lecture given at the 13th ECCMID 2003 on May 11th byProf. Donald E. Low
Department of MicrobiologyUniversity Health Network, Mount Sinai Hospital and
University of TorontoToronto, Ontario, Canada
The Outbreak
Index Case Case A(Mother) (Son)
• A ProMED-mail post
• Source: WHO Press Release 12 Mar 2003• Acute respiratory syndrome in Hong Kong SAR, Viet
Nam• ---------------------------------------------• WHO issues a global alert about cases of atypical
pneumonia• Cases of severe respiratory illness may spread to
hospital staff• Since mid February 2003, WHO has been actively
working to confirm reports of outbreaks of a severe form of pneumonia in Viet Nam, Hong Kong SAR, China, & Guangdong province in China.
Index Case Case A(Mother) (Son)
March 13th, 2003
• That morning:– phone call from physician at Scarborough Grace
Hospital (SGH) regarding an unusual cluster of unexplained illnesses in a Chinese family including two deaths
• That evening:– 4 family members assessed and admitted at
Mount Sinai Hospital with pneumonia
Index Case Case A(Mother) (Son)
(Son)
(Father) (Son) (Daughter-in-law)
Index Case Case A
Case B
(Mother) (Son)
Index Case Case A
Case B
Case B’swife
24 persons
(Mother) (Son)
9 persons
Index Case Case A
Case B
Case C
Case B’swife
9 persons
24 persons
21 persons
(Mother) (Son)
Index Case Case A
Case B
Case C
Case B’swife
9 persons
24 persons
21 persons
Case D
15 persons
7 persons
(Mother) (Son)
Case A(died)
Case B(died)
Case C(died)
4 members of family A
Family A’sphysician 1 CC
1 X-ray tech
3 ICU nurses
1 HH
3HH
3 EMS
March 16, 20037 ER visitors1 ER patient
5 HH1 CC
6 CCU nurses
3 HH1 CCU Clerk
1 physician1 physician’s clerk
3 HH
1 CCU patient( 1 died)
Transferred toanother hospital
1 physician
1 HH
Figure 3. Transmission of SARS in Hospital A (N=72)
2 ER nurses 2 ER nurses
1 ER Clerk
Case B’s wife(died)
4 ER nurses Clinic nurse
1 Housekeeper
1 HH
1 Housekeeper
1 EMS
LEGEND
Case
Household case
Close contact case
Transmission outsideof Hospital A
HH
Transferred toHospital B
Index Case(died)
Case C’s wife
1 coworker privatesector
CC
1 visitor1 ER patient
10HCW, 3V,2P
7 HCW
Transmission of SARS in hospital C (N=7)
Reported cases of SARS in cases linked to the BLD group March 20 to April 16, 2003
0
1
2
3
4
5
6
7
8
19/03
/0321
/03/03
23/03
/0325
/03/03
27/03
/0329
/03/03
31/03
/0302
/04/03
04/04
/0306
/04/03
08/04
/0310
/04/03
12/04
/0314
/04/03
16/04
/03
Date of onset of symptoms
Num
ber o
f cas
es
Health Care WorkerBLDFamily
Clinical Disease
Clinical Features and Short-term Outcomes of 144 Patients
With SARS in the Greater Toronto Area
(Booth et al. JAMA express)
DemographicsStudy population 1471
Median age 45 yrs (range 17-99)Female 88 (61%)Male 56 (39%)
Health care worker 73 (51%)Nurse 29 (40%)Physician 14 (19%)Other 30 (41%)
1Note: 3 patients contracted SARS while admitted to hospital for other conditions, they have been excluded from the subsequent analysis
Co-MorbiditiesDiabetes 16/144 (11%)COPD 2/144 (1%)Chronic renal failure 2/144 (1%)Cancer 9/144 (6%)Cardiac disease 12/144 (8%)
ExposureTravel 3 (2.1%)Home 35 (24%)Hospital1 111 (77%)
Hospital A 82 (74%)Hospital B 8 (7%)Hospital C 7 (6%)Other 14 (13%)
*Note: 1This group includes healthcare workers, patients and visitors.
Time from Exposure to Symptoms
Median days from earliest known exposure1
“Prodrome”2 6 days (3-10)3
Fever 7 days (4-10) Diarrhea 8 days (3-11)Cough/Dyspnea 9 days (5-12)
Notes: 1The number of days is based on history from the patient.2”Prodrome” includes headache, malaise, myalgia.325th and 75th percentiles are shown in parentheses.
Course of IllnessInitial symptoms of SARS:
“Prodrome”1 and Fever 33 (23%)Fever alone 33 (23%)“Prodrome” alone 19 (13%)“Prodrome”, fever, and cough 16 (11%)Fever and cough 15 (11%)Cough alone 13 (9%)
Note: 1”Prodrome” includes headache, malaise, myalgia.
Course of Illness:another view
How often is: “prodrome” first? 74 (52%)fever first? 106 (74%)cough first? 51 (35%)diarrhea first? 9 (6%)
Course of IllnessSeen prior to admission 49 (34%)
ER 23 (52%)Clinic/Doctor’s office 18 (41%)Hospital 3 (7%)
Median time from first visit until admission 3 days (2-5)1
Note: 125th and 75th percentiles are shown in parentheses
RhinorrheaAbd. PainDizziness
Prod. CoughChest Pain
ArthralgiaSore Throat
Nausea/VomitDiarrhea
ChillsMalaise
HeadacheDyspneaMyalgia
Nonprod. CoughReported Fever
0 20 40 60 80 100
Percent with Symptom At Presentation
0 20 40 60 80 100
2.1%3.5%4.2%4.9%
10.4%10.4%
12.5%19.4%
23.6%27.8%
31.2%35.4%
41.7%49.3%
69.4%99.3%
Physical FindingsTachycardia (>100bpm) 66 (46%)
Tachypnea (RR>20) 53 (37%)
Rales 37 (26%)
Chest Radiograph Findings
At admission Progression during hospitalization
Normal 36 (25%) No change 15/36 (42%)
Unilateral 12/36 (33%)
Bilateral 9/36 (25%)
Unilateral infiltrate 66 (46%) No change 42/66 (64%)
Bilateral 24/66 (36%)
Bilateral infiltrate 42 (29%) - -
Pneumothorax 4 (3%)
Laboratory Indices: Admission
Median Value (25 th, 75thPercentile) Normal range
WBC 5.2 x 10 9 /L (3.6 -7.3) 4-11
Neutrophils 3.6 x 10 9 /L (2.4 -5.7) 2.0-7.5
Lymphocytes 0.9 x 10 9 /L (0.7 -1.3) 1.5-4.0
Platel ets 183 x 10 9 /L (147 -223) 150-400
PTT 34.0 s (29.7 -36.1) 28-40
INR 1.0 (1.0 -1.1) 0.8-1.2
LDHAdmission
Median1 396 U/L (219-629)No. abnormal2 86/99 (87%)
During Hospitalization3
Median 630 U/L (363-1156)No. abnormal2 115/123 (94%)
Notes: 1For all laboratory values the median and the 25th and 75th
percentiles are presented.2Abnormal values are those > 190 U/L.3These values reflect the most abnormal values during hospitalization.
Creatine KinaseAdmission
Median 157 U/L (70-310)No. abnormal1 43/109 (39%)
During HospitalizationMedian 370 U/L (208-959)No. abnormal1 64/118 (54%)
Note: 1Abnormal values are those >240 for males and > 150 for females.
3638
4042
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Maximum Daily Temperature
Day of Hospitalization
Max
imum
Tem
pera
ture
(C)
144 144 142 138 133 119 100 78 63 55 47 41 34 26 23 16 10 7 4 3 3N=
Treatment
Treatment Proportion Cumulative % Cumulative %Receiving Started by Day 1 Started by Day 2
Ribavirin 126 (88%) 76% 91%
Steroids 58 (40%) 31% 40%
Antibiotics 137 (95%) 79% 94%
Ribavirin Therapy
Route of administrationIV 85 (67.5%)PO 4 (32.%)Both 37 (2.4%)
Median duration of treatment 6 (5-7) days
Outcomes1
Deaths 8/144 (6%)
Alive 136/144 (94%)
Discharged 103/144 (72%)
Still hospitalized 33/144 (23%)– 8 patients (6%) still ventilated
Note: 1Outcomes as of April 17 2003.
OutcomesOf the 8 deaths:
6/8 had diabetes (75%)
• One of the patients without diabetes had cancer• One patient had no medical co-morbidity other
than being a former smoker
(omitting dead)
Days from Hospital Admission
Prop
ortio
n St
ill in
Hos
pita
l
0 5 10 15 20 25 30
0.0
0.2
0.4
0.6
0.8
1.0
Time to Death
Days from Hospital Admission
Prop
ortio
n Al
ive
0 10 20 30
0.0
0.2
0.4
0.6
0.8
1.0
Time from Admission to Death
Days from Hospital Admission
Prop
ortio
n Al
ive
0 10 20 30
0.0
0.2
0.4
0.6
0.8
1.0
Age<60; n=11460+; n=30
Predictors of Poor Outcome
Poor outcome defined as: death, ventilation, or ICU admission
Incidence of poor outcome 30/144 (21%)
Univariate AnalysisVariable RR 95% CI P value1
Age 60 or greater 1.9 1.3-2.7 <0.001Ribavirin used 1.9 0.45-8.0 0.363Diabetes 5.4 2.5-11.5 <0.001Any co-morbidity2 4.4 2.1-8.9 <0.001
Note: 1P value calculated using Cox proportional hazards model.2Any co-morbidity includes diabetes, COPD, cancer, and
cardiac disease.
Multiple Regression Analysis• a priori hypothesis of age and co-morbidities being associated
with poor outcome
Variable RR 95%CI P value1
Diabetes 3.1 1.4-7.2 0.01Other co-morbidity2 2.5 1.1-5.8 0.03Age 60 or greater 1.4 0.95-2.1 0.09
Note: 1P value calculated using Cox proportional hazards model.2Other co-morbidites include COPD, cancer, and cardiac disease.
Time from Admission to Poor Outcome
Days from Hospital Admission
Prop
ortio
n w
ithou
t Poo
r Out
com
e
0 5 10 15 20 25 30
0.0
0.2
0.4
0.6
0.8
1.0
Age<6060+
Time from Admission to Poor Outcome
Days from Hospital Admission
Prop
ortio
n w
ithou
t Poo
r Out
com
e
0 5 10 15 20 25 30
0.0
0.2
0.4
0.6
0.8
1.0
TreatmentRibavirin-; n=18Ribavirin+; n=126
Time from Admission to Poor Outcome
Days from Hospital Admission
Prop
ortio
n w
ithou
t Poo
r Out
com
e
0 5 10 15 20 25 30
0.0
0.2
0.4
0.6
0.8
1.0
No comorbid illness; n=115
Other+/Diabetes-; n=13
Other-/Diabetes+; n=8
Other+/Diabetes+; n=8
Conclusions1. The majority of cases were acquired in hospital
(healthcare workers, patients and visitors) and most of those occurred in one hospital before intensive respiratory precautions were instituted for both patients and their contacts.
2. Fever is very close to the first symptom in almost everyone.
3. Rhinorrhea is not a common presenting symptom of SARS.
Conclusions4. Many patients were evaluated and sent home prior
to admission to hospital (perhaps because the signs and symptoms are so non-specific).
5. The most useful feature on physical exam is elevated temperature.
6. The current WHO, CDC, and Health Canada definitions of suspect SARS exclude 11% of patients who have fever, contact and pulmonary infiltrates with NO respiratory symptoms.
7. 25% of patients have a normal CXR on admission.
Conclusions8.The hallmark laboratory findings are
lymphopenia and elevated LDH.
9.Many patients also demonstrate low calcium, phosphate, magnesium, and potassium levels and elevated CK on admission to hospital.
10.The pre-existing electrolyte abnormalities tend to get worse in hospital.? 2° to Ribavirin and other therapies?
Conclusions11. Ribavirin is associated with many side effects,
especially hemolysis and transaminitis.
12. Diabetes and other co-morbidities are independently associated with poor outcome.
13. Based on short-term outcome data (30 days), the vast majority (94%) of people survive SARS.
Clinical progression and viral load in a community outbreak
of coronavirus-associated SARS pneumonia: a prospective study
(Peiris et al. Lancet, 2003:361)
Methods
• Between March 24 and 28, 2003 75 patients admitted from Amoy Gardens
• Followed prospectively• All patients treated with ribavirin for 14
days and prednisolone for 13 days
Results
• All but one patient became afebrile within 48 hours, but fever recurred in 64 (85%) of patients by 8-9 days
Infection control for SARS
How is SARS spread?• MOST OFTEN spread by contact and or droplet
– That is, touching a patient or their secretions directly (and then touching your face), or having droplets from their breathing, speaking, coughing etc. land on your hands or face
• Other possible routes– Airborne (breathing same air without N95 mask)– Contact with contaminated environment– Re-aerosolization of droplets (eg. When mask
removed, or with toilet flushing or bed sheets shaken out)
How can we prevent transmission? I
• Ensure that all patients who might have SARS are rapidly identified and managed in precautions
• Minimize the opportunities for exposure of staff/other patients to SARS patients
• Minimize the number of droplets the patient produces (eg. minimize coughing, vomiting)
How can we prevent transmission? II
• Control air flow and air exchanges • Use N95 masks to protect against possibility of
airborne spread • Use barriers to prevent direct contact and droplet
contact• Handle patient area (eg. Linens) and remove
barriers so as to prevent re-aerosolization• Repeated, thorough cleaning of the environment
Identification/management of patients
• Fever surveillance in patients– All patients with fever assessed for SARS risk,
maintained in SARS precautions
• Fever/symptom surveillance in staff– Occupational health assessment of staff with
fever, myalgias, new cough
Managing Known SARS patientsRoom Placement/Entry
• Airborne isolation rooms or SARS unit (negative pressure, at least 6 air exchanges per hour)
• Only essential staff enter room/unit• Minimize time in room • Minimize time within six feet of patient
– HCW position to avoid droplets in front of patient’s face• Minimize amount of direct contact with patient• Do not go into patient’s bathroom unless
essential for patient care
Managing Known SARS PatientsReducing Droplets
• Medical management to reduce cough• Medical management to reduce nausea and
prevent vomiting• No nebulizer treatments• Supply oxygen dry; by nasal prongs if
possible• Patient to wear surgical mask at all times
when HCW are in the room• Handle bed linens to avoid creating aerosols
Managing Known SARS PatientsProtective Barriers - 1
• N95 mask • Face shield (fluid shield mask worn
upside down)• Cap/Hair cover• Gown• Double Glove
Managing Known SARS PatientsProtective Barriers - 2
• N95 mask– Ensure fits on face– Comfortable enough so that does not need
adjustment while garbed• Ensure overlap between gloves and gown cuff• Double glove
– Wear first pair for direct contact with patient, then remove
– If top pair of gloves contaminated (eg cleaning vomit), remove and replace
Managing Known SARS PatientsProtective Barriers - 3
• Protect face– Consciously keep hands away from
face/head/neck while in room– Ensure hair is tied or clipped back so that
hands do not move to adjust• Do not check pager, or answer phone
while in room
Managing Known SARS PatientsRemoving Barriers - 4
• At door to room, remove gloves, then gown• Disinfect hands with alcohol handwash in the room• Leave the room• Disinfect hands• Remove hair cover• Hold the mask/face shield by the edge of the face shield
and lift it up over your head• Remove N95 mask, by holding at the bottom and lifting it
up over your head• Disinfect hands• Put on a clean N95 mask, then a clean gown
High risk activities
• Intubation• Noninvasive positive pressure ventilation• Manual bagging• Nebulized medication administration• Use of Venturi mask• Tracheal and oropharyngeal suction• Nasopharyngeal aspiration / throat swab• Percussion chest physiotherapy
High risk activities (cont’d)• Manual bagging
– Avoid where possible; minimize time• Tracheal and oropharyngeal suction
– Always used closed suction• Nasopharyngeal aspiration / throat swab
– Use nasal, not NP swab– Perform swab with mask over mouth, and
tissues at hand for the patient
Intubation for SARS patients
• Elective intubation preferred• Negative pressure, well ventilated room• Minimize number of people in room• Most experienced staff members only• Protective gear, as usual, with addition of PAPR • Avoid manual bagging• Perform procedure that is safe for patient, while
minimize cough and other droplet producing effects/procedures
Protective Barriers: N95 masks, face shields, gown and gloves
Removing Barriers
At door to room, remove gloves, then gown
Removing Barriers
Disinfect hands with alcohol handwash in the room
Removing Barriers
Leave the room
Removing Barriers
Disinfect hands
Removing Barriers
Hold the face shield by the edge of the face shield and lift it up over your head
Removing Barriers
Remove N95 mask, by holding at the bottom and lifting it up over your head
Removing Barriers
Remove hair cover
Removing Barriers
Disinfect hands
Protective Barriers
Put on a clean N95 mask, a clean gown, and hair cover
Heightened Awareness
Toronto Area Probable and Suspect cases by source of infectionMay 5, 2003
0
2
4
6
8
10
12
23-F
eb-0
325
-Feb
-03
27-F
eb-0
301
-Mar
-03
03-M
ar-0
305
-Mar
-03
07-M
ar-0
309
-Mar
-03
11-M
ar-0
313
-Mar
-03
15-M
ar-0
317
-Mar
-03
19-M
ar-0
321
-Mar
-03
23-M
ar-0
325
-Mar
-03
27-M
ar-0
329
-Mar
-03
31-M
ar-0
302
-Apr
-03
04-A
pr-0
306
-Apr
-03
08-A
pr-0
310
-Apr
-03
12-A
pr-0
314
-Apr
-03
16-A
pr-0
318
-Apr
-03
20-A
pr-0
322
-Apr
-03
24-A
pr-0
326
-Apr
-03
28-A
pr-0
330
-Apr
-03
02-M
ay-0
304
-May
-03
Date of onset of first symptoms
Num
ber o
f cas
es (P
& S
)TravelNon health careHealth care settings