Person-to-Person Enteric Disease Outbreak
Surveillance, 2009-2010
Mary Wikswo, MPH
Epidemiologist
7th Annual Meeting for OutbreakNet
September 21, 2011
National Center for Immunization & Respiratory Diseases
Division of Viral Diseases
The National Outbreak Reporting System (NORS)
Result of 2006 CSTE resolution
Launched in February 2009
Web-based platform
Adapted from eFORS
Includes all 50 states, Washington DC, and 8 US territories
Supports reporting of
•
•
•
•
•
•
All waterborne disease outbreaks
Enteric foodborne disease outbreaks
Enteric person-to-person transmitted disease outbreaks
Enteric animal contact-associated disease outbreaks
Enteric environmental exposure-associated outbreaks
Other enteric outbreaks of unknown mode of transmission
First national system for reporting person-to-person
(P2P) acute gastroenteritis (AGE) outbreaks
Analyzing NORS-P2P Data
Inclusion criteria:
First illness of outbreak occurred in 2009-2010
Primary mode of transmission was person-to-person
NORS report marked as “finalized”
Exclusion criteria:
Total number of primary cases not entered
Total number of primary and secondary cases was less than 2
Etiology was non-enteric pathogen (e.g. measles, scabies,
Hepatitis A)
All data current as of July 28th, 2011
Uptake of NORS-P2P Reporting
2183 reports from 42 reporting sites
Reports from 41 US states and Washington, D.C.
985 reports in 2009 and 1198 in 2010
5/42 reporting sites did not enter any 2009 reports
Earliest first ill date of P2P outbreaks reported in NORS by site
No data
Jan-Jun 2009
DC
Jul-Dec 2009
Jan-Jun 2010
Jul-Dec 2010
P2P Outbreaks by State
Median of 7 reports annually per site (range 0-151)
Median of 5 average annual reports per million
population1 (range 0.03-38)
Average annual number of NORS-P2P reports per million population1 by site,
2009-2010
No data
<0.462
0.46-4.77
DC
4.78-11.18
>11.18
1Based on
US Census estimated population, 2009
quartiles
2Categories based on
P2P Outbreak Etiologies
36% of reports have no known or suspected etiology
Less than half of outbreaks have a confirmed* etiology
Norovirus most common etiology
Confirmed and suspected
outbreak etiologies (N=2183)
Confirmed* outbreak etiologies
(N=992)
5%
9%
56%
Norovirus
36%
Shigella
Other/multiple
86%
Unknown
4%
4%
*≥2 lab-confirmed cases
Other/Multiple Etiologies
Confirmed and Suspected
Confirmed1
Salmonella2
14
153
E. coli
13
13
rotavirus
10
8
Giardia lamblia
6
5
Cryptosporidium4
4
4
Clostridium difficile
4
3
sapovirus
2
2
Campylobacter jejuni
1
1
Cyclospora cayetanensis
1
1
norovirus and Clostridium5
5
3
norovirus and Bacillus (unspecified)
1
1
norovirus and rotavirus
1
1
Salmonella enterica and E. coli3
1
0
norovirus and human metapneumovirus
1
0
norovirus, rotavirus, and C. difficile
1
1
Etiology
1
≥2 lab-confirmed specimens
and one unspecified species
3 Includes one outbreak of confirmed S. enterica with suspected E. coli
2 Includes S. enterica
4
Includes C. parvum, C. hominis, and one unspecified species
C. perfringens
5 Includes C. difficile and
Seasonality of P2P Outbreaks by Etiology
300
Other/multiple
250
Number of outbreaks
Shigella
Norovirus
200
Unknown
150
100
50
0
Month of first illness
Ages of Primary Cases in P2P Outbreaks
57% of cases in norovirus outbreaks >49 years old
77% of cases in Shigella outbreaks <10 years old
100%
80%
60%
Unknown age
>49 years
10-49 years
<10 years
40%
20%
0%
Norovirus
Shigella
Other/multiple
No etiology given
Confirmed/suspected outbreak etiology
Settings of P2P Outbreaks
Most norovirus and unknown etiology outbreaks occur
in nursing homes
Almost all Shigella outbreaks occur in child daycares
Etiology
(confirmed or
suspected)
Nursing
home
(%)
Daycare
(%)
Hospital
(%)
School
(%)
Other
(%)
Total
(%)
Norovirus
565 (83)
13 (2)
27 (4)
19 (3)
55 (8)
679 (100)
0 (0)
29 (97)
0 (0)
0 (0)
1 (3)
30 (100)
Other/multiple
11 (38)
9 (31)
0 (0)
2 (7)
7 (24)
29 (100)
No etiology given
304 (78)
15 (4)
21 (5)
24 (6)
26 (7)
390 (100)
Any etiology
880 (78)
66 (6)
48 (4)
45 (4)
89 (8)
1128
Shigella
Settings of P2P Outbreaks
Most norovirus and unknown etiology outbreaks occur
in nursing homes
Almost all Shigella outbreaks occur in child daycares
Etiology
(confirmed or
suspected)
Nursing
home
(%)
Daycare
(%)
Hospital
(%)
School
(%)
Other
(%)
Total
(%)
Norovirus
565 (83)
13 (2)
27 (4)
19 (3)
55 (8)
679 (100)
0 (0)
29 (97)
0 (0)
0 (0)
1 (3)
30 (100)
Other/multiple
11 (38)
9 (31)
0 (0)
2 (7)
7 (24)
29 (100)
No etiology given
304 (78)
15 (4)
21 (5)
24 (6)
26 (7)
390 (100)
Any etiology
880 (78)
66 (6)
48 (4)
45 (4)
89 (8)
1128
Shigella
Estimated1 Case Outcomes in P2P Outbreaks
Norovirus causes most deaths and hospitalizations
Shigella outbreak cases most likely to seek health care
Etiology
Norovirus
Hospitalized
Deaths (%)
cases
(%)
Cases visiting
the ED
(%)
Cases seeking
health care2
(%)
Total
primary ill
141 (0.3)
1242 (2)
1120 (2)
5359 (10)
53914
Shigella
0 (0)
69 (5)
166 (13)
898 (70)
1276
Other/
multiple
6 (0.4)
70 (5)
72 (5)
333 (23)
1422
No etiology
given
24 (0.1)
473 (2)
384 (2)
1394 (7)
21217
Any etiology
172 (0.2)
1867 (2)
1807 (2)
8949 (11)
77829
1Estimated by
2
applying proportion of known case outcomes to total illnesses
Excluding hospitalizations and ED visits
Attack Rates in P2P Outbreaks
Attack rates highest in norovirus outbreaks and lowest
in Shigella outbreaks
Attack rates higher among guests/residents compared
with staff/crew
Etiology
Median
guest/resident
attack rate
(%)
Range
(%)
Median
staff/crew
attack rate
(%)
Range
(%)
Norovirus
35
0.1-100
19
0-100
Shigella
12
3-51
8
0-38
Other/multiple
32
0-78
13
0-75
No etiology given
22
1-100
8
0-100
Any etiology
30
0-100
13
0-100
Total # of outbreaks
918
714
Conclusions
NORS provides first national P2P outbreak data
P2P outbreaks are a significant cause of AGE
Mean of 1092 outbreaks and 38,915 illnesses per year
Compare to 685 foodborne disease outbreaks and 13,952 illnesses
in 2009 reported via NORS1
Norovirus is leading cause of P2P outbreaks
Mean of 26,957 illnesses and 613 outbreaks per year
Estimated 71 outbreak-associated deaths reported per year
Shigella also common cause of P2P outbreaks
Mean of 46 outbreaks and 638 illnesses per year
Compare to 3 foodborne outbreaks and 39 illnesses in 20092
1Unpublished data
2Foodborne
Outbreak Online Database (FOOD), http://wwwn.cdc.gov/foodborneoutbreaks
Limitations
State and local health departments vary in capacity
Resource limitations
Competing responsibilities
Many reports missing etiology and/or setting data
Varying definitions and capacities for lab confirmation
Limited laboratory resources
CDC definition is ≥2 lab-confirmed cases
NORS is dynamic
Reporting sites may edit, add, or delete reports at any time
New system with variable uptake and utilization
Data may become more consistent and reliable over time
A Look Ahead
NORS breakout session in International I/II/III (front)
Posters #1-3 in Catalina at 5:00pm
Surveillance summary of 2009-2010 NORS-P2P data
New NORS version later this year
Updated Full Download
PDF download
New feature - NORSDirect
Allow states to directly upload outbreak data from existing
databases
Initial piloting of this feature planned for October 2011
New NORS website
Integration with CaliciNet
Acknowledgements
CDC Division of Foodborne, Waterborne, and Environmental Diseases
Virginia Roberts
Rickey Zachary
Jonathan Yoder
Franky Maslim
Karunya Manikonda
Darlene Arnold
Karen Herman
Jason Price
Dana Cole
Kelly Walsh
Amy Nisler
Shacara Johnson
Elisabeth Honorat
Antonio Vieira
Weidong Gu
LaTonia Richardson
Hannah Gould
CDC Division of Viral Diseases
Aron Hall
State and Local Public Health Agencies
Thank you!
For additional questions/comments, please contact us at
NORSAdmin@cdc.gov
For more information please contact Centers for Disease Control and Prevention
1600 Clifton Road NE, Atlanta, GA 30333
Telephone: 1-800-CDC-INFO (232-4636)/TTY: 1-888-232-6348
E-mail: cdcinfo@cdc.gov Web: http://www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the
Centers for Disease Control and Prevention.
National Center for Immunization & Respiratory Diseases
Division of Viral Diseases