Surveillance
Dona Schneider, PhD, MPH
 Surveillance is the ongoing,
systematic collection, analysis, and
interpretation of health data
essential to the planning,
implementation, and evaluation of
public health practice, closely
integrated with the timely feedback
of these data to those who need to
know.
Centers for Disease Control
Surveillance can…
Estimate the magnitude of a problem
Determine geographic distribution of illness
Detect epidemics/outbreaks
Generate hypotheses, stimulate research
Evaluate whether control measures work
Monitor changes in infectious agents
Detect changes in health practices
30
25
CASES







20
15
10
5
0
TIME
Examples:
Morbidity and Mortality Weekly Report
http://www.cdc.gov/mmwr/
SEER Cancer Registry
http://seer.cancer.gov/
US Vital Statistics
http://wonder.cdc.gov/welcome.html
National Notifiable Diseases Surveillance
System (NNDSS) – produces the data in the
MMWR
 The reportable diseases list is revised periodically
by the Council of State and Territorial
Epidemiologists (CSTE) and the Centers for
Disease control (CDC)
 States report their cases to the CDC
 Internationally quarantinable diseases (i.e.,
cholera, plague and yellow fever) must be
reported to the World Health Organization (WHO)
The Epidemic and Pandemic Alert and
Response (EPR) Program at the WHO
Monitors…
 Anthrax
 Avian influenza
 Crimean-Congo
haemorrhagic fever (CCHF)
 Dengue/dengue
haemorrhagic fever
 Ebola haemorrhagic fever
 Hepatitis
 Influenza
 Lassa fever





Marburg haemorrhagic fever
Meningococcal disease
Plague
Rift Valley fever
Severe Acute Respiratory
Syndrome (SARS)
 Smallpox
 Tularaemia
 Yellow fever
Surveillance for communicable
diseases is important…
 The world population is
highly mobile
 International travel and
troop movements increase
the risk of communicable
disease transmission
 Forced migration for war
and famine, and voluntary
immigration increase
communicable disease risk
Types of Surveillance
 Passive
 Inexpensive, provider-initiated
 Good for monitoring large numbers of typical health events
 Under-reporting is a problem
 Active
 More expensive, Health Department-initiated
 Good for detecting small numbers of unusual health events
 Enhanced
 Rapid reporting and communication between surveillance
agencies and stakeholders
 Best for detecting outbreaks and potentially severe public
health problems
Syndromic surveillance
 Allows us to identify groups of
signs and symptoms that precede
diagnosis and signal a sufficient
probability of a case or an outbreak
that warrants a further public
health response
 Example: EBOLA VIRUS
Sentinel Surveillance
 Monitors
 Sites – volcanos
 Events – 9/11
 Providers – ERs
 Vectors/animals
• Rabies
• West Nile
SENTINEL EVENT
Nov 12, 2001 - 9:17 am
Flight AA 587 Crashes in Rockaways
7-Zip Surveillance showed:
27 Obs / 10 Exp Resp Emergencies
p<0.001
31 Obs / 16 Exp Hospital Events
p<0.05
10
/2
5
10 /20
/2 01
7
10 /20
/2 01
9
10 /20
/3 01
1/
2
11 00
/2 1
/2
11 00
/4 1
/2
11 00
/6 1
/2
11 00
/8 1
11 /20
/1 01
0
11 /20
/1 01
2
11 /20
/1 01
4
11 /20
/1 01
6
11 /20
/1 01
8
11 /20
/2 01
0
11 /20
/2 01
2
11 /20
/2 01
4
11 /20
/2 01
6
11 /20
/2 01
8
11 /20
/3 01
0/
2
12 00
/2 1
/2
12 00
/4 1
/2
12 00
/6 1
/2
12 00
/8 1
12 /20
/1 01
0
12 /20
/1 01
2
12 /20
/1 01
4
12 /20
/1 01
6
12 /20
/1 01
8/
20
01
Resp/None Syndromes
40
35
Rockaways
30
Rest of City
25
20
15
10
5
0
Date
Investigation
 Chart review in one hospital (9 cases)





Smoke Inhalation (1 case)
Atypical Chest Pain / Anxious (2 cases)
Shortness of Breath - Psychiatric (1 case)
Asthma Exacerbation (3 cases)
URI/LRI (2 cases)
 Checked same-day logs at 2 hospitals
Increase not sustained
Cipro and Doxycycline
Prescriptions
250000
40000
Cipro
Doxycycline
35000
200000
30000
25000
First anthrax case
reported, 10/4/01.
150000
20000
100000
15000
CDC recommends
doxycyline 10/28/01.
9/11
10000
50000
5000
0
7/1/2001
0
7/29/2001
8/26/2001
9/23/2001
10/21/2001
11/18/2001
12/16/2001
1/13/2002
Blood Lead Measurements 1975-1981
110
18
Predicted blood lead
100
Lead used
in
90
gasoline
(thousands
of tons) 80
16
Mean
blood
lead
14 levels
 g/dl
Gasoline lead
70
Observed blood lead
12
60
50
10
40
30
1975
1976
1977
1978
1979
1980
1981
8
Year
Source: Pirkle et al JAMA 272:284-91, 1994
Reported Salmonella Isolates,*
United States, 1976-2001
*Data from Public Health Laboratory Information System (PHLIS).
Source: CDC. Summary of notifiable diseases. 2001.
8/
12
/
9/ 20 0
9
10 /20 0
/7 0
11 /20 0
/4 0
12 /20 0
12 /2/2 00
/3 0 0
0
1/ /2 0 0
27 0
2/ /20 0
24 0
3/ /20 1
24 0
4/ /20 1
21 0
5/ /20 1
19 0
6/ /20 1
16 0
1
7/ /20
14 01
8/ /20
11 0
/ 1
9/ 20 0
8
10 /20 1
/6 0
11 /20 1
/3 0
12 /20 1
12 /1/2 01
/2 0 0
9
1/ /2 0 1
26 0
2/ /20 1
23 0
3/ /20 2
23 0
4/ /20 2
20 0
5/ /20 2
18 0
6/ /20 2
15 0
2
7/ /20
13 02
/2
00
2
Units per 100,000 prescriptions
Tobacco Cessation Aids Sold at a Large
Pharmacy Chain
$0.39
400
$1.42
increase
in City
increase in
tax
State tax
350
300
250
200
150
100
50
0
Week Ending
Recent Occupational Monitoring
Efforts for Sentinel Events Include…
 Biodetection Systems (BDS) in NJ post
offices to detect anthrax and soon, ricin
 Biowatch, an air monitoring system in New
York City and 30 other cities
Free Resources
World Health Organization
DISMOD Software
http://www.who.int/healthinfo/boddismod/en/
Centers for Disease Control
Epi Info and Epi Map
http://www.cdc.gov/epiinfo/
Good surveillance does not
necessarily ensure the making of
right decisions, but it reduces the
chances of wrong ones.
Alexander D. Langmuir
NEJM 1963;268:182-191