Dr.Somsak Wattanasri, M.D.Board of Pediatrics, FETPdoes@health.moph.go.th

Bureau of EpidemiologyDepartment of Disease Control

Ministry of Public Health

COMMUNICABLE DISEASE SURVEILLANCE

EpidemiologyEpidemiology andand Public HealthPublic Health

“Laws of nature mattered for healthone could not understand the public rate of disease simply by studying individuals. .... “

Dr. Somsak Wattanasri

DefinitionDefinition ofofepidemiologyepidemiology

TheThe studystudy ofof thethe distributiondistribution andanddeterminantsdeterminants ofof thethe healthhealth statusstatus or or eventseventsin in thethe populationpopulation andand itsits applicationapplication to to control public control public healthhealth problemsproblems

Source: Source: LastLast 2001. A Dictionary of Epidemiology: 42001. A Dictionary of Epidemiology: 4thth Edition. Oxford University Press: New Edition. Oxford University Press: New York.York.

Basic Epidemiological ConceptBasic Epidemiological Concept

Community Health ProblemCommunity Health Problem

FactsFacts

-- WHATWHAT-- WHOWHO-- WHEREWHERE--WHENWHEN--HOW MUCHHOW MUCH-- WHYWHY-- HOWHOW

ToolsTools–– Descriptive Epidemiology (generate hypotheses)Descriptive Epidemiology (generate hypotheses)

PersonPerson–– Age, sex, occupationAge, sex, occupation

PlacePlace–– Spot mapSpot map

TimeTime–– Epidemic curveEpidemic curve

Interview cases Interview cases -- hypothesis generationhypothesis generation

–– Analytic Epidemiology (test hypotheses)Analytic Epidemiology (test hypotheses)22--xx--2 Tables2 Tables

–– Associations between outcome (e.g., illness) and exposure (e.g.,Associations between outcome (e.g., illness) and exposure (e.g.,food eaten)food eaten)

More sophisticated analysesMore sophisticated analyses

surveillancesurveillance

An ongoing systematic observation of An ongoing systematic observation of the incidence of CD, NCD, Injury or the incidence of CD, NCD, Injury or any health problems to gain specific any health problems to gain specific data , information for further action to data , information for further action to control and prevent public health control and prevent public health problemproblem

EPIDEMIOLOGICAL SURVEILLANCEEPIDEMIOLOGICAL SURVEILLANCE

DATADATA INFORMATIONINFORMATION

ACTIONACTION

CASE DEFINITIONCASE DEFINITION

standardizestandardize

uniformly applieduniformly applied

Why disease surveillance?

It uses a data model, standardizes, fair. It emphasizes quality in data and work.It links analysis, prevention, and control.It’s been tested. It works.Its benefit to costs is large and undeniableIt is additive: recommends, teaches, and builds to a logical experiment andbelievable results.

III. Source of information

1. Morbidity2. Mortality3. Laboratory4. Vaccines and drug5. Outbreak news/ rumor6. Vector7. Behavior8. Environmental8. Demographic

Important CD Diseases

Notification within 24 hours1 SARS and Avian Flu 2.Cholera 3. Acute severely ill or death of unknown etiology 4. Cluster of diseases with unknown etiology 5. Anthrax 6. Meningococcal meningitis 7. Food poisoning outbreak 8. Encephalitis 9. Acute flaccid paralysis (AFP) 10. Severe Adverse Events Following Immunization

๑๑ Diptheria ๑๒ Rabies

Important CD Diseases

1 Measles 2. Pertussis3. Hand Foot and Mouth Diseases 4. Influenza 5. Leptospirosis6. Dysentery 7. Severe pneumonia of unknown etiology 8. Cluster of infectious cases9. Dengue/DHF

Organization of Surveillance SystemOrganization of Surveillance System

Ministry of Public Health

Dep of Disease ControlInternational Organization

Bureau of Epidemiology

Provincial Epidemiological Unit

Private hospitals and clinicsHospitals and clinic under

universal coverage scheme

District Surveillance

information center

Hospitals

Under MOH

And universal coverage schemes

ขอมูลรายงานโรค

ขาวสาร/ขาวกรอง

Regional Disease

Control Center

TThehe epidemiologicalepidemiological ppracticesractices

506/507

Report

E.1

E.0

D.R.

E.2

E.3

E.4

TIME

PERSON

PLACE

TABLE

CHART

GRAPHANALYSIS &

INTERPRETATION

NORMAL

KNOWLEDGE

ABNORMAL

RECOMMENDATION RECOMMENDATION && ACTIONACTION

INVESTIGATIONReview other outbreaks

and other source of

information EPIDEMIOLOGICAL STUDY

Acute Viral Hepatitis, Acute Viral Hepatitis, Thailand 2005 Thailand 2005

Thailand have surveillance of acute viral Thailand have surveillance of acute viral hepatitis for 5 extinct viruses : hepatitis for 5 extinct viruses :

1971 began with Total Acute Hepatitis ( 1971 began with Total Acute Hepatitis ( infectious, serum) infectious, serum)

1980 established Hepatitis A, Hepatitis B 1980 established Hepatitis A, Hepatitis B and Non A , Non B and Non A , Non B

1997 fully divided into 5 extinct viral 1997 fully divided into 5 extinct viral hepatitis, A , B, C, D and Ehepatitis, A , B, C, D and EHepatitis B vaccine was routinely introduced Hepatitis B vaccine was routinely introduced nationwide in 1992nationwide in 1992

Case Definition for Case Definition for SurveillanceSurveillanceClinical CriteriaClinical Criteria

Have jaundice without receiving Have jaundice without receiving hepatotoxichepatotoxicagents and at least one of the following agents and at least one of the following -- Dark urineDark urine-- FeverFever-- Abdominal discomfortAbdominal discomfort-- Right upper quadrant painRight upper quadrant pain-- AnorexiaAnorexia-- Fatigue/WeaknessFatigue/Weakness

Case Definition for SurveillanceCase Definition for SurveillanceLaboratory CriteriaLaboratory Criteria

General LabGeneral Lab--SGPT (ALT) > 100 U/L in all age groupSGPT (ALT) > 100 U/L in all age groupSpecific LabSpecific Lab1. Hepatitis A:1. Hepatitis A: Positive anti HAV Positive anti HAV IgMIgM2. 2. Hepatitis B:Hepatitis B: Positive anti Positive anti HBcHBc IgMIgM and/or and/or

positivepositive anti anti HBsHBs IgMIgM and/or positive and/or positive HBsHBs AgAg3. 3. Hepatitis C:Hepatitis C: Positive anti HCV (total Positive anti HCV (total antibody) antibody)

and/or detectand/or detect HCV RNA HCV RNA 4. 4. Hepatitis D:Hepatitis D: PositivePositive HBsHBs agag withwith anti HDV anti HDV

IgGIgG5. 5. Hepatitis E:Hepatitis E: Positive anti HEV Positive anti HEV IgMIgM

Case ClassificationCase Classification

Suspected case Suspected case

Refer to patient who met clinical Refer to patient who met clinical criteriacriteria

Probable caseProbable case

Refer to patient who met clinical Refer to patient who met clinical criteria and criteria and SGPT (ALT) >100 U/LSGPT (ALT) >100 U/L

Confirmed caseConfirmed case

Refer toRefer to patient who met clinical patient who met clinical criteria and has confirmed specific criteria and has confirmed specific laboratory testinglaboratory testing

Number of Hepatitis A Cases by Number of Hepatitis A Cases by week of onset, Thailand, 2003week of onset, Thailand, 2003--20072007

Number of Hepatitis B Cases by Number of Hepatitis B Cases by week of onset, Thailand, 2003week of onset, Thailand, 2003--20072007

Number of Hepatitis C Cases by Number of Hepatitis C Cases by week of onset, Thailand, 2003week of onset, Thailand, 2003--20072007

Number of Hepatitis D Cases by Number of Hepatitis D Cases by week of onset, Thailand, 2003week of onset, Thailand, 2003--20072007

Number of Hepatitis E Cases by Number of Hepatitis E Cases by week of onset, Thailand, 2003week of onset, Thailand, 2003--20072007

Summarized of Acute Viral Hepatitis Summarized of Acute Viral Hepatitis A,B and C, Thailand 2005A,B and C, Thailand 2005

VirusVirus No of No of CaseCase

Median Median ageage SexSex HospitalizeHospitalize

dd

Hepatitis AHepatitis A 2,4212,421

2,7422,742

407407

22 years22 years(14,33)(14,33)

M:FM:F1.5:11.5:1

10.6%10.6%

Hepatitis BHepatitis B33 years33 years(22,44)(22,44)

M:FM:F1.5:11.5:1

12.3%12.3%

Hepatitis CHepatitis C42 years42 years(30,53)(30,53)

M:FM:F1.5:11.5:1

12.0% 12.0%

Hepatitis A Cases by Age, Hepatitis A Cases by Age, Thailand 2005Thailand 2005

Hepatitis B Cases by Age, Hepatitis B Cases by Age, Thailand 2005Thailand 2005

Hepatitis C Cases by Age, Hepatitis C Cases by Age, Thailand 2005Thailand 2005

Rate of Hepatitis B Rate of Hepatitis B Infection, Infection, 19801980--2005 , Thailand2005 , Thailand

0

1

2

3

4

5

6

7

80 82 84 86 88 90 92 94 96 98

2000

2002

2004

Rate/100,000

Year

HB Vaccine, 1992

Source: Report 506, BoE

PersonPlace

Time

Cases

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10

0200400600800

10001200

0-4 '5-14 '15-44

'45-64

'64+

Age Group

Evaluate information

Pathogen? Source? Transmission?32

Key Principles of Epidemiology Key Principles of Epidemiology ((RERFARERFA))

Compare Compare RRatesates

Know the Know the EExpectedxpected

Use Use RRandom Controls andom Controls

Provide Provide FFeedbackeedback

Take Take AActionction

Compare Compare RRates (not cases)ates (not cases)Count cases, of course, but compare Count cases, of course, but compare ratesrates–– Rate requires numerator and denominatorRate requires numerator and denominator

Numerator: casesNumerator: cases

Denominator: Population or persons Denominator: Population or persons at riskat riskof being in the numeratorof being in the numeratorOne case may or may not be significantOne case may or may not be significant

NumeratorNumerator Number of casesNumber of casesRATE =RATE = ------------------------------------

==----------------------------------------------

DenominatorDenominator Number at riskNumber at risk

When you have a rate, it must be When you have a rate, it must be compared to the rate you expectcompared to the rate you expectThis is why we do routine surveillanceThis is why we do routine surveillance–– To know what is the expectedTo know what is the expected

Definition of an epidemic:Definition of an epidemic:–– More than the expected, more than usualMore than the expected, more than usual

To what can you compare when no To what can you compare when no surveillance has been done?surveillance has been done?–– Create comparison groups of Create comparison groups of controlscontrols

Know the Know the EExpected (by xpected (by surveillance)surveillance)

Using the best data and evidence, Using the best data and evidence, have the courage to take actionhave the courage to take action–– John Snow exampleJohn Snow example–– AIDS in AmericaAIDS in America

Blood banking industry (Red Cross, AABB) Blood banking industry (Red Cross, AABB) refused to acknowledge transfusion riskrefused to acknowledge transfusion risk

–– Don Francis and Jim Curran of CDC forced the Don Francis and Jim Curran of CDC forced the issue in public meetingsissue in public meetings

–– SARS in AsiaSARS in AsiaUnprecedented WHO criticism of a member Unprecedented WHO criticism of a member state for suppressing SARS casesstate for suppressing SARS cases

Take Take AAction (ction (““pp valuevalue”” not not enough)enough)

Use Use RRandom controls (avoid bias)andom controls (avoid bias)

When lacking surveillance, proper controls When lacking surveillance, proper controls create onecreate one’’s comparison groups comparison group–– Similar to cases except without the outcome Similar to cases except without the outcome

(disease)(disease)Retrospective studies (case control)Retrospective studies (case control)Prospective studies (cohort, intervention trial)Prospective studies (cohort, intervention trial)

Random selection: every member of target Random selection: every member of target group has equal chance of selectiongroup has equal chance of selection–– Avoid conscious or subconscious biasAvoid conscious or subconscious bias

Attractive or more cooperative subjectsAttractive or more cooperative subjects–– Avoid investigator convenience Avoid investigator convenience

Closer location have greater chanceCloser location have greater chance

Surveillance depends on reporting from local Surveillance depends on reporting from local levelslevelsBoring work; give it meaningBoring work; give it meaning

Provide incentive to report from the lowest Provide incentive to report from the lowest levels of the systemlevels of the system

Distribute data and analyses to all reporters, Distribute data and analyses to all reporters, so they see how data usedso they see how data usedGive credit by name to encourage reportingGive credit by name to encourage reporting

Provide Provide FFeedback (data flows eedback (data flows both ways)both ways)

Influenza A (H5N1) Influenza A (H5N1) PneumoniaPneumonia

Hien. NEJM 2004;350:1179

SARS epidemicsPatients

Hospitals

Family 1 Family 2 Family 3….…………... Family N

I.C.Failure

Communities

International

9

Dr. Somsak Wattanasri

II. Surveillance System: How it work?II. Surveillance System: How it work?

1. Collection•Record and report

2. Collation: • data analysis

3. Information synthesis

4. Dissemination• timely• action oriented

Weakness

• No action (surveillance for statistics)• No mandate (no receptor)• No funtional epidemiologist (CD4 <200)• No motivation

How to improve Surveillance

Surveillance and Rapid Response Team (SRRT)Surveillance and Rapid Response Team (SRRT)

• Tsunami• Avian influenza• Cholera outbreak• Dengue

ตําบล

จังหวัด

อําเภอ

สวนกลาง

D-SRRT-District

P-SRRT

R-SRRT

C-SRRT

เขต

Surveillance and Rapid Response Team

๑๐๐,๐๐๐ VHVหมูบาน

Intelligence

Control action

Information

1. New virus found

2. Human at risk

3. Human infection or inefficient H2H

4. Confine easy H2H transmissionConfine easy H2H transmission

5. multiple outbreak

6 multi-countriesInfluenza Pandemic

“SRRT ” 1030Surveillance andRapid Response

Team

Health services

SRRTs

AI provincial Team (Human and Animal)

MoPH assigned “Mr. Bird Flu”

(800,000 village health volunteers & community leaders)

Lay report

Governor

NetworkNetwork

• History screening at all hospital• Testing of respiratory specimen • Survey of village and identify exposure• Active case finding and monitor

household member for 10 days• Antiviral prophylaxis for family member

of confirm H5 cases• Culling of affected poultry• Educated villagers to avoid risk

Hospital (SRRT)

Laboratory

Veterinarian

Pathologists

Early pandemicAlert phase 4

Ro = 1.5 - 2

Operational criteria for action:“5 or more cases within 10 days”

• Epidemiological linkage• Human-to-human• Evidence of viral change

• Isolation & treat• Antiviral prophylaxis

for all contacts• Stop work /class

in affected area

Types of exercise:

•Table-top

•Drills

•Full-scale exercise

•Etc.

Exercise the planExercise the plan

Operation levels:National/ CentralProvincialLocal

16 A

pr 0

5

Global preparedness

National preparedness

National preparedness

Regional preparedness

Regional preparedness

National preparedness

Thailand’s preparedness

Influenza A (H1) outbreak at Samutsakorn

• 1700 workers• ILI 180• stop work• Isolated dormitory• Daily temperature

Evaluation of surveillance systemEvaluation of surveillance system

• clear• unclear • institution

• functional• staff• skill• equipment• funding

• information ( timely & action oriented)• investigation• implementation

• public health practice

• morbidity• mortality• policy

MandateMandate StructureStructure

InputInput

OutputOutputImpactImpact

ConclusionConclusion

1. Surveillance to safeguard the people2. Start with priority disease reporting3. Timeliness is most crucial4. Detection of outbreak5. Investigation to know the cause

BackgroundBackground1913 Dr. 1913 Dr. SujartiSujarti initiated a initiated a surveillance projectsurveillance project

1934 Established a C.D Law 1934 Established a C.D Law

1970 1970 EstablisedEstablised an an Epidemiological Surveillance Epidemiological Surveillance for reporting 14 infectious for reporting 14 infectious diseases diseases

1972 1972 InstitutionalisedInstitutionalised the the Division of Epidemiology Division of Epidemiology (DOE)(DOE)

Now BOE set for 70 diseases Now BOE set for 70 diseases to be reported weeklyto be reported weekly

BackgroundBackground

ObjectivesObjectives

To monitor trends of diseases and illnessTo monitor trends of diseases and illness

To detect outbreak of diseases and illnessTo detect outbreak of diseases and illness

To describe epidemiological information and risk To describe epidemiological information and risk

factors of health problemsfactors of health problems

To recommend effective prevention and control To recommend effective prevention and control

measuresmeasures

Current Epidemiological Surveillance Current Epidemiological Surveillance

Systems in ThailandSystems in ThailandDiseases Surveillance SystemDiseases Surveillance System:: 506506 Report Report ((MainMain))

HIVHIV//AIDS Surveillance SystemAIDS Surveillance System:: 506/1506/1 ReportReport

Injury SurveillanceInjury Surveillance:: ISIS

Occupational Occupational && Environmental Surveillance System Environmental Surveillance System

((still pilot projectstill pilot project))

Current Diseases Surveillance Systems in Current Diseases Surveillance Systems in

ThailandThailandDiseases Surveillance Diseases Surveillance (506(506 Reporting SystemReporting System):):

mostly mostly clinically diagnosed andclinically diagnosed and reportreporteded since since 19721972

(30(30 yearsyears))

Acute Flaccid Paralysis Acute Flaccid Paralysis ((AFPAFP):): since since 19971997 based on based on

506506 reporting system supplement with reporting system supplement with

strengtheningstrengthening,, investigation and investigation and 6060--days followdays follow--up up

systemsystem

Network of Epidemiological Report in Thailand

Ministry of Public Health

Department of Disease Control

Bureau of Epidemiology

Provincial Health Office

District Center of Epidemiological Information

Office of Disease Control

and Prevention 1-12

Subdistrict Center of Epidemiological Information

CUP

Reporting Unit in Health Insurance Project

CUS, CUT

Reporting Unit outside the Health Insurance System

WHO

SectionSection ofof SurveillanceSurveillance andandInvestigationInvestigation

1. Detect abnormal health events and outbreak in country and outside.

2. Verify outbreak and follow the outbreak situation through the responsible organization.

3. Investigate the complicated outbreak which needs epidemiological expertise.

4. Analyze health situation and conduct recommendation to prevent and control.

5. Perform executive summary of health situation for administors and responsible units by weekly.

Example for Example for 506506 Reporting Reporting SystemSystem

Diseases ClassificationDiseases ClassificationFWBDFWBDVPDVPDVectorVector--borne Diseasesborne DiseasesZoonosisZoonosisCNS Infectious DiseasesCNS Infectious DiseasesRespiratory Infectious DiseasesRespiratory Infectious DiseasesContactContact,, EIDsEIDs and other infectious and other infectious diseasesdiseasesOthers nonOthers non--infectious diseasesinfectious diseases

Food Food && WaterWater--Borne Infectious DiseasesBorne Infectious Diseases

Acute DiarrheaAcute Diarrhea

Severe DiarrheaSevere Diarrhea

Enteric FeverEnteric Fever

Food PoisoningFood Poisoning

DysenteryDysentery

HepatitisHepatitis:: AA,, BB,, CC,, DD,, EE,, GG,, unspecifiedunspecified

HFMDHFMD

Vaccine Preventable Diseases Vaccine Preventable Diseases ((VPDVPD))

AFPAFP

MeaslesMeasles

RubellaRubella

ChickenpoxChickenpox

MumpsMumps

TetanusTetanus,, Neonatal tetanusNeonatal tetanus

VectorVector--borne Diseasesborne Diseases

Dengue FeverDengue Fever// Dengue Dengue HemorrhagicHemorrhagic FeverFever//DSSDSS

MalariaMalaria

ChikungunyaChikungunya

Lymphatic Lymphatic FilariasisFilariasis

Scrub TyphusScrub Typhus

ZoonosisZoonosis

AnthraxAnthrax

LeptospirosisLeptospirosis

RabiesRabies

TrichinosisTrichinosis

MelioidosisMelioidosis

CNS Infectious DiseasesCNS Infectious Diseases

MeningococcalMeningococcal MeningitisMeningitis

EncephalitisEncephalitis:: JEJE,, othersothers

Respiratory Infectious DiseasesRespiratory Infectious Diseases

InfluenzaInfluenza

TBTB

PneumoniaPneumonia

LegionnaireLegionnaire’’s Diseases Disease

Contact Infectious Diseases and Emerging Contact Infectious Diseases and Emerging

Infectious DiseasesInfectious Diseases

FUOFUO

YawsYaws

LeprosyLeprosy

Viral ConjunctivitisViral Conjunctivitis

STDsSTDs

EIDsEIDs:: Avian InfluenzaAvian Influenza,, vCJDvCJD,, NipahNipah virusvirus,, HFMDHFMD,,BioterrismBioterrism etcetc

0

5

10

15

20

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Rat

e pe

r 10

0,00

0 P

op.

Reported Cases of Leptospirosis per Reported Cases of Leptospirosis per 100,000100,000

PopulationPopulation,, ThailandThailand,, 19901990--1999.1999.

43

5 2 35 14149

22

960

102

1540

228

1105

271

714

212397

113 15754

0

300

600

900

1200

1500

1800

Nu

mbe

r of

Cas

es

0-4 5-9 10-14 15-24 25-34 35-44 45-54 55-64 65+

MaleFemale

Reported Cases of Reported Cases of LeptospirosisLeptospirosisby Ageby Age--Group and SexGroup and Sex,, ThailandThailand,, 19991999

5 2 35 14149

22

960

102

1540

228

1105

271

714

212397

113 15754

0

300

600

900

1200

1500

1800

Nu

mbe

r of

Cas

es

0-4 5-9 10-14 15-24 25-34 35-44 45-54 55-64 65+

MaleFemale

Reported Cases of Reported Cases of LeptospirosisLeptospirosisby Ageby Age--Group and SexGroup and Sex,, ThailandThailand,,

19991999

Number of Number of leptospirosisleptospirosispatients by date of onsetpatients by date of onset

duringduring NovNov.. 2525 -- DecDec.. 15,15, 2000.2000.

12

19

2526

11 1 7 8 116

1 1

6

1 10

5

10

15

20

25

30

35

40

19/1

1/43

21/1

1/43

23/1

1/43

25/1

1/43

27/1

1/43

29/1

1/43

1604

1

1604

3

1604

5

1604

7

1604

9

1605

1

1605

3

15/1

2/43

Date of onset

Num

ber

of p

atie

nt

Confirmed case Suspected case

Flood

Investigation