surveillance , disease control and prevention for chikungunya fever thailand, 2008-2009

Surveillance , Disease Control Surveillance , Disease Control and Prevention for and Prevention for Chikungunya FeverChikungunya FeverThailand, 2008-2009 Thailand, 2008-2009

Rome Buathong, MD., FETP.

Central Epidemiological Investigation and Surveillance

Bureau of Epidemiology

Thailand-Ministry of Public Health

BUREAU OF EPIDEMIOLOGY-Ministry of Public Health (MOPH),

THAILAND

Arthropod-borne viral arthritis and rashArthropod-borne viral arthritis and rash syndromesyndrome consist of consist of – Chikungunya virus diseaseChikungunya virus disease– Mayaro virus disease Mayaro virus disease – Sindibis virus diseaseSindibis virus disease– O’nyong-nyong Fever: less arthritisO’nyong-nyong Fever: less arthritis

Chikungunya virus disease เป็�น RNA virus จั�ดอยู่��ใน Alphavirus gunus, Togaviridae family

Chikungunya Infection

Three strains were distinguishedThree strains were distinguished– East/Central African StrainEast/Central African Strain

– West African StrainWest African Strain

– Asian StrainAsian Strain

Aedes aegypti Aedes aegypti ((ยุ�งลายุบ้�านยุ�งลายุบ้�าน)), Aedes , Aedes albopictus albopictus ((ยุ�งลายุสวนยุ�งลายุสวน) ) are main are main vectorvector

Chikungunya Infection

East/Central African Strain

West African Strain

Asian Strain

Singapore (Jan 08) 200

Malaysia

(Sep 08) 2,000

India,~1,500,000

cases

Report ~200 death cases

BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND

1976 Prachinburi

1958, First identified in

Bangkok

1988 Surin

1991 Khon Khean

1993 Loei, Phrayao

1995 Nongkhai(94), Nakhon Si Thammarat(576)

History of Chikungunya Fever in Thailand

Chikv strain identified in 1962-1995 was all Asian strain (AFRIMS)

Yi-ngo

อ.ยู่��งอ

In October, 2008

Cluster of fever , rash and severe arthralgia was detected in one village at Laharn health center and then chikungunya was suspected

After investigation among 82 suspected case revealed positive Chikungunya by RT-PCR and seroconversion by HI (60%)

BackgroundBackgroundSince Chikungunya fever was not a notifiable Since Chikungunya fever was not a notifiable

disease in Thailand, thus the Bureau of disease in Thailand, thus the Bureau of Epidemiology included Chikungunya fever is Epidemiology included Chikungunya fever is the latest notifiable diseasethe latest notifiable disease and launched in and launched in November 2008 (passive surveillance November 2008 (passive surveillance nationwide; all gov. hospitals and some private)nationwide; all gov. hospitals and some private)

Three case definitions were described as Three case definitions were described as suspected, probable and confirmed suspected, probable and confirmed

All suspected cases required to retrospective All suspected cases required to retrospective report to the national surveillance systemreport to the national surveillance system

BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND

Case DefinitionsCase Definitions Suspected Case:Suspected Case:

Fever with at least two of the following symptomsFever with at least two of the following symptoms1.1. Arthralgia/Arthritis/Joint swellingArthralgia/Arthritis/Joint swelling

2.2. RashRash

3.3. MyalgiaMyalgia

4.4. HeadacheHeadache

5.5. Retro-orbital painRetro-orbital pain

Probable Case:Probable Case: suspected case with suspected case with 1) PLT normal and WBC < 5000 or1) PLT normal and WBC < 5000 or

2) Epi-linkage with confirmed case2) Epi-linkage with confirmed case

Confirmed Case:Confirmed Case: suspected case with suspected case with CHIKV CHIKV laboratory confirmed by PCR, HI a/o IgMlaboratory confirmed by PCR, HI a/o IgM


Protocol for Lab TestingProtocol for Lab Testing


A Suspected Chikungunya Fever

Epidemic area

Chikungunya ( NIH)1.RT PCR ( onset < 5 days)2.HI ( 2-3 weeks a part)Dengue(NIH)1.HI ( 2-3 weeks a part)

Other area

Same as epidemic areaPLUS1. Measles IgM (NIH)2. Rubella IgM (NIH)

Entomology

Mosquito trapping:Human base technique

Aspirator technique

Isolated CHIKV: at AFRIM and NIHMolecular sequencing: at AFRIM and NIH(both human & mosquito)Identified Aedes spp.: at AFRIM and NIH

Surveillance ResultsSurveillance ResultsBy By March 10March 10thth, 2009, 2009, totally , totally 12,11512,115

suspected casessuspected cases were reported to the were reported to the passive surveillance system with passive surveillance system with no death no death casecase

Male : female ratio Male : female ratio was 1:1.5was 1:1.5Adult cases was Adult cases was 86%86%Median age was Median age was 38 years38 years ( (IQR: 23, 50IQR: 23, 50))The main occupation was agricultural (The main occupation was agricultural (47%47%) ) The OPD:IPD:Active cases ratio was The OPD:IPD:Active cases ratio was 15:1:1 15:1:1


Number of Cases by Date of Onset, Chikungunya Fever, Number of Cases by Date of Onset, Chikungunya Fever,

ThailandThailand August 2008-March 2009August 2008-March 2009


0

50

100

150

200

250

300

350

400

8/11

/200

8

8/25

/200

8

9/8/

2008

9/22

/200

8

10/6

/200

8

10/2

0/200

8

11/3

/200

8

11/1

7/200

8

12/1

/200

8

12/1

5/200

8

12/2

9/200

8

1/12

/200

9

1/26

/200

9

2/9/

2009

2/23

/200

9

Date of Onset

Number

N=12,115X-sectional serosurvey was conducted in one village (n=521)

•26% seropositive by IgM (≥40 units) & HI (≥1:40),

•10% Asymptomatic infection,

•Adult spec. AR = 29% vs Children spec. AR=7% (p<0.001)

0

50

100

150

200

250

Date of Onset

Number

0

10

20

30

40

50

60

Onset

Number

0

10

20

30

40

50

60

Onset

Number

Narathiwat,

6371 cases

890/100,000 pop.

Pattani, 1612 cases

251/100,000 pop.

Yala, 488 cases

103/100,000 pop.

Songkhla, 3629 cases

272/100,000 pop.

0

10

20

30

40

50

60

Onset

Number

Aug 11th ,08

0

10

20

30

40

50

60

Onset

Number

Sep 10th ,08

0

5

10

15

20

25

Onset

Number

Oct 12th ,08

020406080

100120140160180200

Onset

Number

Nov 1st ,08

Laboratory Results Laboratory Results


Totally 1,009 cases were sent for laboratory testing for CHIKV (Jan 31st, 09)

492 cases were laboratory confirmed (48.8%) either RT-PCR or sero-conversion for HI (four-fold rising)

The yield of RT-PCR for CHIKV was 58.0%(457/788) and sero-conversion HI was 47.9% (114/238)

Dengue was positive 4.3% (43/1009)


Chikungunya Suspected

Confirmed Chikungunya Fever50%

Dengue4%

Rubella<1%

Measles<1%

Entomology Entomology


Aedes albopictus and Ae. aegypti were identified in epidemic setting of deep southern part of Thailand

CHIKV was isolated by PCR in both species of Aedes spp.

Molecular sequencing is pending


SRRT, 1030 nation wide

Within 24 hr,

Early control and containment

PCR/IgM

Prevention & Control StrategiesPrevention & Control Strategies


Early detection – clinical criteria and laboratory testing especially in new area

Early investigation and control immediately National campaign for mosquito larva

eradication (as much as possible) Health education

Nationwide: TV, internet, printing mediaLocal: community radio


Contagious spreading as a majority

Sporadic cases were detected in non-epidemic area

All cases associated with southern epidemic area

Imported by travelers; students, military recruits

No sustainable local transmission

Active surveillance in nursing colleges, military units, transportation terminals in BKK

East/Central African Strain

Islands in Indian Ocean, India,

Srilangka, Malaysia, Thailand 2008-2009

Mutation of E1 gene at Position 226 change from

Alanine to Valine ( 226 A 226V)

Molecular Sequencing of Chikungunya virus in humanMolecular Sequencing of Chikungunya virus in human

E1 226V

Update Laboratory DiagnosisUpdate Laboratory Diagnosis

NIH NIH – HI titer : 4-fold rising in pairedHI titer : 4-fold rising in paired– Rapid test IgM: no longer interpretationRapid test IgM: no longer interpretation– IgM will be available in OD cut pointIgM will be available in OD cut point– PCR ( only RT) is the bestPCR ( only RT) is the best– Viral isolation Viral isolation Sequencing Sequencing

AFRIMAFRIM– PCR ( RT, Nested and real time) PCR ( RT, Nested and real time) sequencing sequencing – IgM by ELISA ( unit) : > 40 unitsIgM by ELISA ( unit) : > 40 units– HI titer HI titer – Virus isolationVirus isolation

Significant Finding in Significant Finding in Serosurvey Study at Village no Serosurvey Study at Village no 8, Laharn Sub-district, Yi-Ngor 8, Laharn Sub-district, Yi-Ngor

District, Narathiwat 2008District, Narathiwat 2008

Pisittawoot Ayood, MD. FETP.Pisittawoot Ayood, MD. FETP.Bureau of EpidemiologyBureau of EpidemiologyDepartment of Disease Department of Disease

ControlControlMinistry of Public HealthMinistry of Public Health

ResultsResults

Overall survey 698 people (~ 750 pop)Overall survey 698 people (~ 750 pop)Totally 480 people were blood drawn Totally 480 people were blood drawn Blood testing for IgM and HI at AFRIM and NIH Blood testing for IgM and HI at AFRIM and NIH – IgM ≥ 40 units => Acute infectionIgM ≥ 40 units => Acute infection– HI titer ≥ 1:40 => Recent infectionHI titer ≥ 1:40 => Recent infection

Totally 117 cases was met seropositive criteria Totally 117 cases was met seropositive criteria (24.4%)(24.4%)Median age: 53 years, Range (4-87), IQR (43-Median age: 53 years, Range (4-87), IQR (43-65) 65) Number of children case was only 6 (5%)Number of children case was only 6 (5%)Male : female ratio was 1:1 (58:59)Male : female ratio was 1:1 (58:59)

Symptom Vs. Asymptom in Symptom Vs. Asymptom in Confirmed Chikungunya InfectionConfirmed Chikungunya Infection

67%

33%

Symptom

Asymptom

N=117

Clinical Presentation of Symptomatic Confirmed Clinical Presentation of Symptomatic Confirmed Chikungunya InfectionChikungunya Infection

1.3

14.1

39.7

43.6

64.1

76.9

83.3

84.6

91

0 10 20 30 40 50 60 70 80 90 100

Symptom

%

N = 78

Clinical Case Definition compare to Laboratory Clinical Case Definition compare to Laboratory Confirmed Chikungunya Infection as a Gold Confirmed Chikungunya Infection as a Gold

StandardStandard

Case Case DefinitionDefinition

Fever +Fever +

1 Clinical 1 Clinical

Fever +Fever +

2 Clinical2 Clinical

Any +Any +

3 Clinical3 Clinical

SensitivitySensitivity 76.5%76.5% 54.7%54.7% 79.0%79.0%

SpecificitySpecificity 88.1%88.1% 95.3%95.3% 87.6%87.6%

Predictive Value Predictive Value PositivePositive (PVP)(PVP) 60.7%60.7% 79.0%79.0% 58.1%58.1%

Predictive Value Predictive Value Negative (PVN)Negative (PVN) 93.9%93.9% 86.7%86.7% 95.1%95.1%

Clinical Presentation of Symptomatic Clinical Presentation of Symptomatic Confirmed Chikungunya InfectionConfirmed Chikungunya Infection

Among 78 symptomatic confirmed casesAmong 78 symptomatic confirmed cases

– Fever + joint symptom (pain or swelling):Fever + joint symptom (pain or swelling):79.5%79.5%– Fever + joint pain: Fever + joint pain: 78.2%78.2%– Fever + rash: Fever + rash: 57.7%57.7%– Fever + joint symptom + rash: Fever + joint symptom + rash: 52.6%52.6%

Conclusion Conclusion


The re-emerging Chikungunya fever is confirmed after the 13-year absence with new strain

The outbreak tends to spread out in the adjacent provinces (one month apart)

Few confirmed cases were reported from other parts of the country (with related to southern area)

The vector control measures were limited in this complicated situation area with high density of both species of Aedes mosquito circulation

The major interventions include early case detection by clinical criteria and then laboratory testing with PCR, rapid investigation and implementation of control measures

Contributions Contributions


Department of Disease ControlDepartment of Medical SciencesDepartment of Medical ServicesOffices of Permanent SecretaryMedical Schools/UniversitiesRoyal College of Physician and Pediatrics of

ThailandMinistry of DefenseAFRIMS

MOPH


SAWASDEE

THAILAND

Thank you for your attentionThank you for your attention

surveillance , disease control and prevention for chikungunya fever thailand, 2008-2009

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