surveillance , disease control and prevention for chikungunya fever thailand, 2008-2009
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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
BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND
Protocol for Lab TestingProtocol for Lab Testing
BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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)
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
Chikungunya Suspected
Confirmed Chikungunya Fever50%
Dengue4%
Rubella<1%
Measles<1%
Entomology Entomology
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
SRRT, 1030 nation wide
Within 24 hr,
Early control and containment
PCR/IgM
Prevention & Control StrategiesPrevention & Control Strategies
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND
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
BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND
SAWASDEE
THAILAND
Thank you for your attentionThank you for your attention
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