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

BUREAU OF EPIDEMIOLOGY-Ministry of Public Health (MOPH), THAILAND. Surveillance , Disease Control and Prevention for Chikungunya Fever Thailand, 2008-2009. Rome Buathong, MD., FETP . Central Epidemiological Investigation and Surveillance Bureau of Epidemiology

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

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  1. BUREAU OF EPIDEMIOLOGY-Ministry of Public Health (MOPH), THAILAND Surveillance , Disease Control and Prevention for Chikungunya FeverThailand, 2008-2009 Rome Buathong, MD., FETP. Central Epidemiological Investigation and Surveillance Bureau of Epidemiology Thailand-Ministry of Public Health

  2. Chikungunya Infection • Arthropod-borne viral arthritis and rashsyndrome consist of • Chikungunya virus disease • Mayaro virus disease • Sindibis virus disease • O’nyong-nyong Fever: less arthritis • Chikungunya virus disease เป็น RNA virus จัดอยู่ใน Alphavirus gunus, Togaviridae family

  3. Chikungunya Infection • Three strains were distinguished • East/Central African Strain • West African Strain • Asian Strain • Aedes aegypti (ยุงลายบ้าน), Aedes albopictus (ยุงลายสวน) are main vector

  4. West African Strain East/Central African Strain Asian Strain

  5. India, ~1,500,000 cases Malaysia (Sep 08) 2,000 Singapore (Jan 08) 200 Report ~200 death cases

  6. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND History of Chikungunya Fever in Thailand • 1958, First identified in Bangkok • 1976 Prachinburi • 1988 Surin • 1991 Khon Khean Chikv strain identified in 1962-1995 was all Asian strain (AFRIMS) • 1993 Loei, • Phrayao • 1995 Nongkhai(94), • Nakhon Si • Thammarat(576)

  7. 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%) Yi-ngo อ.ยี่งอ

  8. BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND Background • Since Chikungunya fever was not a notifiable disease in Thailand, thus the Bureau of Epidemiology included Chikungunya fever is the latest notifiable disease and launched in November 2008 (passive surveillance nationwide; all gov. hospitals and some private) • Three case definitions were described as suspected, probable and confirmed • All suspected cases required to retrospective report to the national surveillance system

  9. BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND Case Definitions • Suspected Case: Fever with at least two of the following symptoms • Arthralgia/Arthritis/Joint swelling • Rash • Myalgia • Headache • Retro-orbital pain • Probable Case: suspected case with 1) PLT normal and WBC < 5000 or 2) Epi-linkage with confirmed case • Confirmed Case: suspected case withCHIKV laboratory confirmed by PCR, HI a/o IgM

  10. Entomology A Suspected ChikungunyaFever Other area Mosquito trapping: Human base technique Aspirator technique 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) • Same as epidemic area • PLUS • Measles IgM (NIH) • Rubella IgM (NIH) Isolated CHIKV: at AFRIM and NIH Molecular sequencing: at AFRIM and NIH (both human & mosquito) Identified Aedes spp.: at AFRIM and NIH BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND Protocol for Lab Testing

  11. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND Surveillance Results • By March 10th, 2009, totally 12,115suspected cases were reported to the passive surveillance system with no death case • Male : female ratio was 1:1.5 • Adult cases was 86% • Median age was 38 years (IQR: 23, 50) • The main occupation was agricultural (47%) • The OPD:IPD:Active cases ratio was 15:1:1

  12. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND Number of Cases by Date of Onset, Chikungunya Fever, ThailandAugust 2008-March 2009 • X-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) N=12,115

  13. Songkhla, 3629 cases 272/100,000 pop. Pattani, 1612 cases 251/100,000 pop. Sep 10th ,08 Yala, 488 cases 103/100,000 pop. Nov 1st ,08 Narathiwat, 6371 cases 890/100,000 pop. Oct 12th ,08 Aug 11th ,08

  14. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND 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)

  15. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND Dengue 4% Chikungunya Suspected Measles <1% Rubella <1% Confirmed Chikungunya Fever 50%

  16. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND 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 Aedesspp. • Molecular sequencing is pending

  17. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND Within 24 hr, Early control and containment PCR/IgM SRRT, 1030 nation wide

  18. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND Prevention & 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 media • Local: community radio

  19. 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

  20. 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)

  21. Molecular Sequencing of Chikungunya virus in human E1 226V

  22. Update Laboratory Diagnosis • NIH • HI titer : 4-fold rising in paired • Rapid test IgM: no longer interpretation • IgM will be available in OD cut point • PCR ( only RT) is the best • Viral isolation  Sequencing • AFRIM • PCR ( RT, Nested and real time)  sequencing • IgM by ELISA ( unit) : > 40 units • HI titer • Virus isolation

  23. Significant Finding in Serosurvey Study at Village no 8, Laharn Sub-district, Yi-Ngor District, Narathiwat 2008 Pisittawoot Ayood, MD. FETP. Bureau of Epidemiology Department of Disease Control Ministry of Public Health

  24. Results • Overall survey 698 people (~ 750 pop) • Totally 480 people were blood drawn • Blood testing for IgM and HI at AFRIM and NIH • IgM ≥ 40 units => Acute infection • HI titer ≥ 1:40 => Recent infection • Totally 117 cases was met seropositive criteria (24.4%) • Median age: 53 years, Range (4-87), IQR (43-65) • Number of children case was only 6 (5%) • Male : female ratio was 1:1 (58:59)

  25. Symptom Vs. Asymptom in Confirmed Chikungunya Infection N=117

  26. Clinical Presentation of Symptomatic Confirmed Chikungunya Infection N = 78

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

  28. Clinical Presentation of Symptomatic Confirmed Chikungunya Infection • Among 78 symptomatic confirmed cases • Fever + joint symptom (pain or swelling):79.5% • Fever + joint pain: 78.2% • Fever + rash: 57.7% • Fever + joint symptom + rash: 52.6%

  29. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND 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

  30. BUREAU OF EPIDEMIOLOGY-MOPH, THAILAND Contributions • Department of Disease Control • Department of Medical Sciences • Department of Medical Services • Offices of Permanent Secretary • Medical Schools/Universities • Royal College of Physician and Pediatrics of Thailand • Ministry of Defense • AFRIMS MOPH

  31. BUREAU OF EPIDEMIOLOGY- MOPH, THAILAND Thank you for your attention SAWASDEE THAILAND

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