24/08/2016. Developing Early Warning System for Dengue Control in Singapore. Dengue cases increasing globally

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1 24/8/216 Dengue cases increasing globally Developing Early Warning System for Dengue Control in Singapore Ng Lee Ching Environmental Health Institute 19 August 216 Cases across the Americas, South-East Asia and Western Pacific exceeded 3 million in 213. Disease burden Population at Risk Endemic countries Infections/yr Severe Dengue Numbers 3.9 billion million 2.1 million Deaths/year Integrated Dengue Management Suppression of mosquito vectors through source reduction (and space spray in transmission area) Infectious Disease Act Control of Vectors and Pesticides Act EPH (Environmental Control Officers) Regulations Legislations Surveillance, Research and Risk Assessment Communication and messaging Public Education and mobilisation Education Incidence rates per 1, Increasing dengue incidence rates in Singapore - despite low Aedes house index : Vector control programme 1969 Keep Singapore c lean & mosquito free campaign 1974: 75% of urban slums cleared (HDB) 1998: Control of Vector & Pestic ide Ac t 26: Early warning system and risk stratification 26, dedicated mosquito control programme in TCs Year Aedes house index: number of premise with mosquito breeding, among 1 checked Aedes house index ( ) Dengue7/ CM H/

2 24/8/216 Outcome of dengue control: - Declining prevalence of dengue antibodies in each age group Percentage of cohort with Dengue specific anti body Reduced probability of an immuno-naïve individual acquiring a dengue infection Reduction in sero-prevalence across age group 1 Reduced Force of Infection sustained % seropositives 8 6 Older adults ( 41 yrs) 4 Adult (2 yrs) 2 Youth ( 2 yrs) Age (years) at 213 Year of survey Seroprevalence rate among Singapore residents continue to fall in the last decades, and youth stabilise at about 16% Challenges in our current dengue control programme Alert System Needed for Preemptive Actions Control Prevention Mosquito Surveillance and control Dense population >7/ sqkm Continued urbanization Low herd immunity Highly diverse and rapidly evolving DENVs Presence of Aedes aegypti, Case Virus Early notification Surveillance Cluster Cluster management Ea rl y L a u n c h o f mo z z i e c a mp a i g n Outbreak Increase in travel efficiency (international and domestic) Global City No effective vaccine Forecast and risk stratification Protection People 2

3 24/8/216 o current cases predicted cases Utility of temporal forecast model for planning and preparedness - Risk comms and resource management Launch of dengue campaign (28 Apr) 1 st media report on possible dengue outbreak (ST 7 Apr) 3

4 24/8/216 Using Big Data Analytics Dengue spatial-temporal model for risk forecast coming soon! Climate data Vector data Ø Temperature Ø Absolute humidity ØBreeding index ØGravitrap index Population demography Model Satellite data Ø Vegetation index Infrastructure data Ø Age of buildings Ø No. of units Case data Ø Weekly dengue cases Integrated Dengue Surveillance for Decision Support Virus Serotype surveillance Rapid Operational Response Time Early warning of Outbreak Targeted Response Risk Assessment Case Virus Vector Ecology Immatures: Lab Diagnostics Temporal and Spatial distribution of serotype Weather paramters Disease Notification system Evaluation and development of new tools Detect emergence of new genotypes Premise check for breedings Adults: Gravitrap s surveillance Insecticide Resistance Population density Age of buildings Extent of urbanisation Jan 12 (n=42) Feb 12 (n=38) Mar 12 (n=49) Apr 12 (n=124) May 12 (n=119) Jun 12 (n=148) Jul 12 (n=161) Aug 12 (n=131) Sep 12 (n=14) Oct 12 (n=153) N ov 12 (n=12) Dec 12 (n=136) Jan 13 (n=373) Feb 13 (n=326) Mar 13 (n=476) Apr 13 (n=842) May 13 (n=134) Jun 13 (n=1254) Jul 13 (n=735) Aug 13 (n=594) Sep 13 (n=646) Oct 13 (n=746) N ov 13 (n=587) Dec 13 (n=637) Jan 14 (n=55) Feb 14 (n=321) Mar 14 (n=31) Apr 14 (n=47) May 14 (n=611) Jun 14 (n=947) Jul 14 (n=133) Aug 14 (n=754) Sep 14 (n=529) Oct 14 (n=361) N ov 14 (n=29) Dec 14 (n=258) Jan 15 (n=36) Feb 15 (n=24) Mar 15 (n=131) Apr 15 (n=166) May 15 (n=23) Jun 15 (n=292) Jul 15 (n=382) Aug 15 (n=296) Sep 15 (n=34) Oct 15 (n=351) N ov 15 (n=332) Dec 15 (n=578) Jan 16 (n=912) Feb 16 (n=7) Mar 16 (n=543) Apr 16 (n=352) May 16 (n=338) Jun 16 (n=286) Jul 16 (n=316) Aug 16 (n=22) Risk Stratification Percentage of cases 9 DENV4 DENV3 DENV1 DENV2 MOH data from GPs, polyclinics and hospitals; plotted based on onset dates- Updated as of 12 August 216 Low sample size 4

5 24/8/216 Switches in predominant serotype precede outbreaks Outbreaks associated with Switch in predominant serotype 1 9 Dengue cases 4-week moving average (D2) DENV2 to 1 4-week moving average (D1) 4-week moving average (D3) 1 9 outbreak DENV-2 outbreak Increased DENV-2 cases outbreak Percentage of distribution DENV1 to Total case count Emergence of new virus lineages Year/ EW Serotype switch to Genotype I Serotype switch to DENV-2 and clade replacement Threat of Serotype switch to Emergence of Genotype III Serotype switch to Genotype III Gravitrap sentinel surveillance (more than 3 traps) Association of Gravitrap aegypti index and cases r =.5 Gravitrap aegypti index (%) 18% 16% 14% 12% 1% 8% 6% 4% 2% % Cases Gravitrap aegypti index 4 weeks moving average E-week EW31 Weekly data from 34 sentinel sites Dengue cases Gravitrap aegypti index (%) r =.67 14% 1 12% 1% 8% 6% 4% 2% % Cases Gravitrap aegypti index E-week Dengue cases 5

6 24/8/216 Sites at risks are associated with more cases (Odd Ratio = 6.7, P =.1) Vertical distribution of Aedes mosquitoes in all sentinel sites - Consistently more at lower floors Low risks Moderate to high risks Aug 13 to Mar 14 Apr 14 to Sep 14: Oct 14 to Apr 15 3 Serangoon Central/ Lor Liew Lian 25 Pasir Ris Dr 4/6 Total no. of cases Toa Payoh Lor 4/5 Yishun St 11 Bedok North St 2 West Coast Rd HDB Floor 5 Woodlands St 13.% 5.% 1.% 15.% 2.% Compassvale St/Rd Mean Gravitrap aegypti index Mean m osquitoes per site per tr ap per week Ae. albopictus Mean m osquitoes per site per tr ap per week Ae. albopictus.2.4 Mean m osquitoes per site per tr ap per week Ae. albopictus Bukit Batok St 31 Canberra Rd 21 Guide and prioritise inspection 22 2 of 58 blocks (.3%) had more Aedes aegypti at middle floors indoor breeding Integrated Dengue Surveillance for Decision Support Block at Woodlands St 13 Block at Yishun St 21 HDB floor Mean mosquitoes per trap per week HDB floor Mean mosquitoes per trap per week Rapid Operational Response Time Early warning of Outbreak Risk Stratification Targeted Response Risk Assessment Similar number of at low and middle floors HDB floor Block at Simei St Mean mosquitoes per trap per week 23 Case Lab Diagnostics Disease Notification system Evaluation and development of new tools Virus Temporal and Spatial distribution of serotype Detect emergence of new genotypes Vector Immatures: Premise check for breedings Adults: Gravitrap s surveillance Insecticide Resistance Ecology Weather paramters Population density Age of buildings Extent of urbanisation 6

7 24/8/216 Enhanced approach for dengue surveillance and control since 25 Exploring the use of male Wolbachia-Aedes for suppression of population in Singapore Inter-epidemic surveillance and control Whole-year-round preventive action Integrated surveillance to guide decision making Risk based prevention and intervention Risk assessment and stratification Optimisation of resources and preparedness Coordinated intersectoral cooperation Whole of government approach 3P- Private, People and Public 26 Acknowledgement Data, analysis and research: i. Prof Goh Kee Tai epidemiologist, previously MOH ii. Dr Jeffery Cutter Dir, MOH iii. Prof Chan Kai Lok entomologist, previously NEA iv. Ms Wong Chin Ling DGMS, and team v. Mr Tony Teo, Dir EPHO, NEA vi. Dr Alex Cook, Mathematician, NUS vii. Dr Wilson Tan and team Entomologist, EHI, NEA viii. Grace Yap and team Epidemiologist, EHI, NEA ix. Dr Chong Chee Seng and team entomologist EHI, NEA x. Dr Chanditha and team molecular microbiologist, EHI, NEA xi. Dr Tan Li Kiang and team immunologist, EHI, NEA Strong support: i. Mr Khoo Seow Poh DCEO, NEA ii. Mr Derek Ho- DGPH, NEA 7

8 24/8/216 Safeguard Nurture Cherish 8