title: The Critical Role of Early Dengue Surveillance and Limitations of Clinical Reporting - Implications for Non-Endemic Countries.
abstract: The increasing dengue burden and epidemic severity worldwide have highlighted the need to improve surveillance. In non-endemic areas such as Taiwan, where outbreaks start mostly with imported cases from Southeast Asia, a closer examination of surveillance dynamics to detect cases early is necessary. To evaluate problems with dengue surveillance and investigate the involvement of different factors at various epidemic stages, we investigated 632 laboratory-confirmed indigenous dengue cases in Kaohsiung City, Taiwan during 2009-2010. The estimated sensitivity of clinical surveillance was 82.4% (521/632). Initially, the modified serological surveillance (targeting only the contacts of laboratory-confirmed dengue cases) identified clinically unrecognized afebrile cases in younger patients who visited private clinics and accounted for 30.4% (35/115) of the early-stage cases. Multivariate regression indicated that hospital/medical center visits [Adjusted Odds Ratio (aOR): 11.6, 95% confidence interval (CI): 6.3-21.4], middle epidemic stage [aOR: 2.4 (1.2-4.7)], fever [aOR: 2.3 (2.3-12.9)], and musculo-articular pain [aOR: 1.9 (1.05-3.3)] were significantly associated with clinical reporting. However, cases with pruritus/rash [aOR: 0.47 (0.26-0.83)] and diarrhea [aOR: 0.47 (0.26-0.85)] were underreported. In conclusion, multiple factors contributed to dengue surveillance problems. To prevent a large-scale epidemic and minimize severe dengue cases, there is a need for integrated surveillance incorporating entomological, clinical, serological, and virological surveillance systems to detect early cases, followed by immediate prevention and control measures and continuous evaluation to ensure effectiveness. This effort will be particularly important for an arbovirus, such as Zika virus, with a high asymptomatic infection ratio. For dengue- non-endemic countries, we recommend serological surveillance be implemented in areas with high Aedes mosquito indices or many breeding sites. Syndromic surveillance, spatial analysis and monitoring changes in epidemiological characteristics using a geographical information system, as well as epidemic prediction models involving epidemiological, meteorological and environmental variables will be helpful for early risk communication to increase awareness.
authors: Department of Medicine (Med.), College of Med., National Taiwan University (NTU), Taipei, Taiwan (100), Republic of China (R.O.C.).
authors: Jui-Hung
authors: JH
authors: Kao
authors: Department of Health, Kaohsiung City Government, Kaohsiung, Taiwan (802), R.O.C.
authors: Chaur-Dong
authors: CD
authors: Chen
authors: Institute of Epidemiology and Preventive Med., College of Public Health, NTU, Taipei, Taiwan (100), R.O.C.
authors: Zheng-Rong
authors: ZR
authors: Tiger Li
authors: Research Center for Humanities & Social Science, Academia Sinica, Taipei, Taiwan (115), R.O.C.
authors: Ta-Chien
authors: TC
authors: Chan
authors: Institute of Epidemiology and Preventive Med., College of Public Health, NTU, Taipei, Taiwan (100), R.O.C.
authors: Tsung-Hwa
authors: TH
authors: Tung
authors: Department of Medicine (Med.), College of Med., National Taiwan University (NTU), Taipei, Taiwan (100), Republic of China (R.O.C.).
authors: Ying-Hsia
authors: YH
authors: Chu
authors: Department of Pediatrics, NTU Hospital, Taipei, Taiwan (100), R.O.C.
authors: Hau-Yuan
authors: HY
authors: Cheng
authors: Division of Infectious Diseases, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University Medical College, Kaohsiung, Taiwan (833), R.O.C.
authors: Jien-Wei
authors: JW
authors: Liu
authors: Department of Emergency Medicine, NTU Hospital, Taipei, Taiwan (100), R.O.C.
authors: Fuh-Yuan
authors: FY
authors: Shih
authors: Department of Health, Taiwan Centers for Disease Control (Taiwan CDC), Taipei, Taiwan (100), R.O.C.
authors: Pei-Yun
authors: PY
authors: Shu
authors: Department of Health, Taiwan Centers for Disease Control (Taiwan CDC), Taipei, Taiwan (100), R.O.C.
authors: Chien-Chou
authors: CC
authors: Lin
authors: Department of Health, Kaohsiung City Government, Kaohsiung, Taiwan (802), R.O.C.
authors: Wu-Hsiung
authors: WH
authors: Tsai
authors: Institute of Immunology, College of Medicine, NTU, Taipei, Taiwan (100), R.O.C.
authors: Chia-Chi
authors: CC
authors: Ku
authors: Department of Health, Kaohsiung City Government, Kaohsiung, Taiwan (802), R.O.C.|Department of Public Health, Kaohsiung Medical University, and Dept. of Occupational and Environmental Med., Kaohsiung Medical University Hospital, Kaohsiung, Taiwan (807), R.O.C.
authors: Chi-Kung
authors: CK
authors: Ho
authors: Institute of Epidemiology and Preventive Med., College of Public Health, NTU, Taipei, Taiwan (100), R.O.C.
authors: Chwan-Chuen
authors: CC
authors: King
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000175:diagnosis* / Q000453:epidemiology* / Q000635:transmission; D003716:Dengue Virus / Q000302:isolation & purification*; D004196:Disease Outbreaks; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D042241:Early Diagnosis; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult