Correction: The Critical Role of Early Dengue Surveillance and Limitations of Clinical Reporting - Implications for Non-Endemic Countries.

[This corrects the article DOI: 10.1371/journal.pone.0160230.].

The Critical Role of Early Dengue Surveillance and Limitations of Clinical Reporting - Implications for Non-Endemic Countries.

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.

Dengue fever scoring system: new strategy for the early detection of acute dengue virus infection in Taiwan.

BACKGROUND/PURPOSE: Dengue fever is an important public health problem in Southern Taiwan. The purpose of this study was to develop a dengue scoring system using a three-stage process, which may be used as a guidance tool for the early diagnosis of dengue fever. METHODS: A retrospective study was conducted to identify factors useful for the early diagnosis of dengue fever. We assessed the clinical and laboratory features of 89 adult patients with dengue from 2002 to 2004 at a community-based hospital. They were compared with 14 patients with scrub typhus, 104 with Q fever, and 35 with murine typhus, which might present similar symptoms and signs as dengue infection. A scoring system was designed after analysis of the retrospective study and with the assistance of 10 expert clinicians. For the second stage, we evaluated efficiency in differentiating dengue fever from Q fever, scrub typhus and murine typhus in three hospitals from 2002 to 2005. For the third stage, we prospectively used the dengue scoring system for 498 cases that clinically were suspected as having dengue infection in the city of Kaohsiung from January 2006 to September 2006. RESULTS: The performance of the scoring system was 88.1% sensitivity, 94.9% specificity, 95.7% positive predictive value (PPV), and 86.1% negative predictive value (NPV). Evaluation of the scoring system at the third stage revealed 90.7% sensitivity, 86.9% specificity, 81.4% PPV, and 93.6% NPV. CONCLUSION: The dengue scoring system had a high NPV that might be helpful in the early diagnosis of dengue fever in adults before laboratory data are available.