Abstract
ObjectivesTo review the evidence for the application of tools for dengue outbreak prediction/detection and trend monitoring in passive and active disease surveillance systems in order to develop recommendations for endemic countries and identify important research needs.MethodsThis systematic literature review followed the protocol of a review from 2008, extending the systematic search from January 2007 to February 2013 on PubMed, EMBASE, CDSR, WHOLIS and Lilacs. Data reporting followed the PRISMA statement. The eligibility criteria comprised (i) population at risk of dengue, (ii) dengue disease surveillance, (iii) outcome of surveillance described and (iv) empirical data evaluated. The analysis classified studies based on the purpose of the surveillance programme. The main limitation of the review was expected publication bias.ResultsA total of 1116 papers were identified of which 36 articles were included in the review. Four cohort-based prospective studies calculated expansion factors demonstrating remarkable levels of underreporting in the surveillance systems. Several studies demonstrated that enhancement methods such as laboratory support, sentinel-based reporting and staff motivation contributed to improvements in dengue reporting. Additional improvements for passive surveillance systems are possible by incorporating simple data forms/entry/electronic-based reporting; defining clear system objectives; performing data analysis at the lowest possible level (e.g. district); seeking regular data feedback. Six studies showed that serotype changes were positively correlated with the number of reported cases or with dengue incidence, with lag times of up to 6 months. Three studies found that data on internet searches and event-based surveillance correlated well with the epidemic curve derived from surveillance data.ConclusionsPassive surveillance providing the baseline for outbreak alert should be strengthened and appropriate threshold levels for outbreak alerts investigated. Additional enhancement tools such as syndromic surveillance, laboratory support and motivation strategies can be added. Appropriate alert signals need to be identified and integrated into a risk assessment tool. Shifts in dengue serotypes/genotype or electronic event-based surveillance have also considerable potential as indicator in dengue surveillance. Further research on evidence-based response strategies and cost-effectiveness is needed.ObjectifsAnalyser les résultats de l'application d'outils pour la prédiction/détection des épidémies de dengue et la surveillance des tendances dans les systèmes de surveillance active et passive des maladies, afin d’élaborer des recommandations pour les pays endémiques et identifier les besoins importants de recherche.
Highlights
Dengue remains a major and growing public health threat worldwide
Laboratories are required to notify MOH of all patients whose blood samples tested positive for acute dengue infection
-lower herd immunity and -the predominant dengue serotype for 2001–2003 was DEN-2. This was replaced by DEN-1 in June 2004 this strain had been circulating in Singapore since 2002. This change in dengue serotype could have exposed a significant proportion of the population who may be immunologically naive to the new circulating serotype, this is difficult to prove conclusively. -There was no evidence from gene sequencing of the dengue viruses that the epidemic was precipitated by the introduction of a new virulent strain
Summary
Dengue remains a major and growing public health threat worldwide. With the most recent study estimating that global infection rates of 390 million infections occur annually (Bhatt et al 2013), the need for improved dengue surveillance is evident. Dengue surveillance is essential for the detection of outbreaks and, in the longer term, to monitor disease trends. In order to trigger timely interventions, outbreak alerts are important to mobilise vector control and to prime or reorganise healthcare delivery services in preparation for a surge in suspected cases. Vector control tools can be effective in principle, implementation remains an issue and effective dengue routine prevention is rarely achieved, in high-density urban communities (Horstick et al 2010; Pilger et al 2010). Emergency vector control operations in response to dengue outbreaks
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