Epidemiology and costs of dengue in Thailand: A systematic literature review

Background: Dengue is the fastest-spreading vector-borne viral disease worldwide. In Thailand, dengue is endemic and is associated with a high socioeconomic burden. A systematic literature review was conducted to assess and describe the epidemiological and economic burden of dengue in Thailand. Methods: Epidemiological and economic studies published in English and Thai between 2011–2019 and 2009–2019, respectively, were searched in MEDLINE, Embase, and Evidence-Based Medicines reviews databases. Reports published by the National Ministry of Public Health (MoPH) and other grey literature sources were also reviewed. Identified studies were screened according to predefined inclusion and exclusion criteria. Extracted data were descriptively summarised and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: A total of 155 publications were included in the review (39 journal articles and 116 grey literature). Overall, dengue incidence varied yearly, with the highest rates per 100,000 population in 2013 (dengue fever (DF) 136.6, dengue haemorrhagic fever (DHF) 100.9, dengue shock syndrome (DSS) 3.58) and 2015 (DF 133.1, DHF 87.4, DSS 2.14). Peak incidence coincided with the monsoon season, and annual mortality was highest for DSS, particularly in the age group 15–24-year-olds. The highest dengue incidence rates were reported in children (10–14-year-olds) and young adults (15-24-year-olds), irrespective of dengue case definition. Economic and societal burdens are extensive, with the average cost per case ranging from USD 41 to USD 261, total cost per year estimated at USD 440.3 million, and an average of 7.6 workdays lost for DHF and 6.6 days for DF. Conclusions: The epidemiological, economic, and societal burden of dengue in Thailand is high and underreported due to gaps in national surveillance data. The use of expansion factors (EFs) is recommended to understand the true incidence of dengue and cost-benefit of control measures. Furthermore, as dengue is often self-managed and underreported, lost school and workdays result in substantial underestimation of the true economic and societal burden of dengue. The implementation of integrated strategies, including vaccination, is critical to reduce the disease burden and may help alleviate health disparities and equity challenges posed by dengue. Author summary: Dengue is a vector-borne viral disease affecting over 100 million people globally. In Thailand, dengue is endemic, but the true estimation of the disease burden is underreported. A systematic literature search for epidemiological (2011–2019) and economic (2009–2019) studies was conducted to analyse the disease incidence, seroprevalence, serotype distribution, mortality, expansion factor, and direct and indirect costs at a country and regional level. Peak dengue incidence was highest in 2013 and 2015 and overlapped with the annual monsoon season. Children and young adults were the most affected population, with the highest case fatality rates found in young adults aged 15–24 years with dengue shock syndrome (DSS). Limited evidence indicates a high economic and societal impact of dengue. These estimates place dengue as a significant public health concern in Thailand and emphasise the need for introducing an integrated disease management programme including vaccination strategies.