The burden of dengue and risk factors of transmission in nine districts in Sri Lanka

Background: It is crucial to understand the differences in dengue seroprevalence rates in different regions in Sri Lanka to understand the burden of infection to plan dengue vaccination programmes. Methods: age stratified seroprevalence rates were assessed in 5208 children, aged 10 to 19 years, in nine districts representing the nine provinces in Sri Lanka. A stratified multi-stage cluster was used to select 146 schools representing each district. Probability proportionate to the size (PPS) sampling technique based on the age distribution of general population and the urbanicity in each district was used to select the number of clusters to be enrolled for the study from each district. Findings: The overall dengue seroprevalence rates in children was 24.8%, with the highest rates reported from Trincomalee (54.3%) and the lowest rates from Badulla (14.2%), which is a high altitude estate area. There was a weak but positive correlation between the dengue antibody positivity rates and age in districts which had seroprevalence rates of >25%, while there was no increase in antibody titres with age in the other districts. While the seroprevalence rates was significantly higher in urban areas (35.8%) compared to rural (23.2%) and estate areas (9.4%), there was no association with seropositivity rates with population density (Spearmans r=- 0.01, p=0.98), in each district. Interpretation: The seroprevalence rates in many districts were <25% and the rates were very different to those reported from Colombo. Therefore, it would be important to take into account these differences when rolling out dengue vaccines in Sri Lanka. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement We are grateful to the World Health Organization and the UK Medical Research Council for support. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics approval was obtained by the Ethics review Committee, University of Sri Jayewardenepura and administrative clearance was obtained by the Ministry of Health, Sri Lanka. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.