Are imported cases the reason for increase in incidence of dengue in Anuradhapura District during the recent years?

Abstract

Dengue has now become endemic in almost all districts of Sri Lanka. An increase in the percentage contribution from North Central Province (NCP) to dengue incidence in the country has been noted since the 2015 dengue outbreak. During the year 2017, 338 patients per 100,000 population were reported to have clinically suspected dengue according to the epidemiology unit records. The daily records available at the dengue control unit of regional director of health services office, Anuradhapura, and the freely available data at the epidemiology unit, which comprised of weekly cases of dengue, were extracted and analysed against the meteorological parameters and the vector density data. According to our observations, a statistically significant association between daily rainfall and daily temperature and clinically diagnosed dengue cases does not exist in Anuradhapura. The monthly vector indices did not show any correlation with the monthly incidence of dengue in the medical officer of health area with the highest overall incidence of dengue. The proportion of paediatric patients were also very low in the Anuradhapura district (9%) compared to other districts. Based on these observations, the authors suggest that imported cases of dengue to this district is a major cause of increased incidence of dengue, rather than indigenous transmission in the area.