Evolution of dengue in Sri Lanka—changes in the virus, vector, and climate

Abstract

Despite the presence of dengue in Sri Lanka since the early 1960s, dengue has become a major public health issue, with a high morbidity and mortality. Aedes aegypti and Aedes albopictus are the vectors responsible for the transmission of dengue viruses (DENV). The four DENV serotypes (1, 2, 3, and 4) have been co-circulating in Sri Lanka for more than 30 years. The new genotype of DENV-1 has replaced an old genotype, and new clades of DENV-3 genotype III have replaced older clades. The emergence of new clades of DENV-3 in the recent past coincided with an abrupt increase in the number of dengue fever (DF)/dengue hemorrhagic fever (DHF) cases, implicating this serotype in severe epidemics. Climatic factors play a pivotal role in the epidemiological pattern of DF/DHF in terms of the number of cases, severity of illness, shifts in affected age groups, and the expansion of spread from urban to rural areas. There is a regular incidence of DF/DHF throughout the year, with the highest incidence during the rainy months. To reduce the morbidity and mortality associated with DF/DHF, it is important to implement effective vector control programs in the country. The economic impact of DF/DHF results from the expenditure on DF/DHF critical care units in several hospitals and the cost of case management.

Effect of Climatic Factors and Population Density on the Distribution of Dengue in Sri Lanka: A GIS Based Evaluation for Prediction of Outbreaks

“…The country gets rain from two monsoons: the South West monsoon prevails from April to September and the North East monsoon prevails from December to February. In between there are inter-monsoons in March to April and a second inter-monsoon in October and November [4]. Levels of humidity range from 60–90% during different seasons.…”

Phylogeography and Molecular Epidemiology of an Epidemic Strain of Dengue Virus Type 1 in Sri Lanka

“…9,10 In 2009, the arrival of a new DENV-1 viral strain coincided with the largest DHF epidemic (346 deaths) since dengue was made a reportable disease in 1996. 11,12 Dengue disease has reached epidemic proportions in Sri Lanka every year since 2009, 13 and DENV-1 has remained the predominant disease-causing serotype (Sirisena 14 and A. D. De Silva, unpublished data). In 2012 in Sri Lanka, there were 44,456 reported cases of clinically diagnosed dengue disease, of which over 10,000 cases were in the capital city of Colombo.…”

Knowledge on fever and its associated factors among the parents of the children who were treated as cases of dengue fever or dengue hemorrhagic fever in a tertiary care setting of a lower middle income country

“…Sri Lanka has been mentioned as one of the countries in which epidemic dengue is a major reason of fever burden among children [6]. In Sri Lanka, clinical dengue-like-illness had been reported from the beginning of the 20th century and was first confirmed serologically in 1962 [7].…”