Severe Dengue Epidemic, Sri Lanka, 2017

Area of Science:

• Epidemiology
• Infectious Diseases
• Public Health

Background:

• Sri Lanka faced an unprecedented dengue epidemic in 2017, reporting 186,101 suspected cases and 440 deaths.
• Dengue incidence has been increasing globally, posing a significant public health challenge in tropical nations.

Purpose of the Study:

• To conduct a comprehensive analysis of the 2017 dengue epidemic in Sri Lanka.
• To compare the 2017 epidemic data with national surveillance data from the preceding five years.

Main Methods:

• Analysis of national surveillance data for dengue cases and deaths in 2017.
• Comparison of 2017 incidence rates with the average rates from 2012-2016 across all Sri Lankan districts.
• Limited virologic surveillance to identify dominant dengue virus serotypes and genotypes.

Main Results:

• Dengue incidence significantly increased in all districts in 2017 compared to the previous five years.
• Older schoolchildren and young adults presented with more severe clinical symptoms.
• Dengue virus type 2 (cosmopolitan genotype) was the dominant circulating variant in the most affected district.
• A quarter of annual cases occurred within five weeks after the southwest monsoon onset.
• Vector abundance changes did not predict the increased incidence.
• Government expenditure on dengue control was US $12.7 million in 2017.

Conclusions:

• The 2017 dengue epidemic in Sri Lanka was characterized by a widespread and significant increase in incidence.
• Demographic patterns of symptomatic cases and specific viral genotypes were identified.
• Understanding the dynamics of this outbreak offers valuable lessons for dengue prevention and control in other tropical countries.