In 2017, a dengue epidemic of unexpected magnitude occurred in Sri Lanka. A total of 186,101 suspected cases and 440 dengue-related deaths occurred. We conducted a comprehensive analysis of this epidemic by comparing national surveillance data for 2017 with data from the preceding 5 years. In all Sri Lanka districts, dengue incidence in 2017 increased significantly over incidence during the previous 5 years. Older schoolchildren and young adults were more clinically symptomatic than those at extremes of age. Limited virologic surveillance showed the dominant circulating variant was dengue virus type 2 cosmopolitan genotype in the most affected district. One quarter of total annual cases were reported 5 weeks after the southwest monsoon started. Changes in vector abundance were not predictive of the increased incidence. Direct government expenditures on dengue control activities in 2017 were US $12.7 million. The lessons learned from this outbreak are useful for other tropical nations facing increasing dengue incidence.

2017年，斯里兰卡发生了意外规模的登革热流行病。总共发生186,101例疑似病例，并发生了440例与登革热有关的死亡。我们通过比较2017年的国家监测数据和前5年的数据对这一流行病进行了全面分析。在所有斯里兰卡地区，2017年的登革热发病率比前五年的发病率显着增加。与年龄极端的学生相比，年龄较大的小学生和年轻人在临床上更具症状。有限的病毒学监测显示，在受影响最严重的地区，主要的循环变异是登革热病毒2型世界性基因型。在西南季风爆发后的第5周，报告了全年病例的四分之一。载体丰度的变化不能预测发病率的增加。2017年，政府在登革热控制活动上的直接支出为1,270万美元。从这次暴发中吸取的教训对于其他面临登革热发病率不断上升的热带国家很有用。