Sri Lanka: Dengue Outbreak - May 2023

As a result of the intensifying rainfall caused by the Southeast monsoon, Health departments have warned that the Dengue situation has the potential to become critical. According to NDCU, the ongoing inclement weather conditions will only further aggravate the breeding of mosquitos, hence worsening the spread of the outbreak. Notably, since the start of 2023, some 33,742 dengue cases have been recorded across the island, with the highest numbers recorded in Colombo, Gampaha, and Kalutara districts in Western Province, and Batticaloa, Trincomalee in Eastern Province, Kandy - Central province, Galle - Southwestern Province recorded high numbers of cases all around the country.

Based on the NDCU update of 18 May 2023, there are eight districts (Colombo, Gampaha, Trincomalee, Batticaloa, Kalutara, Kandy, Kegalle, and Galle) that have reported more dengue cases, and a total of 23,222 cases so far reported, according to the 19th-week update of NDCU. The NDCU and Regional Directorate of Health Services (RDHS) have identified those districts as high-risk zones, where dengue fever is rapidly increasing. The new cases in May alone have reached almost 6,000, raising concerns about the disease's rapid spread.

Overall, the above situation of an active dengue outbreak combined with prevailing weather conditions could quickly deteriorate to a situation similar to that of 2017, when the country faced a major outbreak in the same districts currently affected, with 68,053 cases and 205 deaths (of which 25 per cent were children) reported during the period. Approximately 42.40 per cent of dengue cases were also reported from the Western province in 2017. (IFRC, 3 Jun 2023)

As of 25 August, a total of 61,361 cases of dengue have been reported in Sri Lanka in 2023. This compares with 53,181 cases reported until the end of week 34 in 2022 (26 August). In 2023, a total of 1,219 cases of dengue were reported in Sri Lanka in week 34 (19 to 25 August 2023), a 4.5% increase compared to week 33 (12 to 18 August, n=1,166) and 96.1% of the mean number of cases reported during week 34 from 2017 to 2022 (n=1,268). (WHO, 20 Sep 2023)

As of 8 September, a total of 62,783 cases of dengue have been reported in Sri Lanka in 2023, 1.1 times higher than the 55,462 cases reported until the end of week 36 in 2022 (11 September). In 2023, a total of 838 cases of dengue were reported in Sri Lanka in week 36 (2 to 8 September 2023), a 15.0% increase compared to week 35 (26 August to 1 September August, n=1,166). (WHO, 4 Oct 2023)

As of 22 September, a total of 64,109 cases of dengue have been reported in Sri Lanka in 2023, 1.1 times higher than the 57,454 cases reported until the end of week 38 in 2022 (25 September). A total of 624 cases of dengue were reported in Sri Lanka in week 38 (16 to 22 September 2023), a 11.1% decrease compared to week 37 (9 September to 15 September, n=702). (WHO, 18 Oct 2023)