Scrub Typhus in Sri Lanka: Assessing the Burden and Spatial Distribution Using National Surveillance Data, 2020–2024

Background and aim: Scrub typhus is an acute zoonotic infection caused by Orientis tsutsugamushi and transmitted through the bite of infected chigger mites. It is increasingly recognized as a major cause of acute undifferentiated febrile illness across the Asia–Pacific region. In Sri Lanka, scrub typhus has re-emerged as an important public health concern, yet comprehensive national-level analyses describing its epidemiological trends and distribution remain limited. This study aims to assess the burden, geographical distribution, and temporal trends of scrub typhus in Sri Lanka over a five-year period from 2020 to 2024. Method: A retrospective descriptive study was conducted using secondary surveillance data obtained from the Weekly Return of Communicable Diseases (WRCD) published by the Epidemiology Unit of the Ministry of Health, Sri Lanka. Reported scrub typhus cases from January 2020 to December 2024 were extracted and analyzed. Data were summarized using frequencies and percentages to describe annual trends and district-wise distribution of cases. Results: A total of 5,947 scrub typhus cases were reported nationally during the five-year study period. The annual trend demonstrated fluctuations, with a temporary decline in reported cases in 2021, likely influenced by disruptions to healthcare services and disease surveillance during the COVID-19 pandemic. However, case numbers increased again in the subsequent years, indicating a persistent endemic presence. The geographical distribution of cases showed marked heterogeneity, with the northern district of Jaffna accounting for more than 53% of the total national burden. Other districts reported relatively lower case numbers, suggesting possible variations in ecological exposure, diagnostic capacity, and clinical awareness. Conclusion: Scrub typhus remains an important public health concern in Sri Lanka with a sustained burden and notable geographical clustering. Strengthening laboratory diagnostic capacity, enhancing clinician awareness, improving surveillance systems, and implementing targeted preventive measures for high-risk occupational groups are essential to improve early detection and reduce the disease burden. Geographically stratified surveillance and focused interventions in high-risk districts are recommended to strengthen control efforts.