Epidemiological changes in the incidence of human leptospirosis in Thailand: Findings from the National Disease Surveillance System from 2013 to 2022

Objectives

To describe the epidemiological changes in leptospirosis incidence from 2013 to 2022, and to further quantify factors associated with leptospirosis mortality in Thailand.

Methods

We analyzed the epidemiological trends of leptospirosis incidence using data from the National Disease Surveillance System from January 2013 to December 2022 and estimated potential factors associated with leptospirosis mortality using a multiple logistic regression model.

Results

A total of 25,006 cases were reported during the study period, with an average incidence rate of 3.8 cases per 100,000 population. The incidence rate gradually decreased from 2013 to 2021, followed by a sharp increase in 2022. The case fatality rate increased steadily from 2013 to 2015 and then began to decline after 2015. A higher incidence rate was observed in men than in women, in individuals aged ≥15 years than in children <15 years, in residents of rural areas than urban areas, in people living in the southwestern region than in those living in other regions, and in individuals engaged in agriculture. We also observed that age groups, regions of residence, healthcare facilities and services, and duration from symptom onset to treatment initiation were significantly associated with a mortality risk from leptospirosis.

Conclusion

A decreasing trend in leptospirosis incidence was observed from 2013 to 2021, followed by a recent increase in 2022, indicating that it is crucial to enhance the current surveillance system for implementing targeted interventions and to develop appropriate guidelines for reducing leptospirosis incidence and mortality by controlling the associated prognostic factors.