Spatiotemporal Patterns of Leprosy in Southern Thailand: Identifying High-burden Districts Over 25 Years

Thailand has achieved leprosy elimination at the national level. However, sporadic cases still occur in rural areas, especially in the southern provinces. This study investigates the spatiotemporal distribution and burden of leprosy in Health Region 12 over 25 years, highlighting high-burden districts.

A retrospective, population-based cross-sectional study was conducted using leprosy surveillance data from 1999 to 2023 across 77 districts in seven southern provinces. A two-step analytical approach was used to analyse leprosy case counts classified by gender-age group, year, and district. The two-step analytic approach involves separately fitting a logistic model for leprosy occurrence and a log-linear regression model for leprosy incidence without zeros, and the results were combined.

A total of 1233 new leprosy cases were reported, with a median age of 41 years and a predominance of multibacillary cases (73.2 %). Males accounted for 64 % of cases. Leprosy incidence increased with age, peaking among individuals aged 70 years and over. Leprosy occurrence and incidence rates are on a decreasing trend. Four districts in Pattani and seven districts in Narathiwat were identified as high-burden areas, characterised by above-average occurrence and incidence rates.

Although Thailand has achieved leprosy eradication on the national level, some districts in southernmost provinces have not to achieve leprosy elimination. These findings highlight the need for intensified surveillance and targeted interventions at the subnational level.