Abstract
BACKGROUND: Pertussis remains a significant public health concern in Thailand’s southernmost provinces, where low vaccination coverage has contributed to recurring outbreaks. This study aimed to identify high-risk sub-districts and analyze pertussis trends from 2015 to July 2024, accounting for gender-age group variations. METHODS: We analyzed pertussis surveillance data from four provinces (Songkhla, Pattani, Yala, and Narathiwat) comprising 377 sub-districts. Cases were categorized into five age groups (< 1, 1–4, 5–9, 10–19, and 20 + years) combined with gender to create 10 gender-age groups. Data structure included 30,160 records across 8 years. Using a two-step modeling approach, we applied logistic regression for occurrence analysis and log-linear regression for incidence rates without zero. The results were combined to identify high-risk areas. RESULTS: A total of 1,677 pertussis cases were recorded, corresponding to an overall occurrence rate of 5.04%, with median and incidence rate of 6.64 and 13.53 per 1,000 population, respectively. No cases were reported during 2021–2022, but significant increases occurred in 2023–2024, with occurrence rates reaching 24.96%. Infants under 1 year and children aged 1–4 years showed the highest risk regardless of gender. Forty-five sub-districts were identified as high-risk areas, predominantly concentrated in Pattani (25 sub-districts) and Yala (13 sub-districts). CONCLUSIONS: Young children aged less than 1 and 1–4 years constitute the highest-risk group for pertussis in Thailand’s southernmost provinces. The concentration of cases in rural, densely populated areas of Pattani and Yala with Aiyoewaeng as the hotspot area highlights the urgent need for targeted vaccination strategies and improved vaccine coverage, particularly focusing on maternal vaccination and addressing religious and cultural barriers to immunization.