Epidemiological characteristics and risk factors of a Chikungunya outbreak in Bantul, Indonesia (April-May 2024): a matched case-control study

Abstract

Purpose: The study aims to confirm the outbreak and identify associated risk factors of Chikungunya-like illnesses in the working area of Puskesmas Imogiri I, Bantul. Methods: A matched case-control design (1:1) using neighborhood control was conducted. Cases (n=86) were individuals with fever and arthralgia residing in Garjoyo and Karangtalun, and controls (n=86) were healthy individuals from the same area. Purposive sampling was conducted among 731 individuals identified as the population at risk within a 100-meter radius of confirmed cases. Data were collected using standardized questionnaires and Rapid Diagnostic Test (RDT) and analyzed using conditional logistic regression. Results: Multivariate analysis identified low income (aOR 8.49; 95% CI: 2.76-26.13), travel history to endemic areas (aOR 7.29; 95% CI: 1.19-44.54), and male sex (aOR 2.67; 95% CI:1.19-5.97) as significant risk factors. Paradoxically, the absence of larvivorous fish (aOR 0.13; 95% CI: 0.06-0.32) and lack of mosquito-repellent plants (aOR 0.06; 95% CI: 0.01-0.57) were associated with lower odds of infection, indicating a profound temporal bias following post- outbreak interventions. Conclusion: This localized outbreak was primarily driven by mobility-related viral importation and socioeconomic vulnerabilities. The findings underscore the limitations of reactive interventions and highlight the need for proactive, community-based larval control integrated with travel-aware surveillance to prevent future arboviral transmission.