A seroprevalence study of chikungunya was conducted in Colombo, Sri Lanka, from September to November 2024, prior to a major outbreak in December 2024. Of 1196 participants, 410 (34.3%) were seropositive. Seroprevalence was higher in urban areas (39.6%) than in semi-urban areas (22.9%) and increased with age in urban areas.
Living in an urban area was the main independent risk factor. Use of mosquito nets was associated with a lower risk. Few children under 16 years of age showed prior infection (0.55%), indicating minimal transmission in the previous 16 years. Urban seroprevalence was associated with diabetes, obesity, overweight, and hypertension.
The study concludes that a large population is susceptible to chikungunya.
