Climate variability is associated with chikungunya outbreaks across the Indian Ocean Region

In the Indian Ocean Region (IOR), chikungunya virus (CHIKV) outbreaks have surged, driven by climate factors influencing vector ecology and transmission. We analyzed GeoSentinel traveler surveillance data from 2010 to 2024 alongside multiple climate indices representing dominant modes of regional variability, including the Mascarene Subtropical High (MSH), Indian Summer Monsoon, and El Niño Southern Oscillation. Here we identified region-specific associations: in South-Central Asia, chikungunya activity correlated strongly with intensified MSH area during El Niño; in sub-Saharan Africa, links were weaker and influenced by monsoon onset and cross-equatorial flow; in Southeast Asia, outbreaks followed moderate-to-large eastward MSH expansions with lagged effects. These findings suggest that large-scale climate variability modulates chikungunya transmission dynamics across the IOR. Incorporating such climate indicators into early warning systems may enhance outbreak forecasting and guide targeted public health interventions to mitigate chikungunya spread.