Epidemiology of Chikungunya Virus Infection in the Philippines

Background: Chikungunya virus (CHIKV) has circulated in the Philippines for more than six decades. We systematically reviewed the epidemiology of CHIKV in the Philippines, integrating evidence on transmission, seroprevalence, diagnostics and molecular lineages. Methods: We searched PubMed and Embase to March 2026 for original studies reporting incidence, prevalence, seroprevalence, outbreak characteristics, or surveillance findings in human populations in the Philippines. The gray literature from the Department of Health (DOH) Epidemiology Bureau's national chikungunya surveillance (2018-March 2026) was included separately. Findings were synthesized narratively because of substantial heterogeneity. Results: Sixteen studies and one national surveillance dataset were included. National surveillance recorded 12,662 cases from 2018 to early 2026, including 722 laboratory-confirmed cases and three fatalities. The Asian genotype predominated during the 2011-2013 epidemic, while Indian Ocean lineage (IOL) viruses were detected in southern Mindanao. Conclusions: Transmission of CHIKV in the Philippines is mostly sporadic with periods of low-level transmission. Because the clinical features overlap with dengue, acute febrile illness surveillance should test for both viruses.