%0 Historical Article
%T Reconstruction of 60 Years of Chikungunya Epidemiology in the Philippines Demonstrates Episodic and Focal Transmission.
%A Salje H
%A Cauchemez S
%A Alera MT
%A Rodriguez-Barraquer I
%A Thaisomboonsuk B
%A Srikiatkhachorn A
%A Lago CB
%A Villa D
%A Klungthong C
%A Tac-An IA
%A Fernandez S
%A Velasco JM
%A Roque VG
%A Nisalak A
%A Macareo LR
%A Levy JW
%A Cummings D
%A Yoon IK
%J J Infect Dis
%V 213
%N 4
%D Feb 2016 15
%M 26410592
%F 7.759
%R 10.1093/infdis/jiv470
%X Proper understanding of the long-term epidemiology of chikungunya has been hampered by poor surveillance. Outbreak years are unpredictable and cases often misdiagnosed. Here we analyzed age-specific data from 2 serological studies (from 1973 and 2012) in Cebu, Philippines, to reconstruct both the annual probability of infection and population-level immunity over a 60-year period (1952-2012). We also explored whether seroconversions during 2012-2013 were spatially clustered. Our models identified 4 discrete outbreaks separated by an average delay of 17 years. On average, 23% (95% confidence interval [CI], 16%-37%) of the susceptible population was infected per outbreak, with >50% of the entire population remaining susceptible at any point. Participants who seroconverted during 2012-2013 were clustered at distances of <230 m, suggesting focal transmission. Large-scale outbreaks of chikungunya did not result in sustained multiyear transmission. Nevertheless, we estimate that >350 000 infections were missed by surveillance systems. Serological studies could supplement surveillance to provide important insights on pathogen circulation.