{Reference Type}: Historical Article
{Title}: Reconstruction of 60 Years of Chikungunya Epidemiology in the Philippines Demonstrates Episodic and Focal Transmission.
{Author}: Salje H;Cauchemez S;Alera MT;Rodriguez-Barraquer I;Thaisomboonsuk B;Srikiatkhachorn A;Lago CB;Villa D;Klungthong C;Tac-An IA;Fernandez S;Velasco JM;Roque VG;Nisalak A;Macareo LR;Levy JW;Cummings D;Yoon IK;
{Journal}: J Infect Dis
{Volume}: 213
{Issue}: 4
{Year}: Feb 2016 15
{Factor}: 7.759
{DOI}: 10.1093/infdis/jiv470
{Abstract}: 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.