Reconstruction of 60 years of chikungunya epidemiology in the Philippines demonstrates episodic and focal transmission

Type Journal Article - The Journal of infectious diseases
Title Reconstruction of 60 years of chikungunya epidemiology in the Philippines demonstrates episodic and focal transmission
Author(s)
Volume 213
Issue 4
Publication (Day/Month/Year) 2016
Page numbers 604-610
URL https://academic.oup.com/jid/article/213/4/604/2459450
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.

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