title: Reconstruction of 60 Years of Chikungunya Epidemiology in the Philippines Demonstrates Episodic and Focal Transmission.
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.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Mathematical Modeling Unit, Institut Pasteur, Paris, France.
authors.forename: Henrik
authors.initials: H
authors.lastname: Salje
authors.affiliation: Mathematical Modeling Unit, Institut Pasteur, Paris, France.
authors.forename: Simon
authors.initials: S
authors.lastname: Cauchemez
authors.affiliation: Virology Research Unit, Armed Forces Research Institute of Medical Sciences.
authors.forename: Maria Theresa
authors.initials: MT
authors.lastname: Alera
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Isabel
authors.initials: I
authors.lastname: Rodriguez-Barraquer
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Butsaya
authors.initials: B
authors.lastname: Thaisomboonsuk
authors.affiliation: Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester.
authors.forename: Anon
authors.initials: A
authors.lastname: Srikiatkhachorn
authors.affiliation: Virology Research Unit, Armed Forces Research Institute of Medical Sciences.
authors.forename: Catherine B
authors.initials: CB
authors.lastname: Lago
authors.affiliation: Cebu City Health Department, Cebu City.
authors.forename: Daisy
authors.initials: D
authors.lastname: Villa
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Chonticha
authors.initials: C
authors.lastname: Klungthong
authors.affiliation: Cebu City Health Department, Cebu City.
authors.forename: Ilya A
authors.initials: IA
authors.lastname: Tac-An
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Stefan
authors.initials: S
authors.lastname: Fernandez
authors.affiliation: Virology Research Unit, Armed Forces Research Institute of Medical Sciences.
authors.forename: John Mark
authors.initials: JM
authors.lastname: Velasco
authors.affiliation: Department of Health, National Epidemiology Center, Manila, Philippines.
authors.forename: Vito G
authors.initials: VG
authors.lastname: Roque
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Ananda
authors.initials: A
authors.lastname: Nisalak
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Louis R
authors.initials: LR
authors.lastname: Macareo
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Jens W
authors.initials: JW
authors.lastname: Levy
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Department of Biology, University of Florida, Gainesville.
authors.forename: Derek
authors.initials: D
authors.lastname: Cummings
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: Yoon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D065632:Chikungunya Fever / Q000453:epidemiology* / Q000266:history / Q000635:transmission*; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D018562:Disease Transmission, Infectious; D005260:Female; D049673:History, 20th Century; D049674:History, 21st Century; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010679:Philippines / Q000453:epidemiology; D055815:Young Adult
keywords: Philippines; chikungunya; epidemiology; modeling; serological study