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J Infect Dis. 2016 Feb 15;213(4):604-10. doi: 10.1093/infdis/jiv470. Epub 2015 Sep 25.

Reconstruction of 60 Years of Chikungunya Epidemiology in the Philippines Demonstrates Episodic and Focal Transmission.

Author information

1
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Mathematical Modeling Unit, Institut Pasteur, Paris, France.
2
Mathematical Modeling Unit, Institut Pasteur, Paris, France.
3
Virology Research Unit, Armed Forces Research Institute of Medical Sciences.
4
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
5
Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
6
Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester.
7
Cebu City Health Department, Cebu City.
8
Department of Health, National Epidemiology Center, Manila, Philippines.
9
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Department of Biology, University of Florida, Gainesville.
10
Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand International Vaccine Institute, Seoul, Republic of Korea.

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.

KEYWORDS:

Philippines; chikungunya; epidemiology; modeling; serological study

PMID:
26410592
PMCID:
PMC4721913
DOI:
10.1093/infdis/jiv470
[Indexed for MEDLINE]
Free PMC Article

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