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Srikiatkhachorn A, Alera MT, Lago CB, Tac-An IA, Villa D, Fernandez S, Thaisomboonsuk B, Klungthong C, Levy JW, Velasco JM, Roque VG, Nisalak A, Macareo LR, Yoon IK. Resolution of a Chikungunya Outbreak in a Prospective Cohort, Cebu, Philippines, 2012-2014. Emerg Infect Dis 2018; 22:1852-4. [PMID: 27649081 PMCID: PMC5038399 DOI: 10.3201/eid2210.160729] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Alera MT, Srikiatkhachorn A, Velasco JM, Tac-An IA, Lago CB, Clapham HE, Fernandez S, Levy JW, Thaisomboonsuk B, Klungthong C, Macareo LR, Nisalak A, Hermann L, Villa D, Yoon IK. Incidence of Dengue Virus Infection in Adults and Children in a Prospective Longitudinal Cohort in the Philippines. PLoS Negl Trop Dis 2016; 10:e0004337. [PMID: 26845762 PMCID: PMC4742283 DOI: 10.1371/journal.pntd.0004337] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 12/07/2015] [Indexed: 11/19/2022] Open
Abstract
Background The mean age of dengue has been increasing in some but not all countries. We sought to determine the incidence of dengue virus (DENV) infection in adults and children in a prospective cohort study in the Philippines where dengue is hyperendemic. Methodology/Principal Findings A prospective cohort of subjects ≥6 months old in Cebu City, Philippines, underwent active community-based surveillance for acute febrile illnesses by weekly contact. Fever history within the prior seven days was evaluated with an acute illness visit followed by 2, 5, and 8-day, and 3-week convalescent visits. Blood was collected at the acute and 3-week visits. Scheduled visits took place at enrolment and 12 months that included blood collections. Acute samples were tested by DENV PCR and acute/convalescent samples by DENV IgM/IgG ELISA to identify symptomatic infections. Enrolment and 12-month samples were tested by DENV hemagglutination inhibition (HAI) assay to identify subclinical infections. Of 1,008 enrolled subjects, 854 completed all study activities at 12 months per-protocol undergoing 868 person-years of surveillance. The incidence of symptomatic and subclinical infections was 1.62 and 7.03 per 100 person-years, respectively. However, in subjects >15 years old, only one symptomatic infection occurred whereas 27 subclinical infections were identified. DENV HAI seroprevalence increased sharply with age with baseline multitypic HAIs associated with fewer symptomatic infections. Using a catalytic model, the historical infection rate among dengue naïve individuals was estimated to be high at 11–22%/year. Conclusions/Significance In this hyperendemic area with high seroprevalence of multitypic DENV HAIs in adults, symptomatic dengue rarely occurred in individuals older than 15 years. Our findings demonstrate that dengue is primarily a pediatric disease in areas with high force of infection. However, the average age of dengue could increase if force of infection decreases over time, as is occurring in some hyperendemic countries such as Thailand. The average age of dengue has been increasing in some but not all dengue endemic countries. To investigate the age pattern of dengue in people of all ages ≥6 months old, a prospective community-based cohort study was undertaken in Cebu City, Philippines where dengue virus has been circulating for many decades. Active surveillance for acute fevers was performed, and acute/convalescent blood samples were tested for evidence of symptomatic dengue. Blood was also collected at enrolment and one year later, and tested serologically to identify subclinical infections. Overall, 1.62 symptomatic and 7.03 subclinical infections per 100 person-years of surveillance were detected. Among people older than 15 years, only one symptomatic dengue case occurred while 27 subclinical infections were identified. By analyzing age-specific dengue serology data, the historical infection rate among people with no prior dengue virus infection was found to be high at around 11–22% per year. Our results show that dengue is primarily a childhood disease in endemic settings where the historical infection rate has been high. However, the average age of dengue could increase if the infection rate decreases over time as is happening in some endemic countries like Thailand.
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Affiliation(s)
- Maria Theresa Alera
- Philippines-AFRIMS Virology Research Unit, CAP Building, Cebu City, Philippines
| | - Anon Srikiatkhachorn
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - John Mark Velasco
- Philippines-AFRIMS Virology Research Unit, CAP Building, Cebu City, Philippines
| | | | - Catherine B Lago
- Philippines-AFRIMS Virology Research Unit, CAP Building, Cebu City, Philippines
| | - Hannah E Clapham
- Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Stefan Fernandez
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Jens W Levy
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Butsaya Thaisomboonsuk
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Chonticha Klungthong
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Louis R Macareo
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Ananda Nisalak
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Laura Hermann
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Daisy Villa
- Cebu City Health Department, Cebu City, Philippines
| | - In-Kyu Yoon
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
- Dengue Vaccine Initiative, International Vaccine Institute, Seoul, Korea
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Alera MT, Hermann L, Tac-An IA, Klungthong C, Rutvisuttinunt W, Manasatienkij W, Villa D, Thaisomboonsuk B, Velasco JM, Chinnawirotpisan P, Lago CB, Roque VG, Macareo LR, Srikiatkhachorn A, Fernandez S, Yoon IK. Zika virus infection, Philippines, 2012. Emerg Infect Dis 2015; 21:722-4. [PMID: 25811410 PMCID: PMC4378478 DOI: 10.3201/eid2104.141707] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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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. Reconstruction of 60 Years of Chikungunya Epidemiology in the Philippines Demonstrates Episodic and Focal Transmission. J Infect Dis 2015; 213:604-10. [PMID: 26410592 PMCID: PMC4721913 DOI: 10.1093/infdis/jiv470] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/16/2015] [Indexed: 11/15/2022] Open
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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Affiliation(s)
- Henrik Salje
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Mathematical Modeling Unit, Institut Pasteur, Paris, France
| | | | | | | | - Butsaya Thaisomboonsuk
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Anon Srikiatkhachorn
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester
| | - Catherine B Lago
- Virology Research Unit, Armed Forces Research Institute of Medical Sciences
| | | | - Chonticha Klungthong
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | | | - Stefan Fernandez
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - John Mark Velasco
- Virology Research Unit, Armed Forces Research Institute of Medical Sciences
| | - Vito G Roque
- Department of Health, National Epidemiology Center, Manila, Philippines
| | - Ananda Nisalak
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Louis R Macareo
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Jens W Levy
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Derek Cummings
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Department of Biology, University of Florida, Gainesville
| | - In-Kyu Yoon
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand International Vaccine Institute, Seoul, Republic of Korea
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Yoon IK, Alera MT, Lago CB, Tac-An IA, Villa D, Fernandez S, Thaisomboonsuk B, Klungthong C, Levy JW, Velasco JM, Roque VG, Salje H, Macareo LR, Hermann LL, Nisalak A, Srikiatkhachorn A. High rate of subclinical chikungunya virus infection and association of neutralizing antibody with protection in a prospective cohort in the Philippines. PLoS Negl Trop Dis 2015; 9:e0003764. [PMID: 25951202 PMCID: PMC4423927 DOI: 10.1371/journal.pntd.0003764] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/15/2015] [Indexed: 01/04/2023] Open
Abstract
Background Chikungunya virus (CHIKV) is a globally re-emerging arbovirus for which previous studies have indicated the majority of infections result in symptomatic febrile illness. We sought to characterize the proportion of subclinical and symptomatic CHIKV infections in a prospective cohort study in a country with known CHIKV circulation. Methods/Findings A prospective longitudinal cohort of subjects ≥6 months old underwent community-based active surveillance for acute febrile illness in Cebu City, Philippines from 2012-13. Subjects with fever history were clinically evaluated at acute, 2, 5, and 8 day visits, and at a 3-week convalescent visit. Blood was collected at the acute and 3-week convalescent visits. Symptomatic CHIKV infections were identified by positive CHIKV PCR in acute blood samples and/or CHIKV IgM/IgG ELISA seroconversion in paired acute/convalescent samples. Enrollment and 12-month blood samples underwent plaque reduction neutralization test (PRNT) using CHIKV attenuated strain 181/clone25. Subclinical CHIKV infections were identified by ≥8-fold rise from a baseline enrollment PRNT titer <10 without symptomatic infection detected during the intervening surveillance period. Selected CHIKV PCR-positive samples underwent viral isolation and envelope protein-1 gene sequencing. Of 853 subjects who completed all study procedures at 12 months, 19 symptomatic infections (2.19 per 100 person-years) and 87 subclinical infections (10.03 per 100 person-years) occurred. The ratio of subclinical-to-symptomatic infections was 4.6:1 varying with age from 2:1 in 6 month-5 year olds to 12:1 in those >50 years old. Baseline CHIKV PRNT titer ≥10 was associated with 100% (95%CI: 46.1, 100.0) protection from symptomatic CHIKV infection. Phylogenetic analysis demonstrated Asian genotype closely related to strains from Asia and the Caribbean. Conclusions Subclinical infections accounted for a majority of total CHIKV infections. A positive baseline CHIKV PRNT titer was associated with protection from symptomatic CHIKV infection. These findings have implications for assessing disease burden, understanding virus transmission, and supporting vaccine development. Chikungunya virus (CHIKV) is a re-emerging mosquito-borne pathogen for which the majority of infections have been considered to result in febrile illness. We sought to characterize the proportion of subclinical and symptomatic CHIKV infections in a prospective cohort of subjects ≥6 months old who underwent active surveillance for acute febrile illness from 2012–13 in Cebu City, Philippines. Symptomatic CHIKV infections were detected by PCR and/or ELISA in acute/convalescent blood samples. Subclinical infections were identified by neutralizing antibody seroconversion between enrollment and 12-month visits without symptomatic infection. Among 853 subjects who completed all study activities at 12 months, 19 symptomatic and 87 subclinical infections occurred (2.19 and 10.03 per 100 person-years, respectively). A positive baseline CHIKV PRNT titer was associated with 100% (95%CI: 46.1, 100.0) protection from symptomatic infection. Phylogenetic analysis showed Asian genotype closely related to strains from the recent Caribbean epidemic. These findings can help to assess disease burden, understand virus transmission, and support vaccine development.
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Affiliation(s)
- In-Kyu Yoon
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
- * E-mail:
| | | | | | | | - Daisy Villa
- Cebu City Health Department, Cebu City, Philippines
| | - Stefan Fernandez
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Butsaya Thaisomboonsuk
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Chonticha Klungthong
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Jens W. Levy
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | | | - Vito G. Roque
- National Epidemiology Center, Department of Health, Manila, Philippines
| | - Henrik Salje
- Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, Maryland, United States of America
| | - Louis R. Macareo
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Laura L. Hermann
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ananda Nisalak
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Anon Srikiatkhachorn
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
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Natividad FF, Buerano CC, Lago CB, Mapua CA, de Guzman BB, Seraspe EB, Samentar LP, Endo T. Prevalence rates of Giardia and Cryptosporidium among diarrheic patients in the Philippines. Southeast Asian J Trop Med Public Health 2008; 39:991-999. [PMID: 19062686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The prevalence of Giardia and Cryptosporidium among 3,456 diarrheic patients corrected from May 2004 to May 2005 in the Philippines was determined. Of 133 (3.8%) positive samples, 69 (2.0%) were positive for Giardia and 67 (1.9%) for Cryptosporidium. Three samples had co-infection with Giardia and Cryptosporidium. Luzon had the highest positive samples (5.0%) followed by Mindanao (4.9%), then Visayas (2.2%). Giardia was most prevalent in Mindanao (3.6%) while Cryptosporidium was most prevalent in Luzon (3.1%). The prevalence of Giardia (2.0%) among pediatric patients (0-18 years) did not significantly differ from that (1.9%) among adults (> 18 years old). However, for Cryptosporidium, the prevalence (2.9%) among pediatric patients was significantly higher compared to that (0.2%) among adult patients. In the pediatric population, the highest percentage of patients with Giardia was the 5-9 year old age group, while that of Cryptosporidium was in the 0-4 year old group. The prevalence of Giardia, but not Cryptosporidium, was significantly higher in male than female adults. Seasonality had a distinct peak in September with Cryptosporidium more prevalent in the rainy (2.6%) than dry season (0.9%).
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Affiliation(s)
- Filipinas F Natividad
- Research and Biotechnology Division, St Luke's Medical Center, 279 E Rodriguez Sr Avenue, Quezon City 1102, Philippines.
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