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Value of syndromic surveillance within the Armed Forces for early warning during a dengue fever outbreak in French Guiana in 2006
Jean-Baptiste Meynard, Hervé Chaudet, Gaetan Texier, Vanessa Ardillon, Fran?oise Ravachol, Xavier Deparis, Henry Jefferson, Philippe Dussart, Jacques Morvan, Jean-Paul Boutin
BMC Medical Informatics and Decision Making , 2008, DOI: 10.1186/1472-6947-8-29
Abstract: Military syndromic surveillance allows the surveillance of suspected dengue fever cases among the 3,000 armed forces personnel. Within the same population, clinical surveillance uses several definition criteria for dengue fever cases, depending on the epidemiological situation. Civilian laboratory surveillance allows the surveillance of biologically confirmed cases, within the 200,000 inhabitants.It was shown that syndromic surveillance detected the dengue fever outbreak several weeks before clinical surveillance, allowing quick and effective enhancement of vector control within the armed forces. Syndromic surveillance was also found to have detected the outbreak before civilian laboratory surveillance.Military syndromic surveillance allowed an early warning for this outbreak to be issued, enabling a quicker public health response by the armed forces. Civilian surveillance system has since introduced syndromic surveillance as part of its surveillance strategy. This should enable quicker public health responses in the future.One of the main objectives of health surveillance systems is to provide early warning of disease outbreaks, which allows for acceleration and optimization of a public health response. In the current context of international bioterrorism threats, early warning has become increasingly important, and many countries, including the Armed Forces based in French Guiana, have incorporated warning systems into their civilian and military surveillance systems [1,2].French Guiana is a French overseas department in South America where tropical diseases responsible for outbreaks exist, such as dengue fever. Dengue fever is a viral disease, caused by an arbovirus of the Flaviviridae family in the Flavivirus genus. There are four viral serotypes of this virus, designated DENV-1, DENV-2, DENV-3 and DENV-4. It is transmitted by a mosquito vector called Stegomyia aegypti (formerly Aedes aegypti). Dengue is the predominant arthropod borne viral disease affecting hu
Dengue and dengue hemorrhagic fever epidemics in Brazil: what research is needed based on trends, surveillance, and control experiences?
Teixeira, Maria da Glória;Costa, Maria da Concei??o Nascimento;Barreto, Maurício Lima;Mota, Eduardo;
Cadernos de Saúde Pública , 2005, DOI: 10.1590/S0102-311X2005000500002
Abstract: dengue epidemics account annually for several million cases and deaths worldwide. the high endemic level of dengue fever and its hemorrhagic form correlates to extensive domiciliary infestation by aedes aegypti and multiple viral serotype human infection. this study analyzed serial case reports registered in brazil since 1981, describing incidence evolutionary patterns and spatial distribution. epidemic waves followed the introduction of every serotype (den 1 to 3), and reduction in susceptible individuals possibly accounted for decreasing case frequency. an incremental expansion of affected areas and increasing occurrence of dengue fever and its hemorrhagic form with high case fatality were noted in recent years. in contrast, efforts based solely on chemical vector control have been insufficient. moreover, some evidence demonstrates that educational measures do not permanently modify population habits. thus, as long as a vaccine is not available, further dengue control depends on potential results from basic interdisciplinary research and intervention evaluation studies, integrating environmental changes, community participation and education, epidemiological and virological surveillance, and strategic technological innovations aimed to stop transmission.
Dengue and dengue hemorrhagic fever epidemics in Brazil: what research is needed based on trends, surveillance, and control experiences?  [cached]
Teixeira Maria da Glória,Costa Maria da Concei??o Nascimento,Barreto Maurício Lima,Mota Eduardo
Cadernos de Saúde Pública , 2005,
Abstract: Dengue epidemics account annually for several million cases and deaths worldwide. The high endemic level of dengue fever and its hemorrhagic form correlates to extensive domiciliary infestation by Aedes aegypti and multiple viral serotype human infection. This study analyzed serial case reports registered in Brazil since 1981, describing incidence evolutionary patterns and spatial distribution. Epidemic waves followed the introduction of every serotype (DEN 1 to 3), and reduction in susceptible individuals possibly accounted for decreasing case frequency. An incremental expansion of affected areas and increasing occurrence of dengue fever and its hemorrhagic form with high case fatality were noted in recent years. In contrast, efforts based solely on chemical vector control have been insufficient. Moreover, some evidence demonstrates that educational measures do not permanently modify population habits. Thus, as long as a vaccine is not available, further dengue control depends on potential results from basic interdisciplinary research and intervention evaluation studies, integrating environmental changes, community participation and education, epidemiological and virological surveillance, and strategic technological innovations aimed to stop transmission.
Airport sentinel surveillance and entry quarantine for dengue infections following a fever screening program in Taiwan  [cached]
Kuan Mei-Mei,Chang Feng-Yee
BMC Infectious Diseases , 2012, DOI: 10.1186/1471-2334-12-182
Abstract: Background Dengue has not reached an endemic status in Taiwan; nevertheless, we have implemented a fever screening program at airports for the early detection of febrile passengers with a dengue infection. This study is intended to assess the performance of the airport screening procedures for dengue infection. Methods We analyzed data from the national surveillance system of the Taiwan Centers for Disease Control. We included the imported dengue cases reported by sentinel airports and clinics as well as the domestic cases from 2007–2010. Results Approximately 44.9% (95%CI: 35.73-54.13%) of the confirmed imported dengue cases with an apparent symptom (febrile) in the viremic stage were detected via the airport fever screening program, with an estimated positive predictive value of 2.36% (95% CI: 0.96- 3.75%) and a negative predictive value > 99.99%. Fluctuations in the number of the symptomatic imported dengue cases identified in the airports (X) were associated with the total number of imported dengue cases (Y) based on a regression analysis of a biweekly surveillance (i.e., n = 104, R2X:Y = 0.61, P < 0.005). Additionally, the fluctuating patterns in the cumulative numbers of the imported dengue cases (X) with a 1–2 month lead time (t) was in parallel with that of the domestic dengue cases (Y) based on a consecutive 4-year surveillance (i.e., n = 48, R2X(t-1):Y = 0.22, R2X(t-2):Y = 0.31, P < 0.001) from 2007–2010. Conclusions A moderate sensitivity of detecting dengue at the airports examined in this study indicated some limitations of the fever screening program for the prevention of importation. The screening program could assist in the rapid triage for self-quarantine of some symptomatic dengue cases that were in the viremic stage at the borders and contribute to active sentinel surveillance; however, the blocking of viral transmission to susceptible populations (neighbors or family) from all of the viremic travelers, including those with or without symptoms, is critical to prevent dengue epidemics. Therefore, the reinforcement of mosquito bite prevention and household vector control in dengue-endemic or dengue-competent hotspots during an epidemic season is essential and highly recommended.
Dengue Incidence in Urban and Rural Cambodia: Results from Population-Based Active Fever Surveillance, 2006–2008  [PDF]
Sirenda Vong ,Virak Khieu,Olivier Glass,Sowath Ly,Veasna Duong,Rekol Huy,Chantha Ngan,Ole Wichmann,G. William Letson,Harold S. Margolis,Philippe Buchy
PLOS Neglected Tropical Diseases , 2010, DOI: 10.1371/journal.pntd.0000903
Abstract: Background Dengue vaccines are now in late-stage development, and evaluation and robust estimates of dengue disease burden are needed to facilitate further development and introduction. In Cambodia, the national dengue case-definition only allows reporting of children less than 16 years of age, and little is known about dengue burden in rural areas and among older persons. To estimate the true burden of dengue in the largest province of Cambodia, Kampong Cham, we conducted community-based active dengue fever surveillance among the 0-to-19–year age group in rural villages and urban areas during 2006–2008. Methods and Findings Active surveillance for febrile illness was conducted in 32 villages and 10 urban areas by mothers trained to use digital thermometers combined with weekly home visits to identify persons with fever. An investigation team visited families with febrile persons to obtain informed consent for participation in the follow-up study, which included collection of personal data and blood specimens. Dengue-related febrile illness was defined using molecular and serological testing of paired acute and convalescent blood samples. Over the three years of surveillance, 6,121 fever episodes were identified with 736 laboratory-confirmed dengue virus (DENV) infections for incidences of 13.4–57.8/1,000 person-seasons. Average incidence was highest among children less than 7 years of age (41.1/1,000 person-seasons) and lowest among the 16-to-19–year age group (11.3/1,000 person-seasons). The distribution of dengue was highly focal, with incidence rates in villages and urban areas ranging from 1.5–211.5/1,000 person-seasons (median 36.5). During a DENV-3 outbreak in 2007, rural areas were affected more than urban areas (incidence 71 vs. 17/1,000 person-seasons, p<0.001). Conclusion The large-scale active surveillance study for dengue fever in Cambodia found a higher disease incidence than reported to the national surveillance system, particularly in preschool children and that disease incidence was high in both rural and urban areas. It also confirmed the previously observed focal nature of dengue virus transmission.
Exploring the relationships between dengue fever knowledge and Aedes aegypti breeding in St Catherine Parish, Jamaica: a pilot of enhanced low-cost surveillance
Stoler J, Brodine SK, Bromfield S, Weeks JR, Scarlett HP
Research and Reports in Tropical Medicine , 2011, DOI: http://dx.doi.org/10.2147/RRTM.S20571
Abstract: ring the relationships between dengue fever knowledge and Aedes aegypti breeding in St Catherine Parish, Jamaica: a pilot of enhanced low-cost surveillance Original Research (3372) Total Article Views Authors: Stoler J, Brodine SK, Bromfield S, Weeks JR, Scarlett HP Published Date June 2011 Volume 2011:2 Pages 93 - 103 DOI: http://dx.doi.org/10.2147/RRTM.S20571 Justin Stoler1, Stephanie K Brodine2, Simeon Bromfield3, John R Weeks1, Henroy P Scarlett4 1Department of Geography, San Diego State University, San Diego, CA, USA; 2Graduate School of Public Health, San Diego State University, San Diego, CA, USA; 3Mosquito Control Section, St Catherine Health Department, Spanish Town, Jamaica; 4Department of Community Health and Psychiatry, University of the West Indies at Mona, Kingston, Jamaica Purpose: Dengue fever has re-emerged as an increasingly significant global health threat amid diminishing resources pledged for its control in developing nations. Efforts to limit breeding of the dengue vector Aedes aegypti are often hampered by lack of community awareness of the disease. Methods: Sixty-eight households in St Catherine Parish, Jamaica completed a pilot knowledge, attitude, and practice questionnaire as part of a routine container survey for presence of A. aegypti larvae. Results: Infestation levels were high according to traditional Stegomyia indices (Breteau index = 325); however, general knowledge of dengue symptoms, A. aegypti breeding sites, and preventive practices was low. After examining the links between demographic characteristics, dengue knowledge, and the number of breeding sites per house, higher educational achievement was associated with higher dengue knowledge, but also with more unprotected containers. Overall dengue knowledge was not associated with household container counts. Spatial statistics identified weak clustering of larvae-positive containers, and larvae were concentrated in three key container types. Conclusion: Residents may only understand the role of certain container types, and significant gaps in general knowledge of the disease may inhibit vector control. This pilot demonstrates the feasibility of conducting inexpensive, rapid assessment of community knowledge and breeding levels for local governments lacking the resources for a more methodologically robust vector assessment strategy.
Reconstructing historical changes in the force of infection of dengue fever in Singapore: implications for surveillance and control
Egger,Joseph R; Ooi,Eng Eong; Kelly,David W; Woolhouse,Mark E; Davies,Clive R; Coleman,Paul G;
Bulletin of the World Health Organization , 2008, DOI: 10.1590/S0042-96862008000300011
Abstract: objective: to reconstruct the historical changes in force of dengue infection in singapore, and to better understand the relationship between control of aedes mosquitoes and incidence of classic dengue fever. methods: seroprevalence data were abstracted from surveys performed in singapore from 1982 to 2002. these data were used to develop two mathematical models of age seroprevalence. in the first model, force of infection was allowed to vary independently each year, while in the second it was described by a polynomial function. model-predicted temporal trends were analysed using linear regression. time series techniques were employed to investigate periodicity in predicted forces of infection, dengue fever incidence and mosquito breeding. findings: force of infection estimates showed a significant downward trend from 1966, when vector control was instigated. force of infection estimates from both models reproduced significant increases in the percentage and average age of the population susceptible to dengue infections. importantly, the year-on-year model independently predicted a five to six year periodicity that was also displayed by clinical incidence but absent from the aedes household index. conclusion: we propose that the rise in disease incidence was due in part to a vector-control-driven reduction in herd immunity in older age groups that are more susceptible to developing clinical dengue.
Surveillance of Dengue Fever Virus: A Review of Epidemiological Models and Early Warning Systems  [PDF]
Vanessa Racloz ,Rebecca Ramsey,Shilu Tong,Wenbiao Hu
PLOS Neglected Tropical Diseases , 2012, DOI: 10.1371/journal.pntd.0001648
Abstract: Dengue fever affects over a 100 million people annually hence is one of the world's most important vector-borne diseases. The transmission area of this disease continues to expand due to many direct and indirect factors linked to urban sprawl, increased travel and global warming. Current preventative measures include mosquito control programs, yet due to the complex nature of the disease and the increased importation risk along with the lack of efficient prophylactic measures, successful disease control and elimination is not realistic in the foreseeable future. Epidemiological models attempt to predict future outbreaks using information on the risk factors of the disease. Through a systematic literature review, this paper aims at analyzing the different modeling methods and their outputs in terms of acting as an early warning system. We found that many previous studies have not sufficiently accounted for the spatio-temporal features of the disease in the modeling process. Yet with advances in technology, the ability to incorporate such information as well as the socio-environmental aspect allowed for its use as an early warning system, albeit limited geographically to a local scale.
El componente ambiental de la vigilancia integrada para el control y la prevención del dengue The environmental component of an integrated surveillance for the control and prevention of dengue fever  [cached]
Maricel García Melián,María de los ángeles Mariné Alonso,Cristina Díaz Pantoja,Miriam Concepción Rojas
Revista Cubana de Higiene y Epidemiología , 2007,
Abstract: Se presentan los resultados del dise o y ensayo del componente ambiental del sistema de vigilancia integrado para la prevención y el control del dengue en el área de salud “Efraín Mayor” del municipio Cotorro, Ciudad de La Habana, Cuba. El sistema se ensayó entre las fases 69 y 76 de la Campa a de Vigilancia y Lucha Antivectorial. Se emplearon siete indicadores, a nivel de manzana. Para la recolección de datos se modificó el modelo estadístico 91-06 utilizado por el operario “A” y se incorporó la observación de nuevos elementos ambientales en su trabajo de rutina. Las manzanas se clasificaron por los resultados de cada indicador y se elaboraron dos indicadores integrados que reflejaron las condiciones del ambiente intra y extradomiciliario, con el objetivo de facilitar el manejo ambiental. En el estudio de la asociación de los indicadores de resumen y el integrado del ambiente intradomiciliario, con la aparición o no de focos del mosquito, solamente fue estadísticamente significativo el correspondiente al porcentaje de depósitos con agua no protegidos por manzanas. Se observó una tendencia a la mejoría de las condiciones ambientales intra y extradomiciliarias en las manzanas. El componente ambiental del sistema de vigilancia resultó de utilidad para contribuir a eliminar o disminuir la influencia de condiciones ambientales que pueden favorecer la creación de focos de mosquitos Aedes aegypti. Los resultados de los indicadores intradomiciliarios brindaron elementos que deberán ser empleados en la educación y movilización de la comunidad para la solución de algunos de los problemas detectados. The results of the design and testing of the environmental component of the integrated surveillance system for the prevention and control of dengue fever in “Efraín Mayor'” health area in Cotorro municipality, City of Havana, Cuba, were presented in this paper. The surveillance system was tested in the course of stages 69 th to 76 th of the Campaign for Vectors Control. Seven environmental indicators were used. For data collection, 91-06 statistical form used by the workers of the Campaign was modified, and the observation of new environmental elements in his daily work was incorporated. The blocks were classified by the results of every indicator and two integrated indicators reflecting environmental conditions in and out of the house were developed to facilitating environmental management. In the study of association between summary indicators and the integrated indicator of the inner environment of the house, with or without mosquito foci, it was found that the pe
A dynamic estimation of the daily cumulative cases during infectious disease surveillance: application to dengue fever
Pei-Hung Chuang, Jen-Hsiang Chuang, I-Feng Lin
BMC Infectious Diseases , 2010, DOI: 10.1186/1471-2334-10-136
Abstract: The duration between the date of disease onset and date of laboratory confirmation was assumed to follow a gamma distribution or a nonparametric distribution. A conditional probability of a case being a real case among the unconfirmed cases on a given date was then calculated. This probability along with the observed confirmed cases was integrated to estimate the daily number of new cases and the cumulative number of infected cases.The distribution of the onset-to-confirmation time for the positive cases was different from that of the negative cases. The daily new cases and cumulative epidemic curves estimated by the proposed method have a lower absolute relative bias than the values estimated solely based on the available daily-confirmed cases.The proposed method provides a more accurate real-time estimation of the daily new cases and daily cumulative number of infected cases. The model makes use of the most recent "moving window" of information relative to suspect cases and dynamically updates the parameters. The proposed method will be useful for the real-time evaluation of a disease outbreak when case classification requires a time-consuming laboratory process to identify a confirmed case.Timeliness and accuracy of case reporting are two of the most important performance measures when evaluating an infectious disease surveillance system [1-5]. Laboratory confirmation is usually needed for case diagnosis in many infectious diseases. When laboratory confirmation of the diagnosis is time-consuming, however, there is often a time-lag between the onset date of symptoms and the diagnosis date [6]. For example, the median time for confirmation of the meningococcal disease is about 13 days based on the National Notifiable Diseases Surveillance System (NNDSS) dataset for the United States from 1999 to 2001 [7]. Time from disease onset to diagnosis has been also reported to account for most of the delay in case reporting in Korea [8]. Correct estimation of daily cases or
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