Revista Panamericana de salud Pública/Pan American Journal of Public Health

OBJECTIVE: To determine the most rational strategy of vaccination with Candid 1 vaccine in order to prevent Argentine hemorrhagic fever among children under 15 years old living an endemic area.
METHODS: To analyze the estimated effectiveness, a decision tree model was designed, with two possible options: vaccinate all the children under age 15 in the endemic area ("expanded vaccination") or vaccinate only the children at greater risk ("selective vaccination"). These two options were compared with the alternative of not vaccinating. The evaluation was complemented with a sensitivity analysis to identify the threshold values of the critical variables that could change the decision. The probabilities that were used were taken from earlier clinical and epidemiological trials.
RESULTS: According to the model that we used, the expanded vaccination strategy was the best option, with a total expected utility of 9.99998 (out of a maximum possible 10.0). The sensitivity analysis showed that selective vaccination would be the best strategy if the incidence in the population with low risk drops to less than 3 per 1 000 000 population or if the rate of serious adverse reactions to the vaccine reaches more than 9 per 100 000 inhabitants. No variation in the parameters used in the model supported the option of not vaccinating.
CONCLUSIONS: Given the risk and benefit parameters that we used, we recommend vaccinating with Candid 1 all the children under age 15 who live in the area endemic for Argentine hemorrhagic fever. The proposed model can be fitted to future needs, and it can help in decision-making by incorporating prospective disease surveillance data. These results can be used as a basis for cost and efficacy studies and for other quantitative analyses.

Keywords: Junin virus; hemorrhagic fever, American; decision support techniques; viral vaccines.

OBJETIVO: Determinar la estrategia más racional de vacunación con Candid 1 para prevenir la fiebre hemorrágica argentina (FHA) en los menores de 15 años que viven en el área endémica.
MÉTODOS: Para el análisis de la efectividad estimada se diseñó un modelo de árbol de decisión, con dos posibles opciones: vacunar a todos los menores del área endémica (vacunación ampliada) o vacunar solamente a los menores de 15 años con mayor riesgo (vacunación selectiva). Estas opciones se compararon con la alternativa de no vacunar. La evaluación se complementó con un análisis de sensibilidad para identificar los valores umbral de las variables críticas que podrían modificar la decisión tomada. Las probabilidades empleadas se tomaron de estudios clínicos y epidemiológicos previos.
RESULTADOS: Según el modelo empleado, la estrategia de vacunación ampliada fue la mejor opción, con una utilidad total esperada de 9,99998 (siendo 10 el valor máximo posible). El análisis de sensibilidad demostró que la vacunación selectiva sería la estrategia de mayor utilidad si la incidencia en la población de bajo riesgo se reduce a menos de 3 por 1 000 000 habitantes o si la tasa de reacciones adversas graves a la vacuna asciende a más de 9 por 100 000 habitantes. Ninguna variación de los parámetros empleados en el modelo respaldó la opción de no vacunar.
CONCLUSIONES: Con los parámetros de riesgo y de beneficio empleados, se recomienda vacunar con Candid 1 a todos los menores de 15 años que viven en el área endémica de FHA. El modelo propuesto puede adaptarse a las necesidades futuras y ayudar a tomar decisiones mediante la incorporación de los datos prospectivos de la vigilancia de la enfermedad. Estos resultados pueden usarse como base para estudios de costo y eficacia y para otros análisis cuantitativos.

OBJECTIVES:�Dengue fever is endemic in the country of Grenada and is grossly underreported as a source of morbidity. The goal of this study was to assess the status of dengue fever in a representative community in Grenada.
METHODS:�Surveys were conducted in the Mont Tout/Grand Anse Valley area in the parish of St. George's from March to June 1996. The objectives of the survey were to: (1) to assess the knowledge, attitudes, and practices (KAP) of residents; (2) to determine the presence of larval and adult Aedes aegypti and their potential breeding sites; and (3) to identify the seroprevalence of specific immunoglobulin G (IgG) dengue antibodies in the local population.
RESULTS:�Out of the 102 respondents to the KAP survey, 100 of them (98%) reported never having had dengue fever. Of the 75 persons who agreed to have blood samples taken, 70 of them (93%) (95% confidence interval = 85.1%�97.8%) tested positive with the IgG enzyme-linked immunosorbent assay, indicating past exposure. In terms of water storage, 98 of 102 respondents (96%) stored fresh water in containers. The vector survey found 57 of the 102 households (56%) had Ae. aegypti larvae in water containers on their property, and 94 of 102 dwellings (92%) had adult Ae. aegypti mosquitoes indoors.
CONCLUSIONS:�Although many people were familiar with dengue fever and mosquitoes, the 1996 survey found that their knowledge of the important relationships among mosquitoes, human behavior, and disease transmission was incomplete. Since 1996, continued education efforts have been made in the public school system and with national public health campaigns, yet little effort has been specifically targeted towards our study community. These data suggest Grenada has a need for continued community education that addresses dengue fever transmission and Ae. aegypti reduction.

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El dengue en el pa�s de Granada

OBJETIVOS:��La fiebre del dengue es end�mica en el pa�s caribe�o de Granada y es grande su subnotificaci�n como fuente de morbilidad. El objetivo del presente estudio fue evaluar la situaci�n del dengue en una comunidad representativa de ese pa�s.
M�TODOS: �Se llevaron a cabo encuestas en la zona del valle de Mont Tout y de Grand Anse, en la parroquia de St. George's, de marzo a junio de 1996. Los objetivos de las encuestas fueron: 1) explorar los conocimientos, actitudes y pr�cticas (CAP) de los habitantes; 2) determinar la presencia de formas larvarias y adultas de Aedes aegypti en posibles criaderos, y 3) identificar la seroprevalencia de inmunoglobulina G (IgG) con actividad espec�fica contra el virus del dengue en la poblaci�n local.
RESULTADOS: �De las 102 personas que respondieron la encuesta de CAP, 100 (98%) indicaron que nunca hab�an padecido de fiebre del dengue. De las 75 personas que consintieron que se les sacaran muestras de sangre, 70 (93%) (intervalo de confianza de 95% = 85,1%�97,8%) tuvieron resultados positivos en la prueba de inmunoadsorci�n enzim�tica para la detecci�n de IgG, se�al de que hab�an tenido una exposici�n anterior. En lo que respecta al almacenamiento del agua, 98 de las 102 personas (96%) encuestadas almacenaban agua fresca en recipientes. La encuesta de vectores revel� que en 57 de las 102 viviendas (56%) hab�a larvas de Ae. Aegypti en recipientes de agua en la propiedad, y en 94 de las 102 viviendas (92%) se encontraron mosquitos Ae. aegypti adultos en el interior.
CONCLUSIONES:��A pesar de que muchas personas estaban familiarizadas con la fiebre del dengue y el mosquito vector, la encuesta de 1996 revel� en ellas conocimientos incompletos acerca de las relaciones importantes entre los mosquitos, los h�bitos del ser humano y la transmisi�n de la enfermedad. Desde 1996 se han puesto en marcha de continuo iniciativas educativas en las escuelas p�blicas y mediante campa�as sanitarias a escala nacional, pero pocas han estado dirigidas espec�ficamente a la comunidad aqu� estudiada. Estos datos indican que el pa�s de Granada necesita un sistema de educaci�n comunitaria continua que se oriente a reducir la transmisi�n de la fiebre del dengue y la poblaci�n de Ae. aegypti.

Palabras clave: Dengue; Aedes; conocimientos, actitudes y pr�cticas en salud; control de mosquitos; Grenada.

OBJECTIVE:�Dengue has been endemic in Puerto Rico for three decades. Multiple educational and community-based efforts have been developed to inform the population about dengue prevention. We undertook this study to understand the community members' knowledge, attitudes, and practices related to dengue prevention and to elicit their ideas for future prevention campaigns.
METHODS:�A qualitative study based on grounded theory analysis was conducted between February and May of 2001. The study involved a total of 34 participants in four group interviews who had been identified through the Puerto Rico dengue surveillance system.
RESULTS: �In general, participants had correct knowledge about dengue prevention, but they did not associate the mosquitoes inside their houses with Aedes aegypti. Participants insisted that "neighbors" needed to control larval habitats, and the participants also asked the Government to fumigate.
CONCLUSIONS:�The patterns of knowledge and opinion that emerged in the discussions can be arranged along an axis going from high levels of correct knowledge to low levels of correct knowledge about dengue and dengue hemorrhagic fever and related practices. There were few participants at either extreme. Three themes explained these patterns: misconceptions about dengue (based on previously delivered information), the "invisibility" of dengue (as compared to other diseases), and responsibility (individual and Government). Four strategies for preventive behaviors were recommended: developing community groups to identify community priorities on prevention, developing volunteer groups to deliver prevention messages, making house visits to demonstrate specific control measures, and conducting a complementary media campaign to support these strategies.

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Conocimientos y actitudes en Puerto Rico en torno a la prevención del dengue

OBJETIVO: El dengue ha sido endémico en Puerto Rico durante tres decenios, y varias iniciativas educativas y comunitarias se han puesto en marcha con objeto de informar a la población sobre la prevención de la enfermedad. Realizamos la presente investigación con el fin de entender los conocimientos, actitudes y prácticas de la comunidad en torno a la prevención del dengue y de recoger sus ideas acerca de futuras campañas de prevención.
MÉTODOS: Entre febrero y mayo de 2001 se llevó a cabo un estudio cualitativo basado en el método inductivo conocido por "categorización mediante teoría generada" [grounded theory analysis]. El estudio se efectuó con 34 participantes de cuatro entrevistas en grupo, todos ellos identificados mediante el sistema de vigilancia del dengue de Puerto Rico.
RESULTADOS: En términos generales, los participantes tenían conocimientos adecuados acerca de la prevención del dengue, pero no asociaban los mosquitos que había dentro de las viviendas con Aedes aegypti. Repetían con insistencia que "el vecino" tenía que controlar los hábitat larvarios, y también le pidieron al Gobierno que fumigara.
CONCLUSIONES:  Los conocimientos y opiniones que afloraron en las discusiones mostraron ciertos patrones. Colocados a lo largo de un eje, estos revelaron un espectro desde muchos hasta muy pocos conocimientos que fuesen acertados acerca del dengue, la fiebre hemorrágica del dengue y las prácticas que deben observarse en conexión con estas afecciones. Hubo pocos participantes en un extremo u otro del espectro. Tres temas explicaron los patrones observados: ideas equivocadas en torno al dengue (basadas en información impartida anteriormente), la "invisibilidad" del dengue (por comparación con otras enfermedades), y la responsabilidad (individual y del Gobierno). Se recomendaron cuatro estrategias encaminadas a fomentar conductas de tipo preventivo: crear grupos comunitarios que identificaran las prioridades de la comunidad en materia de prevención; formar grupos de voluntarios que impartieran mensajes con fines preventivos; hacer visitas domiciliarias para demostrar ciertas medidas de control, y llevar a cabo una campaña de publicidad complementaria orientada a reforzar estas estrategias.

Palabras clave: Dengue; educación en salud; Aedes; conocimientos, actitudes y prácticas en salud; control de mosquitos; medios de comunicación de masa; Puerto Rico.

Dengue, a viral disease transmitted by mosquitoes, is endemic and frequently epidemic in many tropical countries. Because low-incidence periods vary in length, it is difficult to know in advance when an epidemic will occur. Response efforts, despite being logical, have been counter-productive at times. Furthermore, experience has demonstrated that dengue epidemics last a long time, making it important that government control efforts be sustainable while they last.
This article describes priority activities requiring attention in order to minimize the impact of dengue epidemics. Such activities, which in many cases can be adapted to combat other types of epidemics as well, are as follows: (1) establishment of an inter-sectoral action committee, (2) formalization of an emergency action plan, (3) epidemiologic surveillance, (4) diagnostic laboratory testing, (5) mosquito control, (6) protection of sources of employment and special populations, (7) patient care, (8) education of medical personnel, (9) research, and (10) transparency before the mass media.
The best way to reduce the ravaging effects of dengue epidemics is to anticipate their emergence so that infection can be prevented and steps can be taken to protect the ill. Relying on improvisation to solve all the problems that arise in moments of crisis is inefficient and reckless.

Dengue and dengue hemorrhagic fever: research priorities

Dengue is one of the most important infectious diseases in tropical and subtropical countries. At present, the only strategy available to reduce the incidence of dengue is vector control. The World Health Organization and the Pan American Health Organization have called on all nations to take the needed steps to help diminish the burden of this disease and its medical and socioeconomic impact. It is hoped that it will be possible to reverse the increase in dengue and help control its spread through a coordinated, effective international response, along with epidemiological, clinical, and virological research that brings together the most advanced methods and techniques. This piece summarizes the most up-to-date information on dengue, analyzes current epidemiologic trends in the Region of the Americas, discusses the main global and Western Hemisphere initiatives to control the disease, and presents the main areas of research that should be developed in the immediate future.

Evaluation of an educational module on dengue and Aedes aegypti for schoolchildren in Honduras

OBJECTIVE: To evaluate the effectiveness of a special course on environmental health and dengue, given to primary school students and intended to promote behavioral changes in the mothers of those students that would lead to the safe handling of water, adequate disposal of trash, and control of household breeding sites of Aedes aegypti, the mosquito vector for dengue.
METHODS: In the period from April to November 2002 a community field trial was carried out that included four public schools in the city of Comayaguela, Honduras. Two of the schools formed the intervention group, and the two others made up the comparison or control group. The data collection activities before and after the intervention included knowledge tests for the schoolchildren and the teachers; surveys of the knowledge, attitudes, and practices of the students' mothers; entomological surveys (systematic checking in order to find water containers, to search for mosquito larvae) in the homes of the schoolchildren; in-depth interviews with the students' mothers; observation in the classrooms; and postintervention focus group with the teachers.
RESULTS: During the intervention period the largest epidemic of classical dengue ever in the history of Tegucigalpa, the capital of Honduras, occurred. That event prompted the Secretariat of Health to undertake large-scale control activities. In the two intervention schools there was a significant increase in the students' knowledge of the following three variables: dengue caused by a virus, life cycle of the vector, and reduction of breeding sites, which is the most effective measure for controlling the vector (P < 0.0001 for all those increases in knowledge). There were also significant increases in the knowledge of the same variables among the teachers in the intervention schools: dengue caused by a virus (P = 0.03), life cycle of the vector (P = 0.01), and reduction of breeding sites (P = 0.004). Reducing the number of breeding sites as being the best measure for controlling Aedes aegypti was the knowledge variable that showed the greatest change among the mothers in the intervention group (P = 0.02). The values for two of the entomological indices (the House index and the Breteau index) were better in the intervention group than in the control group, but the difference was not statistically significant. However, there was a statistically significant difference in the Breteau index values between the two control group schools and the one intervention school where the education course was implemented more adequately than in the other intervention school.
CONCLUSIONS: The application of educational interventions directed to schoolchildren, as a part of a comprehensive plan for controlling Aedes aegypti, is an effective way to raise the awareness of teachers and parents with respect to the problem of dengue, and it also helps in encouraging family members to be involved in reducing breeding sites in the home. In moving to control the dengue vector, this strategy should take into consideration the involvement not only of families but also of civic and public institutions in the community. Given our results, it appears that this approach of using a special course for schoolchildren can constitute a fundamental pillar in the strategy for integrated dengue control.

OBJETIVOS: Evaluar la eficacia de un curso sobre salud ambiental y dengue, impartido a alumnos de primaria y encaminado a promover en las madres de familia cambios de comportamiento que lleven a un manejo seguro del agua, a la disposición adecuada de la basura y al control de los criaderos domésticos de Aedes aegypti, el mosquito vector de la enfermedad.
MÉTODOS: En el período de abril a noviembre de 2002 se llevó a cabo un ensayo de campo comunitario que incluyó cuatro escuelas públicas de la ciudad de Comayaguela, Honduras, dos de las cuales formaron el grupo de intervención (GI) y las otras dos el grupo testigo o de control (GC). Las actividades de recolección de información pre y posintervención incluyeron pruebas de conocimiento a escolares y maestros, encuestas de conocimientos, actitudes y prácticas a madres de familia, encuestas entomológicas (registro sistemático para encontrar depósitos que contengan agua, en busca de larvas de mosquitos) en las viviendas de los escolares, entrevistas a profundidad a madres de familia, observaciones participativas en las aulas y un grupo focal posintervención con los maestros.
RESULTADOS: Durante el período de la intervención se presentó la mayor epidemia de dengue clásico en la historia de la ciudad capital, que motivó actividades de control a gran escala por parte de la Secretaría de Salud. En el ámbito escolar, el GI mostró un incremento significativo en el conocimiento de los alumnos en las siguientes variables: dengue causado por un virus (78,5% frente a 56,6%), ciclo de vida del vector (79,4% frente a 23,6%) y reducción de fuentes —la medida más eficaz de control del vector— (85,2% frente a 58,1%); los incrementos en todas las variables tuvieron un valor P <0,0001. También en el conocimiento de los maestros del GI se obtuvieron resultados significativos en las mismas variables: dengue causado por un virus (80,0% frente a 30,0%; P= 0,03), ciclo de vida del vector (70,0% frente a 20,0%; P= 0,01), reducción de fuentes (90,0% frente a 40,0%; P= 0.004). La reducción de fuentes, como mejor medida de control de Aedes aegypti,fue la variable de conocimiento que mostró mayor cambio en las madres del GI (75,1% frente a 65,6%; P= 0,02). El cálculo de los índices entomológicos (GI: índice de viviendas [IV] 23,4 e índice de Breteau [IB] 30,5, frente a GC: IV 26,5 e IB 38,1) reveló reducción de estos en las comunidades intervenidas, aunque no en grado estadísticamente significativo. Sin embargo, en comparación con el GC, solo en la escuela donde el curso se aplicó adecuadamente fue posible lograr un cambio significativo en el índice de Breteau.
DISCUSIÓN: La aplicación de intervenciones educativas dirigidas a escolares como parte de un plan integral para el control de Aedes aegypticonstituye una manera eficaz de sensibilizar a maestros y padres de familia respecto al problema del dengue, y coadyuva a inducir su participación en la reducción de fuentes en el ámbito domiciliario. Esta estrategia deberá considerar el compromiso, no solo de las familias, sino también de las instituciones cívicas y públicas de la comunidad, hacia el objetivo de controlar este vector.
De acuerdo con los resultados, este método, aplicado por medio de un curso para escolares, puede constituir un pilar fundamental en la estrategia para el control integrado del dengue.

Final characterization of and lessons learned from the dengue 3 epidemic in Cuba, 2001–2002

Over the past 10 years, the American Region has witnessed the reintroduction and dissemination of dengue virus serotype 3. In this paper we describe the main clinical and epidemiologic features of the dengue 3 epidemic that broke out in Cuba between June 2001 and March 2002, as well as the measures that were undertaken to eliminate it. A total of 14 524 confirmed cases were reported, 12 889 (88,7%) of them in the City of Havana. Eighty one cases of dengue hemorrhagic fever were confirmed, three of which died. Secondary infection, white skin color, sickle cell anemia, and bronchial asthma were risk factors for dengue hemorrhagic fever. Active clinical and epidemiologic surveillance and laboratory support were critical to the early detection of transmission and to the monitoring of the epidemic. Widespread involvement of the community and its different sectors, participation of the mass media with a single leadership in command, and strong political will were the key factors that made it possible to eliminate transmission. This epidemic was one more example of the risk of dengue epidemics faced by countries in the area, including those that have strong surveillance and control programs. It also served to show that by applying the principles established by the Pan American Health Organization and the World Health Organization for dengue control, transmission can be stopped.

Economic impact of dengue and dengue hemorrhagic fever in the State of Zulia, Venezuela, 1997–2003

Objectives. To determine the direct and indirect costs of medical care provided to cases of dengue and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) between 1997 and 2003 in Zulia State, Venezuela.
Methods. The total number of patients with dengue and DHF/DSS was obtained from records belonging to the Regional Epidemiology Office of the state of Zulia and from reports of cases that were confirmed in the Virology Section of Dr. Americo Negrette’s Clinical Research Institute, Zulia University, Maracaibo, Venezuela, between 1 January 1997 and 31 December 2003. Direct costs included the cost of emergency medical care for all cases and hospital costs for cases with DHF/DSS (cost per bedday and laboratory expenses). The costs connected to absence from work among patients over 15 years of age and mothers who accompanied their children under 15 years of age comprised the indirect costs, which were adjusted for the proportion of men and women in the labor force. Calculations were based on the minimum yearly wage, and results were given in United States dollars, converted according to each year’s average exchange rate.
Results. During the study period, 33 857 cases of dengue and DHF/DSS were seen. Of them, 30 251 (89.35%) were cases of dengue, and 3 606 (10.65%) were cases of DHF/DSS. Six cases of DHF/DSS died (lethality rate: 0.2 per 100 cases of DHF/DSS). Direct costs were US$ 474 251.70; of these costs, US$ 132 042.30 were spent on emergency medical care and US$ 342 209.40 on the hospital costs of DHF/DSS cases. Indirect costs were US$ 873 825.84 and comprised 64.8% of overall expenditures (US$ 1 348 077.54) connected to this disease during the study years.
Conclusions. This is the first study on the economic impact of dengue in the state of Zulia and in Venezuela. In spite of some limitations, results show that dengue is an important public health problem that causes great expense because of temporary absenteeism from work and that undermines regional and national economic development.

Objetivos. Determinar los costos directos e indirectos asociados con la atención de los casos de dengue y de dengue hemorrágico o síndrome de choque por dengue (DH/SCD) entre los años 1997 y 2003 en el Estado de Zulia, Venezuela.
Métodos. El número total de pacientes con dengue y DH/SCD se obtuvo de los registros de la Dirección Regional de Epidemiología del Estado de Zulia y de los informes de casos confirmados en la Sección de Virología del Instituto de Investigaciones Clínicas Dr. Américo Negrette, de la Facultad de Medicina, Universidad del Zulia, Maracaibo, entre el 1.° de enero de 1997 y el 31 de diciembre de 2003. Como costos directos se consideraron el costo de la atención médica de urgencia de todos los casos y los costos de hospitalización de los casos con DH/SCD (costo por día-cama y costos de laboratorio). Los costos asociados con la ausencia laboral de los enfermos mayores de 15 años y de las madres acompañantes de los enfermos menores de 15 años conformaron los costos indirectos, ajustados según la proporción de hombres y mujeres en la fuerza laboral activa del país. Para el cálculo se utilizó el salario mínimo anual y los resultados se expresaron en dólares estadounidenses, según la tasa de cambio promedio de cada año.
Resultados. En el período estudiado se atendieron 33 857 casos de dengue y de DH/SCD; de ellos, 30 251 (89,35%) fueron de dengue y 3 606 (10,65%) de DH/SCD. Seis de estos fallecieron (letalidad 0,2 por 100 casos de DH/SCD). Los costos directos fueron US$ 474 251,70; de esa suma, US$ 132 042,30 correspondieron a la atención en los servicios de urgencia y US$ 342 209,40 a los gastos de hospitalización de los casos con DH/SCD. Los costos indirectos ascendieron a US$ 873 825,84 y representaron 64,8% del gasto total (US$ 1 348 077,54) relacionado con esta enfermedad en los años estudiados.
Conclusiones. Este es el primer estudio acerca del impacto económico del dengue en el Estado de Zulia y en Venezuela. A pesar de que el estudio tuvo algunas limitaciones, los resultados demuestran que el dengue constituye un importante problema de salud pública que ocasiona grandes gastos por ausentismo laboral temporal y que afecta considerablemente al desarrollo de la economía regional y nacional.

Risk perception and strategies for mass communication on dengue in the Americas

Dengue is clearly a very serious public health problem. In the Americas the number of dengue cases has been increasing since the 1960s, and outbreaks of the disease have been occurring more frequently. Furthermore, the density of infestation with the disease vector, the Aedes aegypti mosquito, is high in the Americas. The general strategy for preventing and controlling dengue and dengue hemorrhagic fever is based on promoting behavior changes that lead to incorporating the community in controlling the disease, particularly the vector. In order to achieve this, mass communication programs on dengue should have two primary aims: converting information into practice and encouraging the community to take over prevention and control measures. The new generation of programs should be designed based on the local sanitation structure (water distribution and waste disposal) as well as information on community organizations and the roles of different family members. Furthermore, the new programs should incorporate all the following ten components: epidemiological surveillance, intersectoral actions, community participation, managing the environment and basic services, patient care, case reporting, education, using insecticides and vector control, training, and preparing for emergencies. Communication should be aimed at modifying the behavior of individuals and the community by empowering them to carry out prevention and control measures.