Evaluación de riesgos aplicado a la prevención y la vigilancia de la encefalopatía espongiforme bovina (EEB) en los países de la región de las Américas / Risk assessment applied to the prevention and surveillance of bovine spongiform encephalopathy (BSE) in the countries of the Americas region

Se desarrolló un modelo bayesiano para evaluación de riesgos de EEB. Conjuga registros y opinión experta con datos de muestreo. Se compararon percentiles de probabilidad de EEB obtenidos con la evaluación de riesgo, muestreo y Bayes a partir de datos de Argentina y de escenarios hipotéticos. Bajo un escenario hipotético de incertidumbre, la importancia del muestreo y de la estimación bayesiana fue evidente. Los resultados ratifican la coherencia del Código de OIE y la condición de Argentina de riesgo insignificante y muestran la conveniencia de aplicar regularmente modelos similares.(AU)

A Bayesian model for BSE risk evaluation was developed. It conjugates records and expert opinion with sampling data. EEB probability percentiles by sampling, risk evaluation and Bayes were compared using data from Argentina and from hypothetical scenarios. Under a scenario of uncertainty, sampling and Bayesian estimation importance was evident. Results ratify coherence of the OIE Code and Argentinean condition of insignificant risk and show the convenience of applying similar models regularly.(AU)

Rabies transmitted by vampire bats to humans: an emerging zoonotic disease in Latin America? / La rabia transmitida por murciélagos vampiros a humanos: ¿una zoonosis emergente en América Latina?

Human rabies transmitted by vampire bats reached new heights in Latin America in 2005. A total of 55 human cases were reported in several outbreaks, 41 of them in the Amazon region of Brazil. Peru and Brazil had the highest number of reported cases from 1975 to 2006. In Peru, outbreaks involving more than 20 cases of bat-transmitted human rabies were reported during the 1980s and 1990s. During this period, a smaller number of cases were reported from outbreaks in Brazil. A comparison of data from field studies conducted in Brazil in 2005 with those from the previous decade suggests similar bat-bite situations at the local level. The objective of this study was to review the epidemiological situation and, on the basis of this information, discuss possible factors associated with the outbreaks. Prevention and control measures already recommended for dealing with this problem are also reviewed, and some further suggestions are provided.

La rabia en humanos transmitida por murciélagos vampiros aumentó en América Latina en 2005. Se notificaron varios brotes con un total de 55 personas enfermas, 41 de ellas en la región amazónica de Brasil. Perú y Bolivia acumularon el mayor número de casos notificados entre 1975 y 2006. En Perú se informaron brotes de más de 20 personas con rabia transmitida por murciélagos en las décadas de 1980 y 1990. En ese período se informó un número menor de casos en los brotes de Brasil. Al comparar los datos de estudios de campo realizados en Brasil en 2005 con los obtenidos en décadas anteriores se observaron situaciones similares en cuanto a los casos de mordidas por murciélagos a nivel local. En este estudio se presenta una revisión de la situación epidemiológica y, a partir de esa información, se discuten los posibles factores asociados con los brotes. Se revisan también las medidas de prevención y control ya recomendadas para hacer frente a este problema y se ofrecen algunas recomendaciones adicionales.

Current status of human rabies transmitted by dogs in Latin America

Latin American countries made the political decision to eliminate human rabies transmitted by dogs by the year 2005. The purpose of the current study is to evaluate to what extent this goal has been reached. The epidemiological situation and control measures were analyzed and broken down within the countries by georeferencing. The 27 human cases reported in 2003 occurred in some 0.2 percent of the second-level geopolitical units (municipalities or counties) in the region, suggesting that the disease is a local problem. Several areas within the countries reported no more transmission of rabies in dogs. Nearly 1 million people potentially exposed to rabies received treatment. On average, 34,383 inhabitants per health post receive anti-rabies treatment (range: 4,300-148,043). Nearly 42 million dogs are vaccinated annually. Surveillance is considered fair according to the epidemiological criteria adopted by the study. Samples sent for rabies testing represent 0.05 percent of the estimated canine population (range: 0.001 to 0.2 percent). The countries are quite close to achieving the goal.

Os países da América Latina tomaram a decisão política de eliminar a raiva humana transmitida por cão até 2005, e o objetivo deste estudo é analisar o cumprimento desta meta. A situação epidemiológica e as ações de controle foram analisadas de forma desagregada dentro dos países, utilizando-se georreferenciamento da informação. Os 27 casos humanos relatados em 2003 ocorreram em cerca de 0,2 por cento das unidades de segundo nível geopolítico (municípios) da região. Esse dado sugere que a doença atualmente é muito localizada. Vários países não reportam mais transmissão de raiva em cães. Cerca de 1 milhão de pessoas são potencialmente expostas ao risco da raiva e recebem atendimento médico. Existem em média 34.383 (classe: 4.300-148.043) habitantes por posto de saúde com tratamento anti-rábico. São vacinados cerca de 42 milhões de cães anualmente, 70 por cento deles no Brasil e México. A vigilância epidemiológica para a raiva foi considerada média pelos critérios estabelecidos no estudo, sendo enviada 0,05 por cento da população canina estimada de amostras para diagnostico de raiva. Foi considerado que os países estão muito próximos de alcançar a meta.

Estudio de la performance del modelo Covello-Merkhofer en la medición del riesgo en planes de vacunación antiaftosa / Performance study of the Covello-Merkhofer model in the treatment of risk in anti-footprint vaccination plans

La cíclica y masiva movilización de terneros puede determinar la recurrencia y persistencia de fiebre aftosa. Por ello, en Sudamérica se promueven esquemas de vacunación en función de la dinámica ganadera. Para evaluar mejor estos esquemas se desarrolló y aplicó un modelo estadístico de cuantificación de riesgos para asistir en la evaluación de planes de vacunación sistemática contra la fiebre aftosa de bovinos. El modelo utiliza información sobre la epidemiología de la fiebre aftosa; de la dinámica poblacional y de vacunación recolectada en un período llamado Ventana de Observación/Estimación y la proyecta hacia una fecha futura ubicada en un período llamado Ventana de Predicción en donde se obtuvo un predictor de la probabilidad de contacto entre terneros no vacunados y bovinos residualmente infectados por el virus de la fiebre aftosa. El modelo utiliza estimación de parámetros obtenidos de la opinión experta; de evidencias empíricas; o de la conjugación de ambos mediante estimadores bayesianos de las distribuciones Beta y Dirichlet. El modelo se aplicó a datos de Argentina mediante simulación de Monte Carlo, permitiendo identificar diferencias significativas al 5% entre los efectos de tres alternativas de vacunación comparadas mediante el método de Bonferroni.(AU)

The recurrence and persistence of fmd could be the consequence of cyclic and massive transportation of calves. For this reason, vaccination schemes related to livestock dynamic are promoted in South America. To improve the evaluation of vaccination schemes a quantitative stochastic risk assessment model was developed and applied in order to aid in the evaluation of strategies of systematic vaccination of cattle against fmd. The model uses information about fmd epidemiology and about population and vaccination dynamics. The information is collected during a period of time called Observation/Estimation Window and projected to a later time called Prediction Window where a predictor of the probability of contact between non-vaccinated calves with residually fmd infected cattle is obtained. Estimates of the parameters of the model are obtained from: expert opinion; empirical evidence or the conjugation of both by means of Bayesian estimators of the Beta and Dirichlet distributions. Applied to data of Argentina, through Monte Carlo simulation, the model allowed the identification of significant statistical differences among the effects of three different vaccination alternatives compared by Bonferroni test.(AU)