Haydon, D. T., Laurenson, M. K., & Sillero‐Zubiri, C. (2002). Integrating epidemiology into population viability analysis: managing the risk posed by rabies and canine distemper to the Ethiopian wolf. Conservation Biology, 16(5), 1372-1385.
Infectious disease constitutes a substantial threat to the viability of endangered species. Population viability analysis (PVA) can be a useful tool for directing conservation management when decisions must be made and information is absent or incomplete. Incorporating epidemiological dynamics explicitly into a PVA framework is technically challenging, but here we make a first attempt to integrate formal stochastic models of the combined dynamics of rabies and canine distemper into a PVA of the Ethiopian wolf ( Canis simensis), a critically endangered canid. In the absence of disease, populations in habitat patches of every size were remarkably stable and persistent. When rabies virus was introduced, epidemics, assumed to arise from sporadic dog-to-wolf transmission, caused extinction probabilities over 50 years to rise linearly with the force of infection from the dog reservoir and particularly steeply in smaller populations. Sensitivity analysis revealed that although the overall pattern of results was not altered fundamentally by small to moderate changes in disease-transmission rates or the way in which interpack disease transmission was modeled, results were sensitive to the process of female recruitment to male-only packs. Completely protecting wolf populations from rabies through vaccination is likely to be impractical, but the model suggested that direct vaccination of as few as 20–40% of wolves against rabies might be sufficient to eliminate the largest epidemics and therefore protect populations from the very low densities that make recovery unlikely. Additional simulations suggested that the affect of periodic epidemics of canine distemper virus on wolf population persistence was likely to be slight, even when modeled together with rabies. From a management perspective, our results suggest that conservation action to protect even the smallest populations of Ethiopian wolves from rabies is both worthwhile and urgent.
Infectious disease constitutes a substantial threat to the viability of endangered species. Population viability analysis (PVA) can be a useful tool for directing conservation management when decisions must be made and information is absent or incomplete. Incorporating epidemiological dynamics explicitly into a PVA framework is technically challenging, but here we make a first attempt to integrate formal stochastic models of the combined dynamics of rabies and canine distemper into a PVA of the Ethiopian wolf ( Canis simensis), a critically endangered canid. In the absence of disease, populations in habitat patches of every size were remarkably stable and persistent. When rabies virus was introduced, epidemics, assumed to arise from sporadic dog-to-wolf transmission, caused extinction probabilities over 50 years to rise linearly with the force of infection from the dog reservoir and particularly steeply in smaller populations. Sensitivity analysis revealed that although the overall pattern of results was not altered fundamentally by small to moderate changes in disease-transmission rates or the way in which interpack disease transmission was modeled, results were sensitive to the process of female recruitment to male-only packs. Completely protecting wolf populations from rabies through vaccination is likely to be impractical, but the model suggested that direct vaccination of as few as 20–40% of wolves against rabies might be sufficient to eliminate the largest epidemics and therefore protect populations from the very low densities that make recovery unlikely. Additional simulations suggested that the affect of periodic epidemics of canine distemper virus on wolf population persistence was likely to be slight, even when modeled together with rabies. From a management perspective, our results suggest that conservation action to protect even the smallest populations of Ethiopian wolves from rabies is both worthwhile and urgent.
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Las enfermedades infecciosas constituyen una amenaza sustancial contra la viabilidad de las especies en peligro. El análisis de viabilidad poblacional ( PVA) puede ser una herramienta útil para dirigir la conservación para el manejo cuando las decisiones deben ser tomadas y la información es escasa o incompleta. La incorporación de dinámicas epidemiológicas explícitamente dentro de una marco PVA es técnicamente un reto; sin embargo, llevamos a cabo el primer intento para integrar modelos estocásticos formales de la dinámica de la rabia y del moquillo canino para un PVA del lobo etíope (Canis simensis), un cánido críticamente amenazado. En ausencia de la enfermedad, las poblaciones que habitan parches de hábitat de todos los tamaños fueron llamativamente estables y persistentes. Cuando se introduce el virus de la rabia, las epidemias, que supuestamente surgen de transmisiones esporádicas de perro a lobo, hicieron que las probabilidades de extinción sobre 50 años se incrementaran linealmente con la fuerza de la infección del perro reservorio y particularmente de manera abrupta en poblaciones pequeñas. El análisis de sensibilidad reveló que a pesar de que el patrón general de los resultados no haya sido alterado fundamentalmente por cambios pequeños o moderados en las tasas de transmisión de la enfermedad ni por la forma en que la transmisión de la enfermedad al interior del grupo fue modelada, los resultados fueron sensibles al proceso de reclutamiento de hembras en grupos de machos. La protección total de las poblaciones de lobos mediante vacunación contra la rabia probablemente no es práctica, pero el modelo sugiere que la vacunación directa de por lo menos un 20-40% de los lobos podría ser suficiente para eliminar las epidemias más grandes y por lo tanto proteger poblaciones con densidades muy bajas que harían poco probable una recuperación. Posteriores simulaciones sugirieron que las repercusiones sobre epidemias de moquillo canino en la persistencia de poblaciones de lobos serían probablemente ligeras, aún cuando se modelaran conjuntamente con la rabia. Desde la perspectiva del manejo, nuestros resultados sugieren que las acciones de conservación para proteger aún a las poblaciones más pequeñas de lobos etíopes de la rabia son importantes y urgentes.
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