Trapping and vaccination of endangered Ethiopian wolves to control an outbreak of rabies.
As outbreaks of infectious diseases have emerged as a threat to small populations, conservation managers are increasingly making decisions regarding whether and how to intervene in such situations. Past controversies and lack of knowledge and firm guidelines may inhibit this process. We present data on a vaccination campaign against a rabies outbreak in endangered Ethiopian wolves as a case study of a disease-control intervention in a threatened population. Ethiopian wolves on the periphery of the outbreak area were trapped to administer a dose of injectable rabies vaccine and to assess the magnitude and duration of the immune response. The expansion of an established population monitoring programme allowed us to assess the factors influencing the probability of capturing particular animals and to evaluate the overall success of the intervention. All wolves sampled 1 month after vaccination had protective levels of serum antibody titres. A booster dose administered within 1-6 months appeared to be necessary to maintain these levels. Females were less likely to be trapped than expected, if dispersing females were included in the population. Animals captured in the first trapping session were more likely to be recaptured if the pack was trapped again. The intervention was successful in halting the spread of the rabies outbreak and had few short-term impacts on the population of wolves and non-target species. Synthesis and applications. Demographic, spatial and behavioural heterogeneities within populations may affect vaccine uptake or delivery and thus the efficacy of vaccine-based interventions. Managers of populations of threatened species should ensure that disease-control programmes are carefully designed to maximize information gained on all aspects of an intervention, and thus to evaluate its outcome and impact. Dissemination and discussion of results is crucial in order to apply what has been learnt to similar scenarios in the same or related populations.