In this post Associate Editor Céline Bellard discusses the recent paper ‘Managing the risk of wildlife disease introduction: pathway-level biosecurity for preventing the introduction of alien ranaviruses‘, by Pablo García-Díaz, Joshua Ross, Andrew Woolnough and Phillip Cassey.

Invasive alien species are one of the major drivers of global biodiversity loss. Among the most notorious invasive species, emerging wildlife diseases like the chytrid fungi are a globally widespread threat to native amphibian species. Emerging wildlife diseases have been responsible for putting hundreds of species at risk of population extinction, with no sign of slowing down. Rapid declines in amphibian populations have occurred around the world.

In order to combat this threat, it is now widely recognized that early detection and rapid response is one of the critical defences against the establishment of invasive species. In particular, one of the most efficient ways to reduce the risk of new invasions is to implement stringent biosecurity measures. For instance, border and post-border surveillance are particularly recommended to prevent new introductions of emerging diseases.

To address this risk, Australia has a number of screening, surveillance and quarantine measures in place to manage the risk of unintentional transport of infected alien amphibians. Yet the capacity of such measures to limit new introductions has seldom been evaluated. This is symptomatic of invasion biology generally, but it is critical that evidence-based research is adopted to inform managers, and incorporate the assessment of optimal surveillance and biosecurity strategies.

García-Díaz et al. assessed the capacity of Australian border and post-border biosecurity activities to prevent the introduction of alien ranaviruses. They collected information on 287 detections of alien amphibian individuals detected on both airplanes and ships arriving in Australia. By developing a hierarchical model to describe transport pathways into Australia and the biosecurity measures that are implemented, they assessed the capacity of existing biosecurity activities to act as an effective barrier against ranaviruses.

Their conclusion is unequivocal: border and post-border biosecurity programs in Australia reduced the risk of introduction of alien ranaviruses.  García-Díaz et al. provide a clear illustration of the effectiveness of the Australian biosecurity system to detect potential introduction of alien ranaviruses via the unintentional transport of alien amphibians. Their work draws attention to the fact that such programs are efficient and should be implemented in other countries to continue prevention of emerging diseases.  This study highlights again that an international response to fight emerging diseases is highly recommended, entirely necessary, and could be efficient to prevent future invasions. Moreover, their work encourages further research to assess other early detection measures against invasive species and identify their gaps to improve further our capacity to combat invasive species.

A common midwife toad (Alytes obstetricans) that died during a ranavirus outbreak, Galicia, North-western Spain. Ranavirus outbreaks have produced die-offs in amphibian populations all over the world, and the research by García-Díaz et al. demonstrates that implementing biosecurity activities reduce the risk of introduction of alien ranaviruses. Photo credit Marius Von Essen.

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