Amphibians are experiencing devastating population declines globally. A major driver is chytridiomycosis, an emerging infectious disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). Bd was described in 1999 and has been linked with declines since the 1970s, while Bsal is a more recently discovered pathogen that was described in 2013. It is hypothesized that Bsal originated in Asia and spread via international trade to Europe, where it has been linked to salamander die-offs. Trade in live amphibians thus represents a significant threat to global biodiversity in amphibians. We review the current state of knowledge regarding Bsal and describe the risk of Bsal spread. We discuss regional responses to Bsal and barriers that impede a rapid, coordinated global effort. The discovery of a second deadly emerging chytrid fungal pathogen in amphibians poses an opportunity for scientists, conservationists, and governments to improve global biosecurity and further protect humans and wildlife from a growing number of emerging infectious diseases.

Emerging diseases are increasing burdens on public health, negatively affecting the world economy, causing extinction of species, and disrupting ecological integrity. One Health recognizes that human, domestic animal, and wildlife health are interconnected within ecosystem health and provides a framework for the development of multidisciplinary solutions to global health challenges. To date, most health-promoting interventions have focused largely on single-sector outcomes. For example, risk for transmission of zoonotic pathogens from bush-meat hunting is primarily focused on human hygiene and personal protection. However, bush-meat hunting is a complex issue promoting the need for holistic strategies to reduce transmission of zoonotic disease while addressing food security and wildlife conservation issues. Temporal and spatial separation of humans and wildlife, risk communication, and other preventative strategies should allow wildlife and humans to co-exist. Upstream surveillance, vaccination, and other tools to prevent pathogen spillover are also needed. Clear multi-sector outcomes should be defined, and a systems-based approach is needed to develop interventions that reduce risks and balance the needs of humans, wildlife, and the environment. The ultimate goal is long-term action to reduce forces driving emerging diseases and provide interdisciplinary scientific approaches to management of risks, thereby achieving optimal outcomes for human, animal, and environmental health.

Background and Significance Chronic wasting disease (CWD) is an emerging infectious disease that is fatal to free-ranging and captive animals in Cervidae (the deer family; referred to as "cervids"). Affected animals include some Odocoileus, Cervus, and Muntiacus species (deer), Cervus canadensis (elk), Alces alces (moose), and Rangifer tarandus (reindeer). Once an animal is infected, CWD typically causes neurological damage that grows more severe until the host animal dies. Originally identified in 1967, to date (early 2018), the disease has been found in 24 States as well as Canada, South Korea, and Norway. It continues to spread across North America through new and ongoing outbreaks (fig. 1). In addition, the proportion of CWD-infected animals is increasing in many areas where the disease is already established. For example, the proportion of adult male and female Odocoileus virginianus (white-tailed deer) in north-central Iowa County, Wisconsin, that tested positive for CWD has more than doubled during a 6-year period (2011-16). Approximately 40-50 percent of the adult male population and 20-30 percent of the adult female population was infected by 2016, making north-central Iowa County one of the most heavily affected regions in the United States (Wisconsin Department of Natural Resources, 2017). In some heavily affected areas, total cervid numbers have decreased over time due to CWD, which suggests that these cervid populations may not be sustainable in

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