Major disease threats to European amphibians

Disease threats to amphibians in Europe are generally poorly understood. The effects that disease can have on amphibian populations can range from minimal to local extirpation. Currently, two infectious agents are emerging as disease threats to European amphibian populations: Batrachochytrium dendrobatidis (Bd), which is the causative agent of amphibian chytridiomycosis, and ranavirus(es). Both pathogens are listed by the World Organization for Animal Health (OIE). The incidence of other infectious diseases, such as amphibiocystidium, might also be increasing. In this review, we discuss known and potential disease threats to European amphibians, including their current and potential impact on amphibian populations, and factors driving their emergence and spread. We provide recommendations on how to proceed with investigations into cases where disease is thought to be involved in mortality or decline. We also stress that a multidisciplinary approach to these investigations is required.