Emerging Pathogens and Stress Syndromes of Cetaceans in European Waters

There is a growing awareness among the veterinary and human health disci- plines of the importance of the link between human and animal health and envi- ronmental conditions, particularly in the context of species conservation (Deem et al., 2001; Aguirre et al., 2012). Connections between the health of humans, animals, and the environments in which they live are well recognized and have been referred to as “one health, one medicine.” Pathogens may use many different methods to disperse from an infected to an uninfected host. As a consequence, factors that affect these pathogens, hosts, and vectors, and their probability of close contact, are fundamentally crucial to dis- ease dynamics. Several ecologic processes influence risk and disease incidence. Environmental changes due to anthropogenic activity such as climate change and pollution have been associated with disease states in human and animal populations. Pathogens, along with habitat loss, overexploitation, human distur- bance, and pollution, are becoming more important factors in the conservation of species (Lafferty and Gerber, 2002; Smith et al., 2006). In some marine mam- mal mass mortality events (Heide-Jørgensen et al., 1992; Houde et al., 2005) and epidemics of infectious diseases in amphibians and reptiles (Herbst, 1994; Berger et al., 1998), environmental pollution has been hypothesized to be a rel- evant causative factor. To evaluate impacts of pollution on cetaceans’ health and its role on the epidemiology of infectious diseases, it is important to investigate routinely stranding events. In fact, cetacean strandings are an important source of information on cetacean population health status, allowing determination of not only the causes of mortality but also the threats to these populations, includ- ing anthropogenic and natural risks (Peltier et al., 2014). Global contamination has become a great concern, especially for cetaceans because they are one of the populations exposed to highest concentrations of persistent organic pollutants (POPs) arising out of an alarming anthropo- genic pressure (Tanabe, 2002). Although the use of the majority of the toxic chemicals detected in cetaceans is currently banned, relevant levels still per- sist in the environment, accumulate in lipid-rich tissue, and build up along trophic levels, therefore affecting populations of cetaceans all over the world. Besides, various authors have attempted to establish thresholds for toxicity in different tissues (Kannan et al., 2000; AMAP, 2002; Letcher et al., 2010), and numerous studies have shown that these endpoints are commonly exceeded in marine mammals.