High pathogen prevalence in an amphibian and reptile assemblage at a site with risk factors for dispersal in Galicia, Spain

Climate warming triggers the emergence of native viruses in Iberian amphibians

The number of epizootics in amphibian populations caused by viruses of the genus Ranavirus is increasing worldwide. Yet, causes for pathogen emergence are poorly understood. Here, we confirmed that the Common midwife toad virus (CMTV) and Frog virus 3 (FV3) are responsible for mass mortalities in Iberia since the late 1980s. Our results illustrate the Iberian Peninsula as a diversity hotspot for the highly virulent CMTV. Although this pattern of diversity in Europe is consistent with spread by natural dispersal, the exact origin of the emergence of CMTV remains uncertain. Nevertheless, our data allow hypothesizing that the Iberian Peninsula might harbor the ancestral population of CMTVs that could have spread into the rest of Europe. In addition, we found that climate warming could be triggering the CMTV outbreaks, supporting its endemic status in the Iberian Peninsula.

Investigating public support for biosecurity measures to mitigate pathogen transmission through the herpetological trade

The expanding global trade in herpetofauna has contributed to new infectious disease dynamics and pathways that allow for the rapid spread of pathogens geographically. Improved biosecurity is needed to mitigate adverse biodiversity, economic and human health impacts associated with pathogen transmission through the herpetological trade. However, general lack of knowledge of the pathogen transmission risks associated with the global trade in herpetofauna and public opposition to biosecurity measures are critical obstacles to successfully preventing pathogen transmission. In 2019 we administered a survey to 2,007 members of the public in the United States of America to ascertain their support for interventions to prevent the spread of Batrachochytrium dendrobatidis (Bd), Batrachochytrium salamandrivorans (Bsal), ranaviruses, and Salmonella through the herpetological trade. We presented survey respondents with different potential hazards associated with pathogen transmission through this trade, namely ecological, economic, and human health impacts. We used structural equation models to determine how these different hazards and respondents’ characteristics influenced respondents’ support for quarantine and veterinary observation of herpetofauna imported into the United States, mandatory tests for diseases of concern, and best practices to reduce stress and improve the care of live herpetofauna during transport to the United States. Respondents’ values and their perceived susceptibility and sensitivity to different hazards associated with pathogen transmission were key determinants of their support for biosecurity. Respondents with strong biospheric and altruistic values demonstrated sensitivity to ecological and human health impacts associated with pathogen transmission, whereas respondents with strong egoistic values demonstrated sensitivity to economic impacts. Respondents had limited knowledge of Bd, Bsal or ranaviruses, the size of the herpetological trade, or how this trade may contribute to pathogen transmission. Improved outreach and education on pathogen transmission through the herpetological trade is required, but it is important that messages are tailored to people with different values to elicit their support for biosecurity.

Single infection with Batrachochytrium dendrobatidis or Ranavirus does not increase probability of co-infection in a montane community of amphibians

Understanding the occurrence and consequence of co-infections can be useful in designing disease management interventions. Amphibians are the most highly threatened vertebrates, and emerging pathogens are a serious threat to their conservation. The amphibian chytrid fungus and the viruses of the Ranavirus genus are already widely distributed, causing disease outbreaks and population declines worldwide. However, we lack information about the occurrence and consequences of coinfection with these pathogens across age-classes of amphibian hosts. Here, we analyze the occurrence of infection of the amphibian chytrid fungus and ranaviruses during one season in two susceptible amphibian species at two different locations at which outbreaks have occurred. We found that the co-occurrence of both pathogens in a particular host is not common except in highly susceptible life-stages, and that single infections are the most common situation. Moreover, we found that the occurrence of one pathogen in a particular host did not predict the occurrence of the other. We attribute these results to the niches in which both pathogens proliferate in amphibian hosts.