Infectious pathogen risk stemming from U.S. exotic animal imports and exporting countries

The recent outbreak of Batrachochytrium salamandrivorans in many European salamander populations—resulting from introduced Asian salamanders—highlights the risk to native wildlife from international trade of live animals.... [ view full abstract ]

The recent outbreak of Batrachochytrium salamandrivorans in many European salamander populations—resulting from introduced Asian salamanders—highlights the risk to native wildlife from international trade of live animals. In 2014, over 130 million exotic vertebrate animals were imported into the United States from 126 countries, without any disease surveillance, primarily for the booming pet industry. Imported animals, either wild-sourced or captive-bred, can harbor infectious pathogens harmful to native U.S. wildlife if accidentally or deliberately released into the wild. It is reasonable to assume that risk of importing infectious pathogens varies according to conditions in the exporting countries and is a function of the number of imported species and individuals per country. To better understand disease risk, we examined 17 years of USFWS import data and quantified composition, magnitude, and source (i.e., exporting country) of live bird, mammal, reptile, amphibian and fish imports. We created an export-country level infectious disease threat index by regressing the number of annual reportable disease outbreaks against socio-economic and ecological variables that facilitate outbreaks. Using the concept of propagule pressure, we evaluated the threat index along with the abundance of species and individuals exported from each country to prioritize which country-host combinations carried the highest risk of harboring infectious pathogens. On average, 750 genera, 1,120 species, and 185 million individuals were imported annually, with fish comprising almost 97% of imports. Sixty percent of annual imports were captive-bred individuals; reptiles were the most abundant wild-sourced taxa (70%). Over 200 countries exported live animals to the U.S. during the study period with roughly 40% exporting annually. Southeast Asian countries dominated the export trade and ranked high for infectious pathogen risk. These results are being used in a broader pathogen trait-based import risk assessment.