The United States is among the world's largest importers of live wild animals (4) and imported >1 billion indi-vidual animals during 2000-2004 (5) . Little disease surveillance is conducted for imported animals; quarantine is required for only wild birds, primates, and some ungulates arriving in the United States, and mandatory testing exists for only a few diseases (psittacosis, foot and mouth disease, Newcastle disease, avian infl uenza). Other animals are typically only screened for physical signs of disease, and pathogen testing is delegated to either the US Department of Agriculture (for livestock) or the importer (6) . The process of preimport housing and importation often involves keeping animals at high density and in unnatural groupings of species, providing opportunities for crossspecies transmission and amplifi cation of known and unknown pathogens. Thus, imported wildlife remain a major public health threat, as exemplifi ed by the importation of Ebola virus in primates from the Philippines (7), monkeypox from imported African rodents (8) , and possibly HIV from chimpanzees in central Africa (9) . Wildlife importation also poses a great threat to domestic wildlife and the US agriculture industry (5) .