All imported birds that are not of U.S. or Canadian origin must undergo a 30-day quarantine in a U.S. Department of Agriculture animal import quarantine facility. The quarantine is mandatory and at the owner's expense. Birds are immediately placed in incubators called isolettes that control the spread of disease and prevent cross-contamination by strategically placed High Efficiency Particulate Air (HEPA) filters. Before each quarantined bird is cleared for release, it is tested for Avian Influenza and Exotic Newcastle Disease.