1. Maryland Zoo in Baltimore, 1876 Mansion House Drive, Baltimore, Maryland 21217, USA
2. Department of Molecular and Comparative Pathobiology, Johns Hopkins Medicine, 600 N Wolfe Street, Baltimore, Maryland 21287, USA
3. Current address: Department of Biomedical Sciences, Cornell University, College of Veterinary Medicine, Ithaca, New York 14853, USA
4. US National Parasite Collection, Agricultural Research Service, US Department of Agriculture, Animal Parasitic Diseases Laboratory, BARC-East, Building 1180, 10300 Baltimore Avenue, Beltsville, Maryland 20705, USA