Dr. Ritchie's research team has developed serological tests and DNA probes for beak-and-feather disease and polyoma diseases as well as diagnostic tests for avian adenovirus. He has isolated and characterized the viruses that cause psittacine beak-and-feather disease and PVD disease. His research group has also developed a vaccine for Pacheco's disease, Chlamydia, and polyomavirus, which causes a fatal disease in psittacine birds.