Trichomonas gallinae

Trichomonas gallinae is a cosmopolitan parasite of pigeons and doves. Other birds such as domestic and wild turkeys, chickens, raptors (hawks, golden eagle, etc.) may also become infected. The disease in pigeons is commonly called canker. The same condition in birds of prey is called frounce. It is believed to be an ancient pathogen causing frounce-like symptoms in dinosaurs. In 2005, Trichomonas gallinae was first recognized as a cause of disease in British finches, with greenfinch and chaffinch most affected, although a range of garden birds have been found to be susceptible to the parasite. An outbreak in 2017 in Northern France concerned two species, the greenfinch and the goldfinch. Studies have shown that up to a third of adult wood pigeons in Spain may carry the disease. The protozoan has four anterior flagella and an undulating membrane on one side. An important diagnostic feature is the lack of a free posterior flagellum. T. gallinae is generally found in the oral-nasal cavity or anterior end of the digestive and respiratory tracts. The trichomonads multiply rapidly by simple division (binary fission), but do not form a resistant cyst. They therefore die quickly when passed out of the host.