Turkeys and chickens likely become infected through contaminated drinking water or food. Because the trichomonads do not survive for long outside the bird, transmission must occur rapidly. Wild pigeons and other birds may be an important source of introducing the infection to domestic birds. The third method of transmission is more common to birds of prey. An infection may be established in a raptor that has fed on an infected prey bird.
Avian trichomoniasis is principally a disease of young birds.
The severity of the disease depends on the susceptibility of the bird and on the pathogenic potential of the strain of the parasite. Adult birds that recover from the infection may still carry the parasite, but are resistant to reinfection. These birds do not show obvious signs of infection. The lesions consist of inflammation and ulceration of the mucosal surface. The lesions may develop into large, firm necrotic masses that may block the lumen.