Trichomoniasis is caused by infection with the parasitic protozoa Trichomonas gallinae. This protozoa has variable pathogenicity (ability to cause disease). Transmission of the protozoa is by bird to bird contact or by contact with infected litter, feed or water. The protozoa is shed in the faeces of infected birds and can be regurgitated in crop milk.
Treatments are available that will control the disease but there may be restrictions on their use in commercial flocks. Prevention requires good biosecurity and management practices to eliminate the sources of infection. Drain water pools on ranges, screen out wild birds, separate young birds from adults as well as susceptible birds from recovered (carrier) birds.
Poultry Health Handbook 4th Ed, 1994. L. D. Schwartz, Pennsylvania State University.