Trichomonas gallinae is a cosmopolitan parasite of birds including finches, pigeons, doves, turkeys, chickens, parrots, and raptors (hawks, golden eagle, etc.).

The protozoa are small (5 to 20 μm size) oval or spherical flagellates with four free flagella found on the anterior aspect of the parasite.

[7] In pigeons, transmission occurs when infected older birds (carriers) feed crop milk to newly hatched squabs.

Turkeys and chickens can become infected through drinking water or food contaminated with feces, saliva or crop secretions.

[8] In young birds, the early lesions appear as small white to yellowish areas in the mouth cavity, especially the soft palate.

Unlike other birds infected with T. gallinae, pigeons are susceptible to secondary organ invasion by virulent strains of the parasite.

In other cases, infected birds may stop feeding, lose weight, look ruffled and dull, and be unable to stand or maintain their balance.

[9] White, sticky plaques may form yellow, necrotic, cheese-like masses on the choana, tongue, or pharyngeal mucosa; there may also be moisture around the beak as well as a foul odor coming from the affected area.

[10] Birds may have difficulty swallowing and breathing due to the cheese-like deposits in the mouth lining and down the esophagus and trachea.

Clinical signs of trichomoniasis include pronounced swallowing motions, excessive salivation and caseous-diphtheritic membranes of the mouth, crop and pharynx.

The infection is confirmed by finding the organism during microscopic examination of the greenish fluids, cheesy material or the lesion.

In psittacine birds, particularly in the early stages of infection, organisms often are not present on wet mounts of oral excretions.

There is a risk of uncontrolled bleeding if oral plaques are removed by forceps, holding open the beak can also suffocate the bird.

Cleaning feeders and bird baths and leaving them dry for a week may help in decreasing spread of disease although natural infections probably occur in the wider environment.

[7] T. gallinae is found all over the world except in Antarctica, Greenland, and the northern parts of North America, Europe, and Asia.