Causes and Susceptible Species
Trichomoniasis is caused by the flagellate protozoan Trichomonas gallinae. It is the most common disease finding in mourning doves, occasionally causing mortality over sizeable geographic areas. Other dove species are variably susceptible. It is thought that T. gallinae came to North America with Rock (Common) Pigeons accompanying European settlers. Trichomoniasis is occasionally diagnosed in raptors that consume infected doves. Falconers have historically referred to this disease in their birds as frounce.
Symptoms, Diagnosis and Transmission
T. gallinae is a parasite of the upper alimentary canal, most commonly the mouth and upper esophagus. Virulent strains produce cheesy necrotic lesions that may block passage of food and impair breathing. Sick doves appear depressed and oral lesions may show externally as bulges beneath the head.
Trichomoniasis is tentatively diagnosed from the gross lesions. Observation of the live flagellated trichomonad in saliva or lesion scrapings is confirmatory. Fresh unfrozen specimens are required for confirmation in this manner.
Adult doves may transmit the parasite directly to their young via crop milk (doves produce a milk-like substance in their crops which they feed to their young). Transmission via food and water contaminated by sick birds may be important.
Threats to Other Species or Humans
Trichomoniasis is by far the most important disease of mourning doves. Despite some initial concerns, trichomoniasis did not prove to be a significant problem during the reintroduction of Peregrine Falcons to large cities where Rock Doves were the principal prey. T. gallinae poses no threat to human health.