Tritrichomonas foetus is a venereal disease in cattle causing early embryonic death and abortion.
The protozoa resides on the surface and in the lumen of the female reproductive tract and in the crypt of penile epithelial cells. Transmission is achieved from infected individuals during mating and direct contact.
T. foetus has no known cyst stage, although carrier cows occur very rarely and the pathogenesis of the carrier state is unknown. Therefore, trophozoites replicate simply by binary fission. It is thought that T. foetus feeds from host lipids and fatty acids [1]
T. foetus is sometimes isolated from foetal gut and lung but this is unlikely to be due to invasion and more likely due to swallowing or inhalation of amniotic fluid in utero.