The present invention relates to the use of protease inhibitors, especially cysteine protease inhibitors. Trichomonas gallinae is a flagellated protozoan parasite which infects a variety of birds all over the world. Avian trichomonosis, caused by T. gallinae, has been reported from several continents as a major disease for numerous avian species of the orders Columbiformes, Falconiformes and Psittacifomes. They may infect other avian species as well, like Galliformes and Passeriformers. The domestic pigeon (Columba livia) is the primary host of this flagellate which has been considered responsible for the worldwide spread of T. gallinae. Furthermore, serious losses among wild birds, in particular wild finches, due to T. gallinae were reported recently. T. gallinae colonizes mainly in the upper digestive tract of the birds, where, it can cause granulomatous lesions that occlude the oesophagus lumen, leading to the death of birds as a result of severe starvation. The parasite produces a variety of pathological changes depending on the virulence
of the strain and the species of bird infected. Earlier studies with T. gallinae have demonstrated a wide spectrum of virulence among different T. gallinae strains. Accordingly, some T. gallinae strains do not cause clinical signs and can induce certain immunity against a highly virulent one. Virulent strains are able to produce a systemic infection in its host and affect mainly the liver and lung beside the oropharynx. Pathological changes following experimental infection of a pigeon with a virulent strain of T. gallinae were described in detail in the prior art. |
