The Jones' Barn strain of Trichomonas gallinae was given to nonimmune pigeons by five different routes: (I) oral; (2) pulmonary; (3) intravenous; (4) intramuscular; (5) subcutaneous. The birds infected by the oral and pulmonarv routes succumbed to typical trichomoniasis involving the liver and lungs respectively. The pulmonary route also produced air sac lesions resulting from trichomonads passing through the lungs via the mesobronchi. Intramuscular and subcutaneous introduction of the parasite resulted in transient infections involving small lesions which were resorbed in I to 2 weeks. The intravenous introductions resulted only in large lesions at the site of inoculation, presumably from perivascular leakage at the time of parasite entry. No other internal lesions were found and cultures made from liver and lung tissue were negative for T. gallinae. The results of infection by the oral and pulmonary routes were not surprising, since these are essentially normal routes of infection. The inhibition of parasite development at the intramuscular and subcutaneous sites of parasite introduction may have resulted from inhibition of the mobility of the parasite by connective tissue or these substrates may have been unsuitable for parasite development. The results of intravenous inoculation are surprising, since it has been stated that T. gallinae reaches the viscera via the circulation. If this were true, lesions should have occurred at least in the lungs where the parasites would have lodged following introduction into a vein. Recovery from infection at any site is apparently sufficient to produce an immunity to the parasite when subsequently introduced via the oral route.
Additional publication details
Influence of inoculation route on the course of infection of Trichomonas gallinae in nonimmune pigeons