Studies on Trypanosoma avium Danilewsky 1885 III. Life Cycle in vertebrate and invertebrate hosts

Abstract

1. The life cycle of Trypanosoma avium in both its hosts is described.2. In the vector (Ornithomyia avicularia) it undergoes a cyclical development in the alimentary canal. Multiplication occurs while the flagellate is in the crithi-dial stage, and, finally, pyriform haptomonad crithidia appear in the insect's hind-gut: these change into the infective metacyclic trypanosomes.3. After penetrating the mucous membranes of the bird (following its ingestion of the louse-fly), the metacyclic trypanosomes probably invade the lymph system, and there develop (by growth alone) into the large forms seen in the bird's blood some 18–24 hr. later.4. The trypanosomes persist in their natural hosts (but not in canaries) throughout the winter, more-or-less restricted to the bone-marrow. In the spring they reappear in the peripheral blood.