Cellular immunological responses of pheasant during endogenous development of Eimeria colchici

We examined the time course and histological localisation of the developmental stages of Eimeria colchici. The prepatent period in the caeca of pheasants was 6 days. The patent period began on day 7 post-infection (p.i.) and ended on day 11 p.i. with peak production of oocysts on days 8-9. The peripheral blood lymphocytes of pheasant chicks showed a significant increase in proliferation to E. colchici antigen from day 5 p.i., with peak on day 14 p.i. The metabolic activity (respiratory burst) of heterophils increased on days 3, 4 and 14 p.i. The total number of peripheral blood leukocytes and lymphocytes in the infected pheasant chicks had increased by day 2 p.i. and reached a maximum on day 4 of the experiment. Days 5 and 6 p.i. were characterised by a drop in the number of these cells.