Abstract
Systemic and acute infection with Chlamydia (C.) psittaci avian strains was established in 8-day-old White Leghorn chickens. Inoculated by the intra air sac route with a relatively low dose (5ELD50) of avian strains, the chickens showed generalized infection within 10 days after inoculation followed by death. Horizontal transmission from chickens that received avian strains to their cage mate chickens was demonstrated by the recovery of C. psittaci in the organs. Chickens inoculated with an avian strain shed infectious organisms in the feces at high doses (100.8-≥103.5ELD50). Whereas in the chickens inoculated with mammalian strains, shedding of chlamydia was very limited. The mammalian strains were far less pathogenic to 8-day-old chickens than avian strains. In the chickens that received low doses of either avian or mammalian strains, high immunofluorescent antibody response was observed 2 to 3 weeks after inoculation.
