Ocular chlamydial zoonosis: an experimental study in monkeys

Two locally isolated strains of Chlamydia psittaci from faeces of apparently healthy sheep and conjunctiva of Holstein heifers suffering from conjunctivitis and pneumonia were used for ocular experimental studies in 7 Rhesus monkeys. Titrated (ELD50 10(3.6)/0.2 ml and 10(4.5)/0.2 ml) partially purified yolk sac suspension of each strain was instilled onto conjunctiva of each animal. The clinical and laboratory studies were followed till 8 weeks post-infection. Both the strains produced trachoma like follicles (0.3-0.5 mm dia) preferably on lower conjunctiva between 2-4 weeks of post-infection. Pannus was not observed in any of the experimental eye. Laboratory studies revealed a good correlation between reisolation, fluorescent antibody test and cytology between 2-4 weeks of post-infection. Highest complement fixing antibody titre 1:32 was recorded in 4 out of 7 animals. The studies indicated that both the animal strains had no barrier across ocular tissues in monkeys, vis-à-vis human conjunctiva.