(Wang and Grayston, 1970;Treharne et al., 1971) has greatly facilitated the study of the TRIC agents responsible for hyperendemic trachoma of eye-to-eye transmission, and the TRIC agents of paratrachoma (both ocular and genital) of sexual transmission, with occasional transfer to the eye (Jones, 1975;Treharne et al., 1977).The microimmunofluorescence method has also been applied to the measurement of type-specific antichlamydial antibody in serum (Dwyer et al