Spread of Agents
Human diseases caused by chlamydiae can be divided into two types: (1) chlamydial agents transmitted by direct contact (C trachomatis genital and ocular infections, C pneumoniae ocular infection) and (2) chlamydial agents that are transmitted by the respiratory route (C psittaci and C pneumoniae.)
The spread of C trachomatis from person to person may cause trachoma, inclusion conjunctivitis, or lymphogranuloma venereum. Transmission of C trachomatis from the urogenital tract to the eyes and vice versa occurs via contaminated fingers, towels, or other fomites and, in neonates, by passage through an infected birth canal. These diseases appear in an epidemic form in populations with low standards of hygiene. Chlamydia trachomatis genital infections are sexually transmitted. Chlamydia psittaci is transmitted from infected birds or animals to humans through the respiratory tract. Chlamydia pneumoniae spreads from infected individuals by respiratory tract infections hut is not sexually transmitted.