Antibodies to two immunotypes of Chlamydia trachomatis in individuals with trachoma.

In Tunisia (North Africa), trachoma remains a common eye disease. Most cases are caused by immunotype A of Chlamydia trachomatis. In a small proportion of cases (less than 10%), type-specific antibodies to both immunotype A and immunotype B exist in the serum of patients. These types do not crossreact, and occasionally sequential acquisition of antibodies has been demonstrated. Thus, individuals in one endemic area of trachoma may be infected with two immunotypes of C. trachomatis. The epidemiological and immunological implications of this new finding are briefly discussed.