Antichlamydial antibody in tears and sera, and serotypes of Chlamydia trachomatis isolated from schoolchildren in Southern Tunisia.

A predominance of TRIC serotype A has been isolated from schoolchildren in a population in Southern Tunisia with severe hyperendemic trachoma. The serotyping results correspond precisely with the serological findings in patients' tears and sera. Geometric mean titres of serum or tear antibody in defined populations or areas can thus give a useful indication of the prevalent serotypes. Collection of tear fluids on sponges is a more practical method than collection by filter paper strips and gives higher levels of antibody. The presence of antibody to Chlamydia trachomatis in tears correlates well with the presence of infectious agent in the eye and with the intensity of conjunctival inflammatory disease. The measurement of antichlamydial tear antibody can thus provide a meaningful index of the prevalence and intensity of active trachoma in a population. The role these antibodies may play in resistance to re-infection is not yet clear.