RESUMEN
BACKGROUND & OBJECTIVES: Different species of genus Chlamydia have been associated with ocular, genitourinary and respiratory infections, and coronary artery disease. Since the majority of these infections remain asymptomatic or subclinical, antibodies may be present in apparently healthy individuals, and the determination of species specific Chlamydia antibodies in a healthy population may reflect exposure. We therefore screened the sera of healthy blood donors for species specific Chlamydia antibodies by microimmunofluorescence assay. METHODS: Sera of 844 voluntary blood donors from Delhi were screened by microimmunofluorescence assay using specific antigens of C. trachomatis (18 serovars divided in 3 pools of serotypes A-C, D-K and L1-L3), C. psittaci and C. pneumoniae for Chlamydia antibodies. RESULTS: A total of 470 (55.69%) blood donors were found positive for Chlamydia antibodies. Of these, 361(42.77%) were positive for C. pneumoniae, 106 (12.5%) for C. trachomatis [of which 72 (8.5%) were against serotypes D-K and 34(4%) were against serotypes A-C]. There donors (0.3%) had antibodies to C. psittaci. INTERPRETATION & CONCLUSION: The results suggested that more than half of the study population (55.69%) is exposed to one or other species of chlamydiae. Majority of the donors (44.7%) had C. pneumoniae antibodies, suggesting the presence of widespread apparent or inapparent C. pneumoniae infection. The findings also suggest that Chlamydia antibody testing for the diagnosis of chlamydial infections may not be helpful due to the presence of antibodies in a large proportion of healthy individuals.