Determinants of trachoma endemicity using Chlamydia trachomatis ompA DNA sequencing

A six-year prospective study of Chlamydia trachomdtis infection and ocular disease in Tanzanian village children was conducted to identify the determi nants of trachoma endemicity using sequencing of ompA. Overall, 749 conjunc tival samples were obtained, with 176 children sampled in both 1989 and 199 5. 31.1% (233/749) were positive by PCR-enzyme immunoassay, and 76% (176/ 2 33) of the positives were sequenced in variable domains (VD) 1 to 4 (22 chi ldren in both 1989 and 1995). Twenty-six ompA genotypes of serovar A, and w 19 of B/Ba were identified, and only 20% of genotypes identified in 1995 ma tched those found in 1983. Tn particular, B/Ba genotypes exhibited a 15-bas e region in VD 2 with increased nucleotide substitution, and these types we re associated with age load did predict subsequent severe trachoma (odds ra tio (OR) = 10.14, 95% confidence interval (CI): 1.71, 60.23; OR = 6.40, 95% CI: 0.75, 54.41; OR = 6.74, 95% CI: 0.82, 55.38, respectively). And, multi typic infection was clustered with residence of village and associated with familial cattle ownership. In conclusion, high ompA polymorphism and the i nability of some hosts to clear infection with the same ompA genotype sugge st two distinct but converging mechanisms of endemic severe trachoma. (C) 2 001 Editions scientifiques et medicales Elsevier SAS.