Incidence of Chlamydia antibody in patient groups, as measured by the ELISA technique.

An ELISA technique has been used to study the incidence of antibody against Chlamydiae: the results obtained with a panel of control sera were compared with those for the complement fixation (CF) and whole inclusion immunofluorescence (WIF) tests. The results indicate that the ELISA results correlate well with the WIF test but poorly with the CF test; and the correlation allows ELISA results to be directly related to WIF antibody titres. Using the ELISA test, the incidence of antibody to Chlamydiae by age was determined in sera collected in Great Britain and Iraq; and in sera collections made at three periods during the last 30 years in Great Britain: the results indicate the higher incidence of antibody in this country compared to Iraq, but do not suggest an increased incidence of antibody in Great Britain during the last 30 years. Studies on sera collected from patients with non-gonococcal urethritis and pelvic inflammatory disease indicate significantly higher titres and incidence of antibody compared to controls, which suggest a contiguous spread of infection for the primary genital lesion to involve more distant tissues and organs. A higher incidence of antibody was also seen in patients with cervical intraepithelial neoplasia (CIN) which may be interpreted as either indicating a causal relationship between Chlamydiae and CIN or indicating the importance of a venereal infection in this condition.