Direct-smear fluorescent antibody cytology as a field diagnostic tool for trachoma.

A recently developed direct-smear fluorescent antibody (DFA) cytology method of detecting chlamydial infection was evaluated in an area where trachoma is endemic. Four hundred seventy-five children aged 2 to 10 years were examined, and adequate conjunctival cytology specimens were collected from 457 (96%). Trachomatous inflammatory changes were observed in 114 (25%) of the children. The DFA cytologic technique has a high specificity (100%) but a low sensitivity (8%). It offers a number of advantages over existing laboratory methods for diagnosing trachoma in the field. It is a rapid, simple, and easily transferred test that has a high specificity. Although DFA cytology shares the low sensitivity of other laboratory methods of diagnosing trachoma, we believe its logistical advantages make it the laboratory test of choice.