Improved contact tracing of Chlamydia trachomatis in a Swedish county--is genotyping worthwhile?

The vast majority of genital Chlamydia trachomatis infections are non-symptomatic or mildly symptomatic. Efficient contact tracing and screening programmes are the most effective means to reveal these infections. We conducted a prospective study on the effects of contact tracing performed by specially trained midwives in a centralized municipality-based organization during one year. In order to improve the efficiency of the contact tracing, all C. trachomatis-positive isolates in the county during one year were typed by sequencing the ompA gene. Contact tracing in two municipalities the year prior to the study revealed 1.6 partners for each index case (n = 110). The corresponding figure for the whole county during the study period was 2.1 partners per index case (n = 2065). Genotyping added valuable information in mapping individual sexual networks, but was not essential for achieving satisfactory contact tracing results.