How many cases of chlamydial infection would we miss by not testing partners for infection?

Quality Improvement Scotland standards for sexual health services require that 0.64 contacts per case should be verified as having attended within 90 days of the first partner notification interview. Partner delivered therapy results in more patients being treated than when patients are given information for partners but removes the possibility of further cases of Chlamydia trachomatis being diagnosed through the tracing of secondary contacts. An audit was performed to estimate the impact of removing secondary contacts on the number of chlamydial infections identified in our service. Patients who were not known to be contacts of chlamydial infection were included. One hundred and twenty-seven index cases generated 189 contacts, of which 100 were confirmed as tested and treated. Sixty-four were C. trachomatis positive, who in turn generated 36 new contacts. Fourteen of these were positive. Secondary contact tracing identified 22-28% more cases of chlamydial infection in our service than if all partners were treated without testing.