Background: Contact tracing is one of the central pillars of the management of sexually transmitted infections. The aims of this audit were to determine the yield of chlamydia infection from contact tracing the sexual partners of individuals diagnosed with chlamydia and to evaluate and compare the effectiveness of contact tracing undertaken at the Communicable Diseases Control Section (CDCS) of Australian Capital Territory (ACT) Health and the Canberra Sexual Health Centre (the clinic).
Methods: A retrospective review of the notification records and contact-tracing documentation was undertaken at CDCS and the clinic from 1 September 2002 to 30 September 2003 (13 months).
Results: The background rate of chlamydia in those tested in the ACT community is 3-5%. During the study period, 512 cases of chlamydia were notified to CDCS. Of these, 351 were referred for contact tracing, 293 by CDCS and 98 by the clinic. Of the 437 nominated sexual contacts (average of 1.12 per index case), 272 (62.2%) were contacted, 125 (28.6%) were tested and 51 (11.7%; 95% CI 8.8-15.1) tested positive for chlamydia (15.5%; 95% CI 11.5-20.6% in sexual contacts of CDCS index cases and 7.8%; 95% CI 4.8-12.5% in those of the clinic patients). Contact tracing through the CDCS reached significantly more nominated sexual contacts (78.4% v. 41.7%; P = 0.001) and significantly more of the nominated sexual contacts of index cases reported to CDCS were described as tested (34.7% v. 20.8%; P = 0.01). The average time taken to identify each chlamydia-positive sexual contact was 6.8 hours.
Conclusions: Contact tracing more than doubled the case finding effectiveness of chlamydia screening, but was time consuming. These results suggest that provider-initiated contact tracing has clinical and public health value, but that the cost-effectiveness of this approach to chlamydia control should be further evaluated.