UC Berkeley

Following the introduction of penicillin in the 1940s, the incidence of infectious syphilis in the United States dramatically declined from a high of 70.9 per 100,000 in 1946 to a historic low of 2.1 in 20001. In the decade since, syphilis has shown signs of re-emergence, with the incidence rate of infectious syphilis in the U.S. increasing to 5.5 per 100,000 in 2013. Infectious syphilis trends in California have largely paralleled those of the rest of the country, but with an incidence rate consistently above the national average. After decades of substantial progress in syphilis control, the incidence of infectious syphilis in California increased from a low of 0.9 per 100,000 (284 cases) in 1999 to 9.3 in 2013 (3,554 cases)2. As in other major metropolitan areas in the U.S., the majority of syphilis cases in California are among men who have sex with men (MSM), with a high proportion reporting HIV co-infection. Syphilis infection can result in major health complications if untreated, and also facilitates the transmission and acquisition of HIV3-5.

In addition to mandated reporting to health departments, syphilis partner services – in particular, partner notification - are a standard public health practice for identifying potentially infectious individuals for testing and treatment, thereby interrupting transmission of syphilis within sexual networks and reducing incidence of the illness in the general population6. However, the increasing incidence of syphilis in California, the frequent reporting by patients with syphilis of anonymous sex partners, and the lack of a clear measure of partner services effectiveness raise questions concerning the impact this intervention is having on spread of disease, and to what extent the data acquired through syphilis partner services provide meaningful information about how the underlying sexual networks contribute to trends in syphilis morbidity in various populations.

The objectives of this dissertation are 1) to review studies evaluating syphilis partner notification efforts and compare outcome definitions and measures of effectiveness, 2) to analyze the structure and characteristics of sexual networks detected through routine syphilis surveillance and partner notification efforts in the San Francisco Bay Area Region, and 3) to make recommendations concerning how public health departments might use syphilis surveillance data to better understand such networks and to provide opportunities for case-finding and disease prevention.

This dissertation will directly inform a common public health intervention by assessing the utility of existing public health data for understanding and preventing transmission of syphilis within networks, and by discussing ways in which resources might be deployed to reduce the incidence of syphilis more effectively.