An outbreak of infectious syphilis in Wellington, New Zealand

To estimate the incidence of infectious syphilis in the Wellington region between 2004 and 2006, and to characterise those with infectious syphilis, in terms of demographic and risk factors, in order to inform control of the disease.

Based on information from regional laboratories, a questionnaire was sent to the requesting clinician for all individuals with positive syphilis serology between January 2004 and December 2005. The questionnaire was also used for cases of infectious syphilis seen at regional sexual health clinics in 2006. All information was recorded anonymously.

120 questionnaires were returned (67%), and 15 cases of infectious syphilis were identified (5 in 2004, 10 in 2005), including 3 cases not known to the sexual health clinics and hence not reported to the Institute of Environmental & Scientific Research (ESR). Another 15 cases of infectious syphilis were identified from sexual health clinic records in 2006 up to October. These 30 cases of infectious syphilis were predominantly men who have sex with men (MSM) (80%), and mainly born in New Zealand (83%). Few cases reported recent sex overseas, indicating local transmission, and anonymous partners were common. The annual incidence (per 100,000 population) of infectious syphilis is estimated at 1.3 in 2004, 2.6 in 2005, and 5.9 in 2006.

Wellington is experiencing an outbreak of infectious syphilis, principally amongst MSM, but with crossover into the heterosexual community. Efforts are being made to control this outbreak through education of clinicians, partner notification, and offering screening and education in non-medical settings to at risk groups. We call on the Ministry of Health to enhance syphilis surveillance as a matter of urgency.