No 35a - 2011

Syphilis 2010

Newly acquired syphilis, i.e. primary and secondary syphilis, is mandatorily notifiable to the Department of Epidemiology, SSI, on Form 1510. Serological verification is performed by the Microbiological Diagnostics Department, SSI. In 2010, a total of 377 cases were diagnosed with newly acquired syphilis. Consequently, the number of syphilis cases has increased further since 2009, Figure 1. The diagnosed cases distributed by age group and sex are shown in Table 1.

Syphilis cases - diagnostics
Among the diagnosed cases, a total of 362 (97%) were notified to the Department of Epidemiology; 342 (94%) were diagnosed by serology and 18 (5%) by PCR testing of specimens from chankers. In two (1%) cases, no information about diagnostic method was available. Overall, 15 laboratory confirmed syphilis cases were not notified: two cases diagnosed by PCR and 13 diagnosed by serology.

Congenital syphilis
Two cases of congenital syphilis were notified in 2010. One of the two children’s mothers was a foreigner who had only recently arrived in Denmark. The other child's mother was Danish, she had become pregnant before general screening was introduced, EPI-NEWS 27-33/10.

Demography of notified cases
The 362 cases comprised 329 male cases and 33 female cases including five who were detected at pregnancy screening. The median age was 35 years (0-72 years) for males and 31 years (16-69 years) for females. Among males, a total of 288 (88%) were Danish-born, 40 (12%) were immigrants and one was a tourist. Among females, a total of 25 (76%) were Danish-born, six were immigrants and two were tourists. Among males, 272 (83%) cases occurred in men who have sex with men (MSM). Table 2 presents the distribution by area. As in previous years, a considerable number of cases were observed in Copenhagen City.

Country of infection
The country of infection was confirmed in 326 (90%) of the notified cases. The majority of these (94%) were infected in Denmark. Among heterosexually infected males, 35 (80%) were infected in Denmark, while this was the case for 26 (96%) of MSM. Among females, 26 (96%) were infected in Denmark.

Syphilis and HIV
Information on HIV status was available in 308 males (94% of MSM and 94% of heterosexually infected males) and in 26 (79%) females. Among HIV tested males, a total of 108 (35%) were HIV positive. Among MSM, a total of 104 (40%) were HIV positive, and among heterosexually infected males, four (9%) were HIV positive. One female was HIV positive. A total of 55 (17%) males and two (6%) females had previously been notified with syphilis. All 55 previously notified males were MSM and 35 (64%) of these were HIV positives. A total of sixteen (29%) of the 55 males who had several syphilis notifications, had been notified more than twice, and among these, fourteen (88%) were HIV positive. Among the females, one of the two previously notified cases was HIV positive.

Commentary
In 2010, congenital syphilis was diagnosed in Denmark for the first time since 2003. The affected cases were two children whose mothers were not comprised by the general screening of pregnant women reintroduced at the beginning of 2010. Congenital syphilis may cause serious sequelae. As the condition does not always present at birth, it is important to be aware of the diagnosis if the mother has not participated in the general screening. Late-stage congenital syphilis may manifest as damage to bones, teeth, eyes, ears and the central nervous system. Syphilis is still more prevalent in MSM and the increase in this group continues, EPI-NEWS 35/10.

However, syphilis is no longer entirely rare among heterosexuals, as  demonstrated by the general syphilis screening in pregnant women, EPI-NEWS 15/11. In 2010, seven females were diagnosed with syphilis in the pregnancy screening, including two who were not notified until 2011. In 2010, pregnant females thus comprised 15% of notified female cases. Syphilis is a marker of unprotected sex and therefore also a marker for risk of HIV infection. As more than half of the syphilis cases in MSM occur in HIV negatives, it remains important that patients tested for syphilis also undergo a HIV test, EPI-NEWS 46/09. Furthermore, MSM should regularly undergo syphilis testing. Additionally, it is important to keep in mind the diagnosis of other sexually transmitted diseases, e.g. gonorrhoea and lymphogranuloma venereum (LGV).

(B. Søborg, S. Cowan, Dept. of Epidemiology, S. Hoffmann, J.S. Jensen, DBMP)

31 August 2011