Syphilis 2019 and 2020

Syphilis 2019 and 2020

The present report on notified syphilis cases in 2019 and 2020 only comprises data from the Notification System for Infectious Diseases (NSID) and from the Syphilis Laboratory at Statens Serum Institut (SSI).

In 2019, 365 syphilis cases were notified to the NSID, Department of Infectious Disease Epidemiology and Prevention (DIDEP), SSI. The 365 cases occurred in 353 persons as 12 persons had two cases notified in the course of the year.

In 2020, the figure was 446 cases occurring in 435 persons, as 11 persons had two cases notified in the course of the year.

For men, the median age notified in 2019 was 40 years (range 0-74 years); for women, 32 years (range 17-73 years), Table 1.

For men, the median age notified in 2020 was 40 years (range 19-76 years); for women, 34 years (range 18-57 years), Table 1.

As in previous years, the majority of the patients resided in the Copenhagen area, Table 2.

The decline registered in 2018 when the number of notified syphilis cases was 311 has now been replaced by an increase, Figure 1. Even before all syphilis notifications for 2021 have been received, it is already now clear that this increase will continue. The increase is observed only among men who have sex with men (MSM).

Congenital syphilis and syphilis in pregnant women

Among 39 cases of syphilis detected in women in 2019, seven (18%) were found in pregnant women, of whom five were born in Denmark. In 2020, a total of 37 women were notified, whereof nine (24%) were pregnant - five of whom were born in Denmark.

A single case of congenital syphilis was notified in 2019. The mother had syphilis detected in connection with the pregnancy screening.

Transmission

Sexual orientation

2019: Among the 326 notified men, 57 (17%) were notified as having become infected by heterosexual contact (HTX), 251 (77%) by MSM contact, and for 17 (5%) the mode of infection was not stated. Furthermore, one patient was notified as having become infected by mother-to-child-transmission. A total of 39 women were notified, all due to HTX transmission (11% of those notified), Figure 1.

2020: Among the 409 notified men, 78 (19%) were notified as HTX infections, 319 (78%) as MSM infections, and for 12 (3%) the mode of infection was not stated. A total of 37 women were notified - 36 hereof were notified as HTX infections (8% of all notified) - and one woman was notified as a woman who has sex with women, i.e. homosexual infection, Figure 1.

Origin and country of infection

2019: Among the 365 cases in which origin was stated, 253 (69%) were of Danish origin, 94 (26%) were immigrants, 11 (3%) were second-generation immigrants and seven (2%) were either tourists or illegal immigrants.

The country of transmission was stated for 314 (86%) of those notified, 277 men and 37 women. A total of 234 men (84%) and 30 women (81%) had become infected in Denmark. Among heterosexually infected men for whom the country of transmission was stated, 38 of 52 (73%) had become infected in Denmark, while this was the case for 191 of 217 (88%) of the MSM.

Among MSM notified as having become infected abroad, Spain was the most frequent country of transmission, whereas Thailand was the most frequent country of transmission for men notified with HTX transmission abroad.

2020: Among the 444 cases in which origin was stated, 294 (66%) were of Danish origin, 138 (31%) were immigrants, nine (2%) were second-generation immigrants and three (1%) were either tourists or illegal immigrants.

The country of transmission was stated for 398 (89%) of those notified, 366 men and 32 women. A total of 336 (92%) men and 30 women (94%) had become infected in Denmark. Among HTX-infected men for whom the country of transmission was stated, 60 of 73 (82%) had become infected in Denmark, while this was the case for 267 of 284 (94%) of the MSM.

To ensure patient anonymity, the exact figures for HTX and MSM infectees abroad are not provided on a country-by-country basis.

Syphilis and HIV

2019: Information about HIV status was available for 306 (94%) men and 35 women (90%).

Among the HIV-tested men, 69 (23%) were HIV positives. A total of 68 HIV-positive men were found among 239 MSM (28%) and one (2%) among 53 men notified as HTX infected. Among the 69 HIV-positive men, nine (13%) received their HIV diagnosis concurrently with their syphilis diagnosis; all nine of these cases were MSM. No women were reported as being HIV positives.

2020: Information about HIV status was available for 377 (92%) men and 31 women (84%).

Among the HIV-tested men, 80 (21%) were HIV positives. A total of 76 HIV-positive men were found among 319 MSM (24%) and four (5%) among 78 men notified as HTX infected. Among the 80 HIV-positive men, five (6%) received their HIV diagnosis concurrently with their syphilis diagnosis; four of these cases were MSM and one case was HTX infected. No women were reported as being HIV positives.

This report is described in EPI-NEWS 1-6/2022.
9 February 2022