1 National Institute of Public Health and the Environment
(RIVM), Bilthoven, the Netherlands
2 Municipal Health Service, (GGD Rotterdam e.o.) Rotterdam, the Netherlands
3 STI clinic, Erasmus Medical Centre, (Erasmus Medisch Centrum), Rotterdam,
the Netherlands
Following earlier recognition of a syphilis outbreak in
Rotterdam (1), the outpatients’ clinic for sexually transmitted infections
(STIs) of the Erasmus Medisch Centrum Rotterdam (Erasmus Medical Centre Rotterdam)
has diagnosed 56 cases of infectious syphilis (including primary, secondary,
early latent) in 2002, compared with 24 cases in 2001 and 16 in 2000. (Figure
1). Between January and April 2003, 15 cases of infectious syphilis were seen
at the Rotterdam STI clinic (6 primary, 5 secondary, 4 early latent) compared
with 10 in the same period in 2002. In 2002, 15 cases were in heterosexuals
(11 men and 4 women) and 41 cases were in men who had sex with men (MSM) (14
primary, 9 secondary, 18 early latent).
Figure 1: Number of cases of infectious syphilis by stage
of infection, STI clinic Erasmus Medisch Centrum Rotterdam.
In the past two years the rise in syphilis cases was more apparent in
MSM (Figure 2). Of the 56 patients, 6 had a co-infection with HIV. Of the
41 MSM, 9 had had sex with both men and women, and 32 with men only. Thirty
four of the MSM reported anal sexual contact in the past 6 months. Information
on condom use and oral sex was not available. All the patients co-infected
with HIV were MSM: 4 were known HIV positive patients and 2 were newly diagnosed.
In the anonymous unlinked HIV surveillance at the STI clinic, 4 HIV infected
individuals who were co-infected with syphilis were seen. In 2001, 5 syphilis
patients were co-infected with HIV (4 known and 1 newly diagnosed). The
percentage of co-infection of syphilis and HIV may be an underestimate as
the HIV serostatus was unknown in 51% of the men.
Eight of the 15 heterosexuals (53%) reported their ethnicity or country
of origin as being from Surinam and the Dutch Antilles, 2 reported their
country of origin as the Netherlands (13%) and 5 reported that they were
from elsewhere (33%). Information on the source of infection was not available.
Two women with infectious syphilis were commercial sex workers (CSW). Three
of the 11 heterosexual men were clients of CSWs.
Figure 2: Number of cases of infectious syphilis by gender
and sexual orientation, STI clinic Erasmus Medisch Centrum Rotterdam (Note:
sexual orientation was unknown for the majority of cases in 2000)
Enhanced surveillance
After the outbreak of syphilis among CSWs in 1995-97 in Rotterdam
(2), there were no signs of increased transmission of syphilis in the city,
despite reports of increasing rates of syphilis and gonorrhoea at the Amsterdam
STI clinic (1, 3). In the second half of 2001 the number of syphilis cases
started to increase in Rotterdam. From July 2002 onwards, enhanced surveillance
was used to identify risk factors. Between July and December 2002, 33 patients
(32 men and 1 woman) were interviewed by the public health nurse as part
of enhanced surveillance.
Having a regular partner was reported by 20 of the 32 men, two of them
were women. Multiple casual partners were reported by 91% of the patients:
on average 4.3 partners (median was 2, maximum was 30) in the previous 3
months. On average 7.7 (median was 3) partners were reported in the past
6 months. Many partners remained unknown and could therefore not be identified
for contact tracing. Ten of 26 MSM reported only oral contact as the possible
route of transmission, while 16 others had also had anal contact. Condoms
were used in most cases of anal intercourse but almost never in oral contacts.
Five of the syphilis patients knew that they were HIV positive (15%); 15
were HIV negative (45%) and of 13 patients the HIV serostatus was unknown
(40%). Also, 18 patients (55%) reported a prior STI diagnosis. Patients
with syphilis reported a large variety of social venues where they met sexual
partners: 20 of them had met their sex partners in Rotterdam (in gay bars,
saunas, cruising zones), 7 in Amsterdam (in saunas), 7 abroad and 5 had
met through internet chat rooms. This outbreak has led to intensified counselling
on HIV and syphilis. Ongoing outreach prevention has been expanded and focused
on syphilis and risk of HIV transmission with an emphasis on safe sex and
the need for regular testing.
Ongoing transmission in 2003
All of the 15 cases diagnosed between January and April 2003 have been in
men, of which 13 were MSM, and of which 3 were known HIV positive individuals
(2 MSM and 1 heterosexual). These figures suggest that transmission of syphilis
is ongoing in Rotterdam.
Discussion
Similar syphilis outbreaks among MSM have been reported in other cities
throughout Europe; some of which have involved co-infection in known HIV
positive patients (3-15). These outbreaks may have implications for the
incidence of HIV infection as HIV positive MSM who are co-infected with
syphilis may spread HIV infection more easily (16-18). It also implies that
sexual behaviour in MSM may be changing.
The syphilis outbreak in Rotterdam is occurring within a group of high-risk
individuals, with a high rate of partner change, with anonymous partners,
with a relatively high proportion of HIV positive individuals. Oral transmission
was also often reported. It emphasises the need for primary prevention and
risk reduction strategies, as well as continued efforts at active case finding
and partner tracing both for HIV and STI.
Acknowledgements: We thank the counsellor nurses for their work interviewing
the patients at the STI clinic.