A van den Hoek

STD control in drug users and street youth.

OBJECTIVE: To review the relation between drug use, sexual risk behaviour, and STDs including HIV in two marginalised populations--drug users and street youth. METHODS: A review of recent medical and behavioural literature focusing on illustrative examples from industrialised countries. FINDINGS: Injecting and other illicit drug users and street youth are both sexually active populations with a high rate of partner turnover and frequently exchange sex for money or drugs. Both STDs and HIV are prevalent among injecting and crack using individuals. Drug use may lead drug users to be less aware of or concerned about STD symptoms than others with STDs and thus increase the threshold for attending clinical services. CONCLUSIONS: Given that STDs facilitate the transmission of HIV and that standard STD control programmes in general do not reach these populations, it is argued that drug users and street youth require targeted special outreach STD control programmes.

Genotyping of Chlamydia trachomatis serovars derived from heterosexual partners and a detailed genomic analysis of serovar F.

OBJECTIVE--To investigate C trachomatis serovars in contact-traced heterosexual partners. METHODS--Urogenital Chlamydia trachomatis isolates (n = 112) derived from 35 heterosexual patients (index patients) and their 37 chlamydia positive partners (contact patients) were differentiated into serovars by genotyping with restriction fragment length polymorphism (RFLP) analysis of the PCR amplified omp1 gene. In order to investigate whether different strains within the frequently prevalent serovar F were transmitted, two pairs of serovar F (n = 4) were further analysed by genomic DNA fingerprinting with arbitrary primer PCRs (AP-PCRs). RESULTS--Identical C trachomatis serovars were found in 31 of the 35 pairs, serovars E, F, D, and G being most prevalent. In the remaining four pairs different serovars (either D, E, F or G) were found between the index and the contact patients. By AP-PCR analysis the strains of serovar F were found to be identical between the index and the contact patients, but were different between the two pairs in all AP-PCRs used. CONCLUSION--A majority of heterosexual partners, once traced positive for C trachomatis infections, are infected with identical serovars. Identical strains of serovar F found in partners as found by DNA fingerprinting confirms the sexual transmission of C trachomatis.

P3.420 Targeted Vaccination Programme Successful in Reducing Acute Hepatitis B in Men Having Sex with Men in Amsterdam, the Netherlands

Background In the Netherlands, transmission of hepatitis B virus occurs mainly within behavioural high-risk groups, such as in men who have sex with men. Therefore, a vaccination programme has targeted these high-risk groups. Previous evaluations of this programme up until 2006 (incidence trend analysis, mathematical modelling and molecular sequence models) could prove no impact. This study evaluates the impact of the vaccination programme targeting Amsterdam’s large population of men who have sex with men from 1998 through 2011. Methods We used Amsterdam data from the national database of the vaccination programme for high-risk groups (January 1, 1998 to December 31, 2011). Programme and vaccination coverage were estimated with population statistics. Incidence of acute hepatitis B was analysed with notification data from the Amsterdam Public Health Service (1992 to 2011). Mathematical modelling accounting for vaccination data and trends in sexual risk behaviour was used to explore the impact of the programme. Results At the end of 2011, programme coverage was estimated at 41% and vaccination coverage 30% to 38%. Most participants (67%) were recruited from the outpatient department for sexually transmitted infections and outreach locations such as saunas and gay bars. Incidence of acute hepatitis B dropped sharply after 2005. The mathematical model in which those who engage most in high-risk sex are vaccinated, best explained the decline in incidence. Conclusions Transmission of hepatitis B virus among Amsterdam’s men who have sex with men has decreased, despite ongoing high-risk sexual behaviour. International concern also exists about the effectiveness of such programmes when the uptake or coverage remains low. This study proves that a targeted vaccination programme can be effective with vaccination coverage below 40%, as long as MSM who engage most in high-risk sex, such as clients of STI clinics, are reached.

P4.088 Unprotected Casual Sexual Contact Common with Both Local and Western Partners Among Dutch Long-Term Travellers to (Sub)Tropical Countries

Background Casual sex among travellers is common. It is unknown whether travellers use condoms differently with local versus western casual partners when visiting HIV endemic areas. We determined the number of casual sexual partners and consistency of condom use among Dutch long-term, non-expatriate travellers to (sub)tropical regions according to the ethnicity of their casual sexual partners, and estimated the incidence of HIV and syphilis on their return. Methods A prospective mono-centre study of Dutch long-term travellers ≥ 18 years, attending the Public Health Service travel clinic in Amsterdam (2008–2011) and travelling to any (sub)tropical country for ≥ 12 and ≤ 52 weeks, was conducted. Travelers reported their travel purpose, duration, destinations(s), number and nature of sexual contacts while travelling: ethnicity, gender, partner type (steady/casual) and consistency of condom use with each partner. Analyses were conducted using Poisson regression (generalised estimating equations to account for multiple partnerships). Blood samples, taken before and after travel, were tested for HIV and Treponema-pallidum antibodies. Results There were 552 respondents and 11671 person-weeks of follow up (median age:25 years, 36% male, median travel time:20 weeks, 45% for work/study). Post travel, 34%(n = 190/552) reported ≥ 1 casual sexual partner, men a median of 3 (range:1–8) and women 2 (range:1–7) partners. Of 462 casual sexual partnerships, 42%(n = 192) were with local partners at travel destination. Equally, 39% of partnerships with western and local partners were unprotected. Single travellers (IRRsteady partner(ref):2.2.95% CI: 1.2–4.0) and those on holiday (IRRwork/study (ref):1.9.95% CI: 1.2–3.0) had more unprotected casual sex. Partner’s ethnicity was not significant in predicting condom use. No HIV or syphilis seroconversions were recorded. Conclusion Unprotected casual sex was common among Dutch long-term travellers, occasionally with multiple local partners in HIV-endemic regions. Single travellers and those travelling for holiday purposes were most at risk. These groups should be advised on the need for safe sex while abroad.

P2-S4.07 Unsafe casual travel sex with discordant and concordant partners is common among visitors of a large STI outpatient clinic in Amsterdam; risk for international spread of STI

Background Travelling has always been an important factor in the spread of STI. In the last decades international travelling has become very popular and therefore the risk for spreading STI internationally has become higher. Here we examine determinants of casual travel sex among visitors of a large STI clinic in the Netherlands. With these results specific advice about safe casual travel sex might be given. Methods During three waves of the bi-annual anonymous survey (mid 2008–mid 2009), 2971 attendees of the STI clinic Amsterdam, were interviewed about risk factors for blood-borne and sexually transmitted infections and about casual travel sex in the past 6 months. Determinants of casual travel sex were analysed using logistic regression. Analyses were done combined and separately for participants with Western, Surinam, and other ethnicity. Results In total 949/2971 (32%) participants had casual travel sex in the 6 months preceding the visit to our STI clinic. Of these participants 265 (28%) were women, 299 (32%) heterosexual men and 385 (41%) MSM. Participants who had casual travel sex were more often heterosexual men (OR 1.66, 95% CI 1.37 to 2.01) or MSM (OR 3.03, 95% CI 2.50 to 3.68), were older (median 31 vs 27; p<0.0001), had more often a history of STI (OR 1.66, 95% CI 1.42 to 1.94) and had a higher number of life time sexual partners (median 26 vs 13; p<0.0001). Participants who had unsafe travel sex were younger (mean 29 vs 33; p<0.001) and had less often a STI in the past (OR 1.41, 95% CI 1.08 to 1.82). In particular Western participants reported a high number of casual travel sex with discordant ethnic partners. In addition they reported more frequently unsafe sex with both discordant and concordant ethnic partners (see table). Around 60% of Western women, heterosexual men and MSM who had casual travel sex, had sex with a discordant ethnic partner. However, Western MSM were more likely to use a condom during casual travel sex (OR 2.39, 95% CI 1.45 to 3.92) than heterosexual men and women see Abstract P2-S4.07 Table 1. Abstract P2-S4.07 Table 1 Number of participants who have casual travel sex per ethnicity group Casual travel sex With discordant ethnicity group Unsafe sex with discordant ethnicity group Unsafe sex with concordant ethnicity group Participant  Western * 647/1931 (33.5%) 384/647 (59.0%) 201/380 (52.9%)† 160/263(60.8%)  Suriname 70/358 (19.6%) 35/70 (50.0%) 13/35 (37.1%) 18/34 (52.9%)†  Other 232/682 (34.0%) 93/232 (40.1%) 48/93 (51.6%) 73/136 (53.7%)† * Dutch included. † Missings excluded. Conclusion Casual travel sex is very common among visitors of our STI clinic compared with the ca. 5% reported among visitors of a travel clinic, in particular among visitors who are older, with a high number of lifetime sex partners and with previous STI. These findings give insight in the risk of the international spread of STI and may be of help in providing specific pre-travel advice on safe sex abroad.

O1-S10.01 High HIV incidence among MSM who were prescribed HIV-PEP: indications for further riskful sexual behaviour

Background Are MSM who were prescribed PEP, men with high risk behaviour or men who incidentally had a riskful sexual contact? One way to answer this question is to compare the HIV incidence among MSM who were prescribed PEP with the HIV incidence among MSM without such request, using HIV incidence as a surrogate marker for highly riskful sexual behaviour. Methods The HIV-PEP cohort consisted of MSM who were prescribed a 28 day PEP-course after a riskful sexual contact between 2000 and 2009 in Amsterdam, the Netherlands, who were HIV negative at baseline and had a follow-up HIV test at 3 and 6 months. Predictors for seroconversion were analysed using χ2 tests and Mann–Whitney U tests. The comparison cohort consisted of MSM participating in the Amsterdam Cohort Studies (ACS) who were tested every 6 months in the same study period. The latter cohort aims to represent the overall gay community in Amsterdam. HIV incidences, including 95% CIs, were calculated for both cohorts by dividing newly diagnosed HIV-infections by total Person Years (PY) under observation. Results The HIV-PEP cohort comprised of 395 PEP prescriptions (n=321 MSM with one PEP prescription; n=34 MSM with two or more PEP prescriptions) with a total follow up time of 169.45 PY. The median age at PEP prescription was 35 (IQR 30-41) and 62 % was born in the Netherlands. In 61% of the cases PEP was prescribed for receptive unprotected anal intercourse (RUAI) and MSM who seroconverted were more likely to report RUAI compared to those who did not seroconvert (82% and 60% resp.; p=0.15). In the ACS cohort 809 MSM participated with a total follow-up time of 4412 PY. The median age at visit in the ACS was 32 (IQR 28-36) and 86% was born in the Netherlands. The HIV incidence in the time period 2005–2009, as well as the overall HIV incidence in the total study period, was four times higher in the HIV-PEP cohort compared to the ACS (Abstract O1-S10.01 table 1). In the HIV-PEP cohort the overall HIV incidence was 6.49 (95% CI 3.24% to 11.62%) per 100 PY, compared to 1.59 (95 % CI 1.25% to 2.0% per 100 PY in the MSM in the ACS in the same study period (p<0.001). Abstract O1-S10.01 Table 1 HIV incidences among MSM of the HIV-PEP cohort and of the Amsterdam Cohort Studies (ACS), 2000–2009 HIV-PEP cohort ACS Time period No. of serocon-versions Person Years (PY) under observation Incidence density per 100 PY (95% CI) No. of serocon-versions Person Years (PY) under observation Incidence density per 100 PY (95% CI) p Value 2000–2004 1 42.1 2.38 (0.12 to 11.73) 26 2095 1.24 (0.83 to 1.79) NS 2005–2009 10 127.4 7.85 (4.0 to 14.0) 44 2317 1.90 (1.40 to 2.53) <0.001 Total study period 2000–2009 11 169.5 6.49 (3.4 to 11.3) 70 4412 1.59 (1.25 to 2.0) <0.001 NS: Not Significant. Conclusions The HIV incidence of MSM who were prescribed a PEP course was four times higher than in the overall gay community in Amsterdam. Our results show that PEP users belong to a group of MSM at high risk for HIV infection. Further analyses will be conducted to compare predictors of HIV seroconversion in both cohorts.

Outbreak of legionnaires disease in Amsterdam, June-July 2006.

An outbreak of legionnaires’ disease is occurring in Amsterdam, where 23 cases confirmed by urinary antigen test were reported between 6 and 13 July 2006, and one patient has died