bluuebunny/crossref_metadata_2025 huggingface dataset:
P1-S4.24 Balancing the “supply and demand” of sex acts: implications for modelling the HIV epidemic among men who have sex with men in Southern India
Authors: Mitchell K , Foss A , Prudden H , Williams J , Johnson H , Pickles M , Phillips A , Ramesh B , Washington R , Vickerman P
Published: July 2011

Background

In India, men who have sex with men (MSM) have distinct identities related to the role taken in anal sex (Panthi/Bisexual (PB): mostly insertive, Kothi/Hijra (KH): mostly receptive, Double Deckers: both). Wide discrepancies are found between the supply and demand for sex acts estimated for each group using data on reported frequency of anal sex, role taken and estimated group population sizes.

Methods

Two methods for balancing the number and type of sex acts between different groups were compared. They were used in a deterministic HIV transmission model to estimate mixing patterns and HIV prevalence over the first 20 years of the epidemic (including reported condom use trends) and a subsequent 10-year intervention (10% absolute increase in condom use). Data collected from Bangalore for the evaluation of Avahan (the India AIDS initiative) on the mean reported frequency of sex acts per individual, role taken in anal sex and population sizes for each group were used to construct a mixing matrix. In method A, the PB group size was set to balance the total number of insertive and receptive acts, and receptive acts for each group were distributed among the three groups in proportion to the number of insertive acts offered. In method B, the proportion of receptive acts KH had with other KH was an additional input parameter, with remaining receptive acts distributed as in method A. The number and type of contacts for all groups were adjusted to achieve balancing. The model was run using 300 000 randomly sampled parameter sets drawn from the data and multiple fits were found to group-specific HIV prevalence data.

Results

Model fits for method B had more assortative (like-with-like) mixing than method A, particularly for PB (median number of acts PB have with other PB: 48.5% (IQR 33.3–63.3%) in A, 63.3% (IQR 47.3–74.1%) in B), related to larger PB group sizes and PB taking the insertive role less often in B. Despite these differences, the fitted epidemic curves were very similar for all three groups across the two methods (Absrtact P1-S4.24 figure 1), as was the predicted intervention impact (relative reduction in MSM HIV prevalence after 10 years: A: 18.2% (95% CI 11.0 to 29.2%), B: 18.1% (10.6 to 29.7%)).

Conclusions

The choice of method used to balance insertive and receptive contacts in an HIV transmission model affected the estimates for the amount of like-with-like mixing within different MSM groups, but the estimated impact of an intervention was robust to the method used.

Abstract P1-S4.24 Figure 1

MSM.
P1-S4.25 Using mathematical models to understand the causes of the ecological association seen between HIV and HSV-2 in female sex workers in Southern India
Authors: Mitchell K , Vickerman P , Pickles M , Kaushik M , Verma S , Isac S , Adhikary R , Mainkar M , Alary M , Boily M C
Published: July 2011

Background

Cross-sectional surveys of female sex workers (FSW) in multiple districts in Southern India show a strong ecological association between HIV and HSV-2 prevalence. Modelling was used to determine if this association is primarily due to shared behavioural risk factors (such as partner change rate) or if biological interactions between the two viruses also play a major role.

Methods

Linear regression was used to find significant predictors of FSW HIV prevalence in 17 districts in Southern India (using data from Avahan, the India AIDS Initiative). Explanatory variables investigated included prevalence of different STIs in FSW and clients, mean duration of being an FSW or client, and mean reported number of clients per FSW or FSW visited per client. A deterministic HIV/HSV-2 transmission model without behavioural heterogeneity or transmission co-factors was parameterised using district-specific FSW and client behavioural data and fitted to HIV and HSV-2 prevalence data for each district by varying the per partnership HIV and HSV-2 transmission probabilities. The model was firstly fit to all districts simultaneously assuming a constant HIV and HSV-2 transmission probability to see whether district-level variations in behaviour were sufficient to explain the trends seen, and then fit separately for each district to test for trends in the estimated transmission parameters in different settings.

Results

FSW HSV-2, syphilis, gonorrhoea and chlamydia prevalence, client HIV prevalence and mean number of clients per FSW per week were all correlated with FSW HIV prevalence, but only FSW HSV-2 prevalence remained a significant predictor in multivariate analysis. The dynamic model reproduced the HIV/HSV-2 association when simultaneously fit to all districts, but was a poor fit to data (Abstract P1-S4.25 figure 1). When individual transmission probabilities were fit for each district positive correlations were seen between the HSV-2 transmission probability and both the HIV transmission probability and HSV-2 prevalence, but not between the HIV transmission probability and HSV-2 prevalence or vice versa.

Abstract P1-S4.25 Figure 1

FSW.

Conclusion

These results suggest that differences in mean reported partner change rate or duration of commercial sex are not sufficient to explain the association between HIV and HSV-2 prevalence in FSW in Southern India. However, initial analyses do not show clear evidence for a biological interaction. More detailed models will be used to further investigate the association.
P1-S4.28 Survey of methodology used for the identification and antimicrobial susceptibility testing ofNeisseria gonorrhoeaein Latin America and the Caribbean
Authors: Starnino S , Liao M , Ruben M , Storey A , Dillon J A R ,   GASP-LAC Network
Published: July 2011

Background

The Gonococcal Antimicrobial Susceptibility Surveillance Program in Latin America and the Caribbean (GASP-LAC) in the 1990s had significant impact in identifying trends in antimicrobial susceptibility in the region. To revitalise the GASP-LAC, a survey was undertaken to determine the level of surveillance activity and the methods used for the identification and antimicrobial susceptibility testing (AST) ofNeisseria gonorrhoeae(Ng) isolates.

Methods

A structured questionnaire was distributed to potential participants to collect information regarding surveillance activities and methods used for identification and AST of Ng in LAC countries. Information was also obtained from presentations at the Workshop of the GASP-LAC in November 2010 in Buenos Aires, Argentina.

Results

7 countries completed the questionnaire and four provided unstructured answers regarding the methodologies. All 11 countries were interested in continuing to participate in the GASP-LAC. Of nine countries reporting, seven had an on-going country-wide network for gonococcal AST and two countries collected isolates locally, the number of isolates tested each year varied (25–400). Thayer Martin medium was used for Ng primary culture by all countries answering this question (n=8); among them, four countries used biochemical tests alone, or coupled with Gram stain (n=3) and one country, in addition to the two methods, used antigen detection and the nucleic acid amplification method. Chromogenic cephalosporin was used by all respondents (n=9) for detecting ß-lactamase production. Methods used for AST included agar dilution in 6 of 9 reporting countries, coupled with disc diffusion (n=4) and Etest (n=2); the remaining used disc diffusion alone (n=1) or coupled with Etest (n=2). CLSI interpretation criteria were used in all responding participants (n=9). Ng reference strains included ATCC49226 (n=6), coupled with WHO III, V, VII (n=2) or WHO A-E (n=1).

Conclusions

Different levels of surveillance were noted between countries probably due to various resource availabilities. On the basis of these responses the GASP-LAC Co-ordinating Centre will re-establish and consolidate the GASP-LAC.
P1-S4.30 Point-of-Care HIV Testing with OraQuick Advance HIV-1/2 antibody assay: a systematic review of cost outcomes
Authors: Balram B , Johri M , Ako-Arrey D , Lambert G , Claessens C , Klein M , Cajas J M , Peeling R , Pai N Pant
Published: July 2011

Background

Recently Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group called for a shift from diagnostic accuracy to emphasis on patient-centred outcomes for making policy recommendations. While meta-analyses have evaluated diagnostic accuracy of POC HIV tests, a systematic appraisal of other implementation research outcomes, such as cost, is lacking. Within this context, we reviewed global evidence on cost outcomes of OraQuick Advance HIV—1/2 Antibody Test.

Method

We systematically searched six electronic databases for the period of January 1999 to January 2011. Cost outcomes with OraQuick tests were reviewed and data extracted. For economic evaluation we accepted both partial and full study designs. Outcomes were synthesised into a narrative review.

Results

We identified nine studies offering economic evaluations of oral and blood based OraQuick, of which six were full economic evaluations and remaining were partial evaluations. The full economic evaluations included five Cost Effectiveness Analysis (CEA) and one Cost Utility Analysis (CUA) design; one partial evaluation was a cost comparison study and two were cost analysis studies. All studies were in the USA except one, which was from Mexico. All studies performed sensitivity analyses to explore the impact of uncertainty in their model parameters and findings. Methodological approaches applied by the authors were not standardised and program cost varied by location, but overall there was uniformity in the study conclusions. The studies concluded that OraQuick was cost effective in low prevalence settings and resulted in low rates of false positives which have favourable economic implications. The tests were found to be cost saving to the medical system, and offer the advantage of convenience in administration when compared to current standards of care. Since it was recognised that pre- and post-test counselling cost and personnel costs accounted for most of the overall costs for these rapid tests, one approach that was proposed to reduce this cost was to limit the time spent on counselling or by using lower-paid personnel for counselling activities.

Conclusion

The economic evaluation results presented here can guide program managers and health policy decision makers in the research for efficient HIV testing options, for the proper allocation of healthcare resources and for adoption of models of healthcare delivery that represent the best value for money.
P1-S4.31 Failure of respondent driven sampling in a transgender population due to inadequate formative work and non-network associated selection criteria
Authors: Risser J , Padgett P , Montealegre J
Published: July 2011

Background

In 2009, the CDC funded the Transgender HIV Behavioural Surveillance pilot to assess the feasibility of using respondent driven sampling (RDS) to recruit ethnic minority male-to-female transgender (MTFTG) participants. RDS is a chain-referral strategy that restricts the number of people each participant can recruit and offers incentives for both participation and recruitment. With proper adjustment for sampling, data collected through RDS can be used to develop population prevalence estimates. RDS assumes that respondents know one another as members of the target population.

Methods

Because of funding constraints, formative work and data collection lasted only 4 months. Our goal was to recruit 100 MTFTG participants, at least 15 years old, who were assigned male sex at birth and who currently identified or presented as female. We established a field office in the Houston Transgender Center and identified a charismatic MTFTG interviewer. Office hours were set for early afternoon; incentives were $20 for the interview and $10 for each recruit (up to $50). Recruiter instructions were to give the RDS coupon to known Latina or Black MTFTG.

Results

Our University prohibited the hiring of our first-choice interviewer because she had a previous moral turpitude conviction. Recruitment was delayed until we hired another. We planted 11 seeds; 5 failed, 3 recruited 7 individuals in 2 waves; and 3 recruited 40 individuals with the longest chain consisting of 6 waves. We distributed 201 coupons and interviewed 48 eligible and consenting MTFTG.

Conclusions

Formative work is essential to identify the size and features of the study population social networks, time and place for recruitment, and appropriate incentive. RDS requires respondents to be linked by the target attribute, in this case ethnic minority MTFTG. By restricting recruitment to transgender individuals of colour, we violated that assumption. Our sample networks were not structured around race/ethnicity; rather they were networked through work affiliations (sex worker, performer, unemployed). Recruitment also failed because the incentive was not enough to encourage performers and sex workers to participate in a health survey. Evening hours would have been better for our group's work schedules so they could participate on their way out for the evening. Our failure to get RDS initiated reinforces the importance of formative work to determine if RDS will succeed in your target population.
P1-S4.34 Can RDS be used to recruit unbiased samples from the same population with repeated sampling?
Authors: Risser J , Padgett P , Montealegre J
Published: July 2011

Background

Respondent Driven Sampling (RDS) is a modified snowball sampling method that allows for recruitment of a probability sample, even when we cannot enumerate the population of interest. The National HIV Behavioural Surveillance project, designed to assess trends in risky behaviours, used RDS to recruit injection drug users (IDU) and heterosexuals at high risk of HIV infection (HET). In order to examine changes in behaviours over time, the sampling method must recruit homogeneous populations, so that observed differences across cycles can be attributed to changes in behaviour, rather than to errors in recruitment. This analysis was designed to determine if crude and adjusted measures within and between the IDU and HET cycles, are homogeneous on basic demographic characteristics. Our goal to assess if the samples may be considered to be from the same target population.

Methods

Data are from the Houston Texas site of NHBS-IDU 1 and 2 (2005, 2009), and HET 1 and 2 (2006, 2010). Adjusted population prevalence estimates are calculated using RDSAT, adjusting for design effect and sampling characteristics. Estimates were compared using the Mantel Haenszel test for heterogeneity.

Results

Comparing IDU1 to IDU2, we found similar population estimates (p for heterogeneity >0.05) for age 40–49 years; Black race; had current health insurance; and currently homeless. The populations differed (p for heterogeneity <0.05) by the proportion that: graduated from high school; were arrested in the last year; and visited a doctor in the last year. Comparing HET1 and HET2, we found similar population estimates for the proportions that: had health insurance; visited a doctor in the last year; were arrested in the last year; graduated from high school; and were aged 30–49. The populations differed in the percent: Black; currently homeless; and aged 18–29.

Conclusion

Using RDS to assess behaviour changes over time will be difficult if the study samples do not represent a fixed population. We looked at variables we thought would be stable over the two cycles and were surprised to find instability. With these differences, we cannot attribute the observed changes in risky behaviour solely to prevention efforts that occurred between the surveillance cycles. However, RDS remains an exceedingly easy and efficient sampling method and with appropriate multivariable analysis techniques can be used with repeated samples over time.
P1-S1.18 Investigating a cluster of neonatal herpes at a single institution
Authors: Desai N , Schillinger J , Bratu S , Eramo A , Bowers C , Agrawal A
Published: July 2011

Background

Neonatal herpes (NH) is a reportable disease in New York City (NYC); annual incidence is ∼12/100 000 live births; rates are highest among young, and Black non-Hispanic women. Over a 6-month period at our institution, we identified four neonates with disseminated NH. We investigated the cluster to rule out a nosocomial cause.

Methods

NH incidence was calculated for the institution and demographics of delivering mothers compared to NYC overall. NH cases were characterised with regard to viral type, birth history, syndrome classification, vital status, maternal serum antibody status, and herpes viral isolates were sought. We reviewed electronic medical records to identify staff common to >2 case-mothers or -infants. We interviewed staff about signs/ symptoms of herpes simplex virus (HSV) infection over the last year, or close contact with a family member with HSV. Maternal hospital rooms, infant isolettes, and ventilators were mapped to rule out common use by case-mothers or -infants. As NH cases were identified, protocols were implemented for notifying paediatrics of maternal post partum fever, and for initiating empiric treatment with IV acyclovir for neonates of febrile mothers.

Results

The NH incidence rate at our institution (151/100 000 live births) was >10 times NYC incidence. Women delivering at our institution were younger (41% vs 27% NYC-wide aged <25), and more likely to be Black non-Hispanic (85% vs 22% NYC-wide). Details for case-infants are presented in Abstract P1-S1.18 table 1 below. Among three mothers to case-infants with type 2 HSV, two were antibody positive and one was negative, suggesting she may have had recent infection unapparent at delivery. Herpes viral isolates were retained for only 1 of 4 case-infants. The four case-mothers were delivered by four different obstetricians. Among 11 staff common to >1 case-infant, none had any history or symptoms of HSV infection; no equipment was common to the case-infants and no mothers shared a common room.

Abstract P1-S1.18 Table 1MonthHSV TypeGest. Age (wks)Delivery TypeAge at first sign (days)Mat Age (yrs)Mat hx of lesionsPost Partum feverMat HSV IgMMat HSV IgGOutcomeCase 1Apr136Vaginal418NoneYesNANAExpiredCase 2May239C Section419NoneYesPosNegSurvivedCase 3Jul239+Vaginal1937NoneNoPosPosExpiredCase 4Oct233Vaginal321NoneYesNegNegExpired

Gest, gestational; mat, maternal; hx, history.

Conclusions

NH surveillance data provided important context for this investigation; incidence at this institution was much greater than expected, but the patient population is at increased risk for NH. Available data do not support a nosocomial cause for this cluster; retention of neonatal herpes viral isolates would have aided this investigation. Early recognition of the cluster by the treating team and prompt involvement of national and state public health agencies helped guide the investigation and establish novel preventive and empirical treatment protocols.
P1-S5.02 Towards more robust estimates of the per sex act transmission probability ofChlamydia trachomatis
Authors: Althaus C , Low N
Published: July 2011

Background

Estimating the per sex act transmission probability ofChlamydia trachomatisis necessary to assess an individual's risk of infection and re-infection after sexual contacts with chlamydia-positive partners. Katz (1992,Stat Med) made one of the first attempts to estimate the probability of chlamydial transmission based on data about the proportions of concordant (both partners infected or uninfected) and discordant (only one partner infected) couples tested for chlamydia. This provides a cross-sectional per partnership transmission probability but did not address the duration of sexual partnerships and the spontaneous clearance of chlamydia. Mathematical models can be used to take these complexities into account.

Methods

We developed a simple mathematical model of chlamydia transmission that incorporates the formation and dissolution of sexual partnerships. Chlamydia can be transmitted from an infected to an uninfected partner throughout the duration of the partnership. Infected partners can also clear chlamydia spontaneously. The model was fitted to published data from a cross-sectional study of chlamydia infection status in heterosexual couples at a US sexually transmitted diseases clinic. The model was further parameterised with study data about overall chlamydia positivity and the number of sexual partners in the last 6 months.

Results

The data showed similar proportions of infected female partners of infected men and infected male partners of infected women, suggesting similar transmission probabilities. Assuming an average infectious duration of 12 months for women and men, we obtained best-fit estimates for the transmission rate (0.0064 per day) and average duration of partnerships (6.0 months) in the study. The transmission rate per day corresponds to a per sex act transmission probability of 4.5%, assuming one unprotected episode of coitus per week in a partnership. Our analysis also shows that these estimates depend on the assumed infectious duration of chlamydia.

Conclusions

Our approach shows how the dynamics of sexual partnership formation and disease transmission can be taken into account to derive the daily rate of chlamydia transmission within a partnership. The per sex act transmission probability can then be inferred. These refined estimates will help to parameterise future mathematical models of disease transmission and assess the risk of infection and re-infection after sexual contacts with chlamydia-positive partners.
P1-S5.03 Pattern of sexually transmitted infections (STIs) in hormonal contraceptives and intra-uterine devices (IUD) users attending family planning clinics in Ibadan, Nigeria
Authors: Fayemiwo S A , Fatiregun A A , Bakare R A
Published: July 2011

The large majority of women who acquire HIV and other sexually transmitted infections (STIs) are in their childbearing years and are current or potential users of contraceptive methods. Using contraceptives has two main benefits; the primary benefit of preventing unplanned pregnancy and the potential secondary benefit of protecting against sexually transmitted infections (STIs). Unfortunately, the contraceptive with the best records for pregnancy prevention offers little if, any protection against STIs. The study aimed at assessing the pattern of sexually transmitted infections among hormonal contraceptives and intra-uterine contraceptive devices users attending family planning clinic, University College Hospital Ibadan.

Methods

This is a cross-sectional study in a population of women using Intra-Uterine Contraceptive Devices (IUCD) and hormonal contraceptive methods attending Family Planning clinics at University College Hospital, Ibadan. Detailed medical history, Endocervical and high vaginal swabs were collected from the participants to establish diagnosis after clinical examination and informed consent.

Results

There were 200 participants with a mean age of 31.92 years (SD=8.33, range=16–55). The mean age of sexual debut of participants with any STI was 19.5 years. 102 (51.0%) of the women were using different methods of hormonal contraceptives while 84 (42.0 %) had intrauterine contraceptives devices inserted. About 54.5 % (109) had various STIs in both groups. The most common STI diagnosed was bacterial vaginosis (26.5%). Other STIs diagnosed were vaginal candidiasis (26.0 %), HIV (8.5%), trichomoniasis (7.5%), Chlamydia cervicitis (7.0%), syphilis (3.5%), Genital warts (3.5 %) and gonorrhoea (2.5 %). Even though bacterial vaginosis and candidiasis were diagnosed more in women with IUCD while Chlamydia cervicitis, syphilis and gonorrhoea occurred more in women using various types of hormonal contraceptives, there was no statistical relationship between the STIs and their sexual behaviours.

Conclusion

Women seeking contraception to prevent unintended pregnancy are as much in need of education about prevention of STIs as much as the counselling regarding the most effective contraceptive methods. Younger age, increased numbers of sexual partners and oral mode of sexual intercourse were significantly associated with increased risk of acquiring vaginal tric.
P1-S5.07 Ongoing risk behaviours: new STD diagnoses in persons known to be HIV-infected in Miami-Fort Lauderdale (South Florida), 2000–2009
Authors: Peterman T A , Brewer T H , Newman D R , Shiver S
Published: July 2011

Background

The diagnosis of a new bacterial STD in a person with documented HIV- infection suggests ongoing high-risk sexual behaviours. While high rates of syphilis among HIV-positive MSM have been repeatedly noted in South Florida, little attention has been given to the incidence of gonorrhoea (GC) and chlamydia (CT) among HIV-positive individuals, due to use of separate surveillance systems, differing security requirements, and limited partner services staff available to investigate GC and CT cases.

Methods

We reviewed STD surveillance data from 2000 to 2009 after linking it to the HIV/AIDS surveillance data base. We analysed cases of GC and CT diagnosed >60 days after an HIV diagnosis.

Results

Overall 3.7% of GC (1504 of 40 214) and 1.2% of CT (1149/99 265) cases were in persons known to be HIV- positive. The percentage of cases diagnosed in HIV- positive persons increased steadily over the time period; GC coinfections increased from 2.3% in 2000 to 5.0% in 2009 and CT coinfections increased from 0.8% to 1.3%. Most of the GC coinfected cases were among males; 1144/21 360 (5.4%) of males with GC were coinfected with HIV while 360/18 854 (1.9%) of females with GC were coinfected with HIV. For CT, 559/22 735 (2.5%) of males with CT were coinfected with HIV while 590/76 530 (0.8%) of females with CT were coinfected with HIV. Most coinfections were among HIV positive males, 73.5% of whom were men who have sex with men (MSM). Coinfections among men increased over the time period, while among women the number peaked in 2006 and has declined thereafter. HIV- positive men accounted for over 10% of GC infections among men 35–59 years of age and over 10% of CT infections among males 40–59. HIV coinfection was present for over 5% of GC infections among women 30–44 years of age and 50–54 years of age.

Conclusions

While males with GC or CT who are coinfected with HIV constitute a small fraction of the cases in South Florida, the proportion is increasing steadily. HIV+ MSM account for a high percentage of cases among males over 35 years of age. Timely, accessible linkage between HIV and STD databases is essential to direct partner services and risk reduction counselling to this high-risk population.
P1-S5.08 Attendance at local and national sex-events associated with STD diagnosis, San Francisco, 2010
Authors: Bernstein K , Hjord H , Marcus J , Kohn R , Philip S
Published: July 2011

Background

A variety of sex-themed events draw crowds from across the USA and provide opportunities for sex partner recruitment, potentially amplifying local sexual networks and complicating disease prevention and control. We examined the frequency of attendance at such events and the association between attendance and incident STD diagnosis among patients visiting a municipal STD clinic.

Methods

During 21 September 10–1 November 10, patients seeking services at San Francisco City Clinic were invited to complete a survey about their attendance at local and national events in the prior 12 months, including street fairs, gay pride events, Burning Man, leather events, and circuit parties. Survey results were linked with data from the clinic visit, including self-reported risk behaviours and STD diagnoses. Analyses were stratified by sexual orientation. Events traditionally associated with sex partner recruitment (sex events) were combined. χ2and Wilcoxon rank-sum statistics were used to compare patients who attended sex events with all other patients completing the survey.

Results

Of the 246 completed surveys, 106 (43.1%) were among heterosexual patients and 140 (56.9%) were among men who have sex with men (MSM). Twenty per cent of heterosexual patients and 47% of MSM patients reported attending a sex event in the prior 12 months. Among heterosexual patients, those attending a sex event were of younger age (median 25 vs 29 years, p=0.014), reported fewer sex partners in the prior 12 months (median 1 vs 2, p=0.021) and were more likely to be at their first visit to the STD clinic (71.4% vs 47.1%, 0.045). There was no association between STD diagnosis and event attendance among heterosexuals. Among MSM, those attending sex events reported more sex partners in the prior 12 months (median 10 vs 5, p=0.019), were more likely to be residents of San Francisco (83.3% vs 66.2%, p=0.021), and were more likely to be diagnosed with chlamydia (15.2% vs 4.1%, p=0.024) or any STD (29.0% vs 14.9%, p=0.045) at that visit.

Conclusions

Attendance at sex events was common among patients at an urban STD clinic. Among MSM, attendance was associated with more sex partners and STD diagnosis. The ability of local programs to successfully prevent and control STDs may be complicated by recruitment of new sex partners at such events. Innovative collaborative prevention interventions at sex events and for residents returning from such events should be explored.
P1-S5.12 Population attributable risk for chlamydia infection in a cohort of young international travellers (backpackers) and residents in Australia
Authors: Wand H
Published: July 2011

Aim

To estimate the population attributable risk (PAR) forChlamydia trachomatisinfection in young men and women in Sydney, Australia.

Method

Multivariate logistic regression was used to examine the association between demographic, sexual behaviour and other potential risk factors on chlamydia positivity in young (≤30 years) heterosexual international travellers (backpackers) and Australian residents attending a sexual health clinic. Point and interval estimates of PAR were calculated to quantify the proportion of chlamydia infections that can theoretically be prevented if a combination of risk factors is eliminated from a target population.

Results

In males, the PAR associated with inconsistent condom use in the past 3 months was 65% (95% CI 56 to 71%) in backpackers compared to 50% (95% CI 41 to 56%) in non-backpackers and the PAR associated with reporting three or more female sexual partners in the past 3 months was similar between male backpackers and non-backpackers; 33% (95% CI 28 to 40%) and 36% (95% CI 32 to 41%), respectively. In females, the PAR associated with inconsistent condom use in the past 3 months was 51% (95% CI 42 to 59%) in backpackers compared to 41% (95% CI 31 to 51%) in non-backpackers, and the PAR associated with reporting three or more male sexual partners in the past 3 months was 14% (95% CI 11 to 18%) in backpackers compared to 30% (95% CI 25 to 37%) in non-backpackers.

Conclusion

These findings suggest that the largest number of chlamydia infections could be avoided by increasing condom use, particularly in backpackers. Reporting multiple partners was also associated with a large proportion of infections and the risk associated with this behaviour should be included in health promotion strategies.
P1-S5.13 Recreational drug use during sex is associated with STI among clients of a large STI outpatient clinic in Amsterdam, The Netherlands
Authors: Heiligenberg M , Wermeling P , van Rooijen M , Urbanus A , Prins M , Coutinho R , Schim van der Loeff M
Published: July 2011

Background

Previous studies have shown that recreational drug use is associated with high-risk sexual behaviour and STI. Little is known about the relationship between the use of specific recreational drugs during sex, sexual behaviour and the risk for any STI (chlamydia (CT), gonorrhoea (NG) and/or syphilis) or the three STI separately in heterosexual men, men having sex with men (MSM) and women. We assessed the prevalence of recreational drug use during sex, and assocations of drug use during sex with high-risk sexual behaviour and STI.

Methods

Attendees of the STI clinic of the Public Health Service of Amsterdam were interviewed during three waves of a bi-annual anonymous survey (2008–2009) about sexual behaviour in the preceding 6 months (number of steady and casual sex partners, condom use during vaginal or anal sex) and specific recreational drug use just before or during sex in the preceding 6 months (cannabis, XTC, poppers, heroine, cocaine, GHB, apomorfine, amphetamine, methylamphetamine, mushrooms, ketamine and explosion). Participants were tested for CT, NG and syphilis. Associations between drug use during sex and high-risk sexual behaviour and STI were analysed using multivariable logistic regression analyses. Analyses were done separately for heterosexual men, men who have sex with men (MSM) and women.

Results

In total, 1012 heterosexual men, 749 MSM and 1254 women participated in this study. Of these, 11.7% had CT, 3.5% NG and 1.4% syphilis. Recreational drug use during sex in the previous 6 months was reported by 22.5% of heterosexual men, 52.7% of MSM and 15.6% of women. In all three groups, drug use during sex was associated with unprotected vaginal and anal sex and more casual sex partners. In multivariable analyses among MSM, adjusting for age, ethnicity, educational level and sexual behaviour, poppers use was associated with any STI (adjOR 1.8, 95% CI 1.2 to 2.6) and with NG (adjOR 2.6, 95% CI 1.6 to 4.2), and GHB use with syphilis (adjOR 2.3, 95% CI 1.0 to 5.0). In multivariable analyses among women, GHB use was associated with any STI (adjOR 4.7, 95% CI 1.8 to 12.2) and CT (adjOR 3.5, 95% CI 1.1 to 11.4). In heterosexual men, drug use during sex was not associated with STI.

Conclusions

STI clinic clients frequently report recreational drug use during sex and this is associated with high-risk sexual behaviour in heterosexual men, MSM and women. The use of drugs during sex is associated with STI in MSM and women, but not in heterosexual men.
P1-S5.16 Investigating self-reported level of condom use and condom use in last act among high-risk groups in Southern India
Authors: Pickles M , Adhikary R , Mainkar M ,   R S P, Deering K , Verma S , Boily M C , Vickerman P , Alary M
Published: July 2011

Background

Measuring consistent condom use (CCU) is crucial in understanding the trajectory of the HIV epidemic and in evaluating HIV preventive interventions that promote condom use. We examine how one measure of CCU varies across different populations, and compare it to condom use in the last sex act.

Methods

Using data from cross-sectional behavioural and biological surveys (2005–2007), we compare responses concerning self-reported level of condom use and condom use in the last act by female sex workers (FSWs), their clients, and men who have sex with men (MSM) in districts from Andhra Pradesh, Maharashtra and Tamil Nadu states in India. For FSWs/clients, the question related to sex with occasional clients/FSWs. For MSM, the question was for non-commercial, non-regular male partners. The time period was unspecified. Levels of condom use were defined as every time", “most of the time/sometimes”, and “never”. We define CCU as those who reply “every time”.

Results

95.2% of all FSWs reported using a condom in the last act, compared to 72.9% of clients and 80.0% MSM. However, only 36.7% of clients and 29.6% of MSM reported CCU compared to 80.0% of FSWs. Abstract P1-S5-16 table 1 shows condom use in the last act stratified by reported level of condom use. For all populations reporting CCU “always”, condom use in the last act was >98%. Of those who reported “most of the time/sometimes”, there was a significant difference between condom use in the last act between clients and the other groups (χ2test, p<0.001), with clients using condoms less frequently. Condom use in the last act among those who “never” use a condom was low (<3%).

Abstract P1-S5.16 Table 1

Results from IBBA surveys in Andhra Pradesh, Maharashtra and Tamil Nadu states

Report using a condom “every time”Report using a condom “sometimes/most of the time”Report using a condom “never”Used a condom in last sex actReport using a condom “every time”Report using a condom “sometimes /most of the time”Report using a condom “never”FSW80.00% (4010)19.01% (953)0.96% (93)98.28%87.20%2.08%Client36.67% (1667)48.20% (2191)15.13% (688)98.50%75.58%2.03%MSM29.63% (621)63.63% (1648)12.39% (321)99.36%88.17%1.25%

Conclusions

CCU may not accurately reflect number of acts protected by condoms. Among males in particular, dividing condom users into CCU and non-CCU neglects many who almost always use condoms, and so will still have a high degree of protection. These individuals are an important group to consider when evaluating the effect of changes in condom use on the HIV epidemic, especially among MSM. HIV prevention programmes should try to identify reasons explaining lower CCU among MSM and clients who already use condoms “most of the time/sometimes”, and endeavour to increase consistency within this group.
P1-S5.25 Acyclovir and transmission of HSV-2 from HSV-2/HIV-1 dually infected persons
Authors: Mujugira A , Margaret A , Celum C , Lingappa J , Baeten J , Fife K , De Bruyn G , Bukusi E , Corey L , Wald A
Published: July 2011

Background

Daily suppressive therapy with valacyclovir reduces the risk of sexual transmission of HSV-2 in healthy HSV-2 serodiscordant heterosexual couples by 48%. Whether suppressive therapy reduces HSV-2 transmission from persons who have both HIV-1 and HSV-2 is unknown.

Methods

Within a randomised trial of daily acyclovir 400 mg bid in African HIV-1 serodiscordant couples, in which the HIV-1 infected partner was HSV-2 seropositive, we identified partnerships in which the HIV-1 susceptible partners were HSV-2 seronegative. Cox proportional hazards analysis was used.

Results

We followed 911 HIV-1 and HSV-2 serodiscordant couples for a median of 18 months (IQR 3, 24). For 112 couples (12%), the HIV-1/HSV-2 infected partner was male, of whom 37% (34/91) were circumcised. 68 HSV-2 seroconversions were observed (an incidence of 5.1 per 100 person-years): 40 in the acyclovir group and 28 in the placebo group (HR 1.4, 95% CI 0.8 to 2.2; p=0.2). In a multivariate analysis of HSV-2 susceptible women, hormonal contraception (HR 3.84, 95% CI 1.32 to 11.14, p=0.013) and having an uncircumcised male partner (HR 8.91, 95% CI 1.17 to 67.85, p=0.035) were significant risk factors for HSV-2 acquisition. Among HSV-2 susceptible men, younger age was the only significant HSV-2 risk factor (p=0.014).

Conclusions

Suppressive acyclovir therapy did not decrease the risk of HSV-2 transmission within HSV-2-serodiscordant couples in which the HSV-2-seropositive partner also had HIV-1 infection. Hormonal contraceptive use and lack of male circumcision in the HIV-1/HSV-2 dually infected male partners increased the risk of HSV-2 acquisition among initially HSV-2 seronegative women.
P1-S5.26 Better-understanding of the dynamics of gonorrhoea and chlamydia through analysis of coinfection
Authors: Turner K , White P , Garnett G , Gay N , Low N , Althaus C ,   Partner Notification Group
Published: July 2011

Background

Coinfection with gonorrhoea and chlamydia occurs frequently. It is well known that the proportion of gonorrhoea-infected individuals who also have chlamydia is higher than the proportion of chlamydia-infected people who also have gonorrhoea. This difference has implications for the detection and management of infections and might simply reflect the higher prevalence of chlamydia than gonorrhoea in the general population. The objective of this study was to explore the characteristics of chlamydia–gonorrhoea coinfection in a transmission dynamic model and determine whether levels of coinfection might give insights into hard-to-measure behavioural parameters such as mixing patterns.

Methods

We designed a simple transmission dynamic model to capture gonorrhoea and chlamydia dynamics within a heterosexual population. We fitted the model to empirical surveillance data (Gonococcal Resistance Antimicrobials Surveillance Programme, GRASP) about levels of infection and the NATSAL 2000 sexual behaviour survey. The baseline prevalence of chlamydia was 2.6%. We tested whether the model replicated the observed prevalence of coinfection. We then extended the model to improve its realism and capture potential interactions including cotreatment, cotransmission, short term acquired immunity or changes in symptom severity or susceptibility.

Results

The best fitting model predicts a gonorrhoea prevalence of between 0.4 and 0.7% and of those with gonorrhoea 15% (men) and 17% (women) also have chlamydia, compared with empirical estimates of 28% (men) and 38% (women). Of those with chlamydia, 3.0% and 2.6% of men and women are coinfected with gonorrhoea. The model also predicts an increasing prevalence of coinfection with increasing sexual activity.

Conclusions

A trend of increasing coinfection with increasing sexual activity is observed in the empirical data for men, but not women: the highest risk women with gonorrhoea have lower levels of chlamydia then the moderate activity women. The best fitting models underestimate the level of coinfection observed. Cotreatment and temporary immunity to chlamydia do not appear sufficient to explain the differences between the model and observations. Differences in coinfection levels are a complex phenomenon that do not just reflect differences in population prevalence and are not captured by the simplest models.
P1-S5.27 Low prevalence of asymptomatic STI in HIV-infected heterosexual males and females, visiting an HIV outpatient clinic in the Netherlands
Authors: Heiligenberg M , van der Loeff M S , de Vries H , Geerlings S , Prins M , Prins J
Published: July 2011

Background

In the Netherlands no guidelines exist for routine STI screening of HIV-infected patients. In a study in two academic hospitals in the Netherlands, 16% of HIV-infected MSM in HIV care had an asymptomatic STI, making regular STI screening in this group appropriate. It is unclear whether regular STI screening should also be considered for HIV-infected heterosexual men and women. Therefore, we studied the prevalence of, and factors associated with asymptomatic STI in a representative group of HIV positive heterosexual men and women.

Methods

HIV-1 infected heterosexual patients visiting the HIV outpatient clinic of the Academic Medical Center in Amsterdam, the Netherlands, were screened for STI during a routine visit. Patients spontaneously reporting symptoms compatible with STI were excluded.Chlamydia trachomatis(CT) andNeisseria gonorrhoeae(NG) were tested by PCR on throat swabs, vaginal or anal self swabs and urine samples, depending on gender and sexual behaviour. Hepatitis B virus (HBV) and hepatitis C virus (HCV) serology were performed and patients were screened for syphilis by TPHA and RPR. Participants were interviewed by a trained interviewer about sexual risk behaviour in the previous 6 months.

Results

Between October 2007 and June 2008, 248 men and women (median age 41 years, range 18–82) were included. 56% was female and 42% had Dutch ethnicity, the main other ethnicities were Ghanese, Surinamese/Antillean and Sub-Saharan African. The Abstract P1-S5.27 table 1 shows sexual behaviour of participants in the preceding 6 months. Reported history of STI in the last 6 months was 2%, and lifetime history of STI (non-HIV) was 49%. 29% of participants had had STI testing in the preceding 6 months, and 64% had an STI test more than 6 months ago. Only four patients (1.6%) had an asymptomatic STI. Two women were diagnosed with vaginal CT, 1 man with urethral CT and a female intravenous drug user with a history of syphilis had a new syphilis infection. We also identified one hitherto undiagnosed HCV infection; this was in a male intravenous drug user without a history of sex with men; we did not classify this as an STI.

Abstract P1-S5.27 Table 1

Sexual behaviour of HIV-infected heterosexual males and females visiting an HIV outpatient clinic in the Netherlands, 2007–2008

Sexual behaviour+/total%Did not have sex in last 6 months65/19733.0Had 1 sexual partner last 6 months110/19360.1Had 2 or more sexual partners last 6 months19/1939.8Had casual sexual partner(s) in last 6 months24/19312.4Had unprotected vaginal sex in last 6 months46/19320.7Had unprotected anal sex in last 6 months4/1932.0

Conclusions

In this population of HIV-1 infected heterosexual patients in care for HIV infection high risk sexual behaviour is rare and asymptomatic STI are uncommon. Our study results suggest that routine screening in asymptomatic heterosexual patients is currently not needed.
P1-S5.37 Evolution of sexual networks over time in Manitoba, Canada
Authors: Jolly A
Published: July 2011

Background

Recent increases in bacterial STI in Canada and the resurgence of syphilis require further investigations into the transmission of STI. Specifically, adaptation of sexual networks and sexually transmitted pathogens to prevention efforts such as screening and partner notification have been proposed as a major factor in persistence of STI. We investigate the size and morphology of sexual networks generated by routinely collected contact tracing data for gonorrhoea, chlamydia and syphilis for the whole province of Manitoba, at three time points; 1990–1992; 1997–1998, and last, from 2002 to 2003.

Methods

We compared the sizes of the components in which cases and contacts were connected by sexual intercourse at the three time points, and cross matched chart numbers of the cases from 1990–1992 with those from 1997–1998 in order to identify which individuals were active within specific networks 8–10 years later. We reviewed the changes in the networks along with the rates over time in order to assess the epidemic phases of the pathogen and their possible effects on the networks.

Results

From 1990 to 1992, 20 223 cases were available for analysis; from a 6-month period in 1997–1998, 4544 cases and contacts were available, and last for 2002–2003; 8746 cases and contacts were available over 2 years. For the first 3-year period, components ranged from 1 to 2166; in 1997–1998; from 1 to 82 people, and from 1 to 33 people in 2002–2003. The giant component decreased by an order of magnitude over time as a proportion of all components, consisting of 9.4% of the population in the first time period, 1.8% in the second, and 0.4% (Abstract P1-S5.37 figure 1). Twenty people who had chlamydia or gonorrhoea in 1990–1992 had subsequent STIs every 2–3 years up to an including 1997–1998. They were significantly younger than other cases, (means 17.81, 23.27, p=0.0002) and were more likely to be of North American Indian ancestry (OR14.22, p<0.0001). They did not differ by area of residence or gender and the sizes of the components in which all cases and contacts were connected by sexual intercourse in 1997/98 were similar to those in which the 20 long term repeaters were active.

Abstract P1-S5.37 Figure 1

Evolution of sexual networks over time in Manitoba, Canada A) Pruned largest component, n=2, 166, 1990–1992, B) Largest component n=82, 1997–1998 and C) largest component n=33, 2003–2004.

Conclusions

The existence of 20 young, First Nations people who had STI at least every 2–3 years from 1990–1998 provides evidence that the STD core group likely consists of some of the same people over a 7–9-year period, who by virtue of their repeated infections contribute disproportionately to STI transmission. The decrease in size of the large components together with decreases in STI supports the hypothesis that eco-niches of STI adapt to control programs over time.