bluuebunny/crossref_metadata_2025 huggingface dataset:
P1-S2.51 Sexually transmitted HCV in MSM in Montreal
Authors: Thomas R , Vezina S , Machouf N , O'Brien R , Huchet E , Longpré D , Lavoie S , Milne M , Asselin F , Trottier B
Published: July 2011

Methods

A retrospective analysis of the clients who attend the “Gay Screening Clinic” (GSC) at Clinique medical l'Actuel (Montreal, Canada) between May 2009 and April 2010 was conducted.

Results

Among the 1010 patients included in the analyses we found five cases of new HCV infection which seems to be acquired by sexual transmission. All of them were male and MSM, none of the cases had previous history of IDU, but three reported having had sexual relation with IDU partners. All of them were previously vaccinated for Hepatitis A and B and screened for HIV. None of them were coinfected with HIV, but one was coinfected with Syphilis and one with Gonorrhoea. Patients infected with HCV were older than non HCV patients (37 years vs 32 years) and had a higher number of sexual partners during the last 12 months (16 part. vs 9 for the non HCV patients). One of the HCV cases reported not having anal intercourse, two reported having had occasional unprotected anal intercourse and two reported always using condom for anal intercourse.

Conclusions

As in other urban centers, cases of sexually transmitted HCV had also been found in Montreal. This prevalence of 0.5% is very low compared to our HIV population in which the prevalence of sexually transmitted HCV is 3%. The particularity of MSM with recently acquired HCV by sexual transmission seems to be related to their engagement in sexual relation with high number of concurrent partners.
P1-S2.52 Risk factors for STIs among MSM attending a sexually transmitted disease clinic in Montreal, Canada
Authors: Machouf N , Thomas R , O'Brien R , Vezina S , Longpré D , Legault D , Milne M , Fafard J , Trottier B
Published: July 2011

Background

Often STIs are not diagnosed and not treated because people don't have access to appropriate healthcare screening facilities and to care. At Clinique l'Actuel (Montreal, Canada) we developed Gay Screen Clinic (GSC) as a new concept giving rapid access to men who have sex with men (MSM) to an appointment for STI screening. We then assessed the extend and risk factors of STIs in a population of men having sex with men (MSM) attending the GSC.

Methods

We did a retrospective analysis of the last 1000 attendees to the GSC at Clinique l'Actuel in 2009−2010. Multivariable analyses were conducted to identify the factors associated with history of STIs.

Results

Participants were all MSM with a mean age of 32 years (ranged from 18 to 70 y). In total, 50% (n=506) of them self reported history of STIs and 236(24%) of them had a positive sexual health screen at this visit. STI diagnoses included genital herpes (n=105, 14 %), condylomes (n=79, 8%), syphilis (n=43, 5%), chlamydia infection (n=32, 3%), HIV (n=10, 1%), Gonorrhoea (n=9, 1%) and HCV (n=5, 1%). 32% of the attendees had sexual relations in bath houses and 43% with anonymous contacts. In multivariate analyses, past history of STI was significantly associated with higher age (OR=1.02, p=0.001), higher number of sexual partners in the last 12  months (OR=1.02, p=0.015), having sexual contact in bath houses (OR=1.46, p=0.021) and with unknown partners met through internet or in backrooms (OR=1.53, p=0.004), using recreational drugs (OR=2.01, p=0.001) and having only male partners (OR=1.60, p=0.023) rather than male and female sexual partners.

Conclusions

STIs were common among non HIV MSM attending the GSC in Montreal. Even after many years of prevention campaign MSM still have high risk sexual behaviour. Physician should routinely enquire about drug use of their patients in order to prevent new STIs. Targeting specific sexual networks is needed to be more effective.
P1-S1.11 Prevalence ofTrichomonas vaginalis, chlamydia and gonorrhoea in women at the Miami-Dade County Health Department STD Clinic
Authors: Tookes H , Hirsch N , Diaz C , Ponomareva O , Castro J G
Published: July 2011

Background

Miami, Florida, has the highest rate of HIV diagnoses in the USA (70.3 per 100 000 people), accounting for 1218 of the 41 269 incident HIV cases nationwide (2008). AlthoughTrichomonas vaginalis(TV) infection has been associated with an increased risk of HIV acquisition in women, the prevalence of TV in Miami is unknown due to lack of routine screening and low sensitivity testing methods. The purpose of this study is to establish a prevalence of TV in women seeking services at the Miami-Dade County Health Department Downtown STD Clinic compared to the prevalence of routinely screened STDs, gonorrhoea (GC) and Chlamydia (CT).

Methods

This study analyses baseline data from the Miami site of Project AWARE which is a multi-centre randomised clinical trial that seeks to test the effectiveness of risk reduction counselling in preventing sexually transmitted infections including HIV among HIV-negative persons. Eligibility criteria for Project Aware included negative or unknown HIV status, age of 18, and ability to provide informed consent. We recruited 251 women aged 18–64 for STD screening. The screen included FDA-approved Aptima GC/CT NAAT (nucleic acid amplification test) and a newly validated Aptima TV NAAT. Specimens were collected by vaginal swab performed either by a clinician or the patient. Additionally, we report the TV diagnoses given the current clinic protocol in which only symptomatic women received a wet mount analysed by light microscopy. We use descriptive statistics to report the prevalence of GC, CT and TV (as diagnosed by NAAT and wet mount) in our clinic.

Results

Of the 251 women in our study, 163 high-risk populations. Received a wet mount. By wet mount, we found a 9% prevalence of TV in our patients. Comparatively, when all 251 patients were screened using NAAT, the TV prevalence was 20%. The prevalence of CT was 14% and GC was 6%.

Conclusions

TV is the most prevalent STD in patients in our clinic which draws upon high-risk individuals in urban Miami. TV infections were greater than CT, often believed to be the most prevalent STD in our population. Further, the routine screening using the TV NAAT detected 27 cases of TV that would have been undiagnosed given current clinic protocol. Since Miami, FL has the highest prevalence of HIV in the country and TV infection has been linked to new HIV infection, we believe that routine TV screening by NAAT should be instituted in high-risk populations.
P1-S2.58 The role of venues in structuring STI and risk networks among men who have sex with men
Authors: Drumright L , Weir S , Frost S
Published: July 2011

Background

Venues (eg, bars, the Internet) are believed to structure STI risk networks, however it is difficult to separate “risky places” from “risky people”, as venues are comprised of the people who attend them. To determine how venues may structure HIV/STI risk, we analysed data collected within social meeting places with “causal inference” statistical approaches, which aim to mimic randomising individuals to venues.

Methods

Between 11/2007 and 3/2009, we visited 14 venues in San Diego, California, previously identified as places where men meet male sexual partners. 660 male patrons were interviewed anonymously by computer assisted self interview; 609 reported having ever had sex with a man. We analysed associations between the interview venue and participants' demographics, self-reported HIV and STI status, risk behaviours, and drug use. We used a marginal structural model to test associations between HIV/STI and venue, weighting by age, ethnicity, education, number of sexual partners in the past year, and number of HIV+ individuals known, in order to control for collinearity between venue and these patron characteristics.

Results

The mean age of MSM was 34 yrs; 55% reported white, 24% Hispanic, and 8% African American ethnicity; 89% reported at least some college education. 35% reported history of STI and 13% reported that they were HIV-infected. The median number of lifetime male partners reported was 30, with 15% reporting unprotected receptive anal sex with at least five partners in the past 12 months. 39% reported ever meeting a sexual partner at the venue of interview. In univariate analyses, the 14 venues differed significantly by participants' reported age, ethnicity, number of lifetime male partners, past STI infection, HIV+ status, number of HIV+ individuals known, and finding partners at that venue. In multivariable analyses using marginal structural models, after controlling for participants characteristics, venues demonstrated significant structuring of HIV+ status, past STI, and methamphetamine (see Abstract P1-S2.58 figure 1).

Abstract P1-S2.58 Figure 1

Conclusions

We demonstrated significant population structure in demographics, social networks, and HIV and STI status among MSM, which may assist in targeted surveillance and prevention. Interview venue may be associated with HIV, STIs and risk behaviours, separate from commonly collected individual-level data. In order to ensure successful in'terventions, a more thorough mechanistic understanding of how risky venues “emerge is needed.”
P1-S2.62 Factors associated with high-risk penetrative sex in a cohort of treatment experienced HIV-positive men who have sex with men (MSM) in British Columbia
Authors: Michelow W , Talany G , O'Brien N , Wang H , Forrest J , Palmer A , Montaner J S G , Hogg R
Published: July 2011

Background

In Canada, men who have sex with men (MSM) are disproportionately infected with HIV. Despite much evidence demonstrating the secondary preventive value of HAART, we have not fully capitalised on potential synergies between treatment and prevention. This study investigates high-risk sexual behaviour among treatment-experienced MSM in British Columbia, Canada.

Methods

We analysed data from the Longitudinal Investigations into Supportive and Ancillary Health Services (LISA) project on MSM (gay, bisexual, or reported sex with men in the 6 months prior to interview). High-risk sexual behaviour was penetrative anal or vaginal sex in the 6 months prior to interview with less than 100% condom use. Multivariate logistic regression was used to identify factors associated with high-risk penetrative sex.

Results

Of 346 HIV-positive MSM, median age was 46 years, 268 (78%) were currently on HAART, with 185 (54%) having ≥350 CD4 cells/μl. Ninety-eight (28%) participants endorsed seeking out HIV-positive partners for sex, and 147 (43%) reported being less likely to use a condom with an HIV-positive partner. In the regression model, HIV-positive MSM with a CD4 count ≥350 cells/μl were more likely to report unprotected penetrative sex (Adjusted OR [AOR] =2.7; 95% CI 1.5 to 5.2), more likely to not use condoms with their HIV-positive partners (AOR=12.0; 95% CI:6.4 to 22.3), and less likely to report sex with anonymous partners in the past 6 months (AOR=0.28; 95% CI 0.1 to 0.8). No significant associations were found between high-risk penetrative sex and current HAART use, viral suppression, or treatment adherence.

Conclusion

HIV-positive MSM who report engaging in high-risk penetrative sex are more likely to be healthier (higher CD4 counts), to have unprotected sex with other HIV-positive partners (serosorting) and with known rather than anonymous sex partners. Despite healthier MSM reporting more high-risk sex, results suggest this risk-taking is discriminate and would not necessarily lead to more onward HIV transmission.
P1-S2.64 Demographic characteristics and HIV risk behaviours among men who have sex with men in Guatemala City, Guatemala, 2010
Authors: Alvarez B , Miller W , Hernandez F M , Alvarado A , Morales S , Paz-Bailey G
Published: July 2011

Background

In Central America, surveillance of HIV has been strengthened by regular and systematic collection of HIV, sexually transmitted infection, and behavioural data among most at risk populations. In Guatemala, men who have sex with men (MSM) are a highly vulnerable to HIV infection. Behavioural data are needed to help plan for prevention interventions in this group.

Methods

Male residents of Guatemala City at least 18 years of age who self-reported having had anal sex with another man in the past 12 months were invited to participate in a face-to-face structured behavioural survey using respondent-driven-sampling (RDS) from September to December 2010. Participants who provided informed consent were administered a questionnaire that collected information on socio-demographics, risk behaviour, knowledge and attitudes, access to services, and stigma and discrimination, using personal digital assistants (PDA). Medians and IQRs were calculated for continuous variables. Population proportions were calculated for categorical variables and adjusted for RDS-sampling weights using Respondent Driven Sampling Analysis Tool version 6.0.

Results

A total of 500 MSM enrolled in the study. Respondents self-identified as gay or homosexual (39.5%), bisexual (39.5%), heterosexual (11.5%), and transvestite or transgender (9.5%). Median age was 26 years (IQR 22−34 years). The majority of respondents (79.5%) reported to have access to free condoms in the past 12 months. Consistent condom use with all male partners in last 12 months and during last sex was reported by 62.2% and 75.4%, respectively. Overall, 44.3% reported having sex with a woman in the past 12 months. Consistent condom use with female sexual partners in the last 12 months and during last sex was reported by 46.1% and 66.0%, respectively. The median number of female sexual partners reported in the last 12 months was 3 (IQR: 2−5). Ever paying for sex and paying for sex in the last 12 months was reported by 16.0% and 8.3%, respectively; while 54.0% and 44.7% reported ever selling sex and in the last 12 months, respectively. Injection drug use in the last 12 months was reported by 0.8%. Overall, 73.3% of respondents reported ever having an HIV test and 43.1% had been tested in the past 12 months.

Conclusions

MSM in Guatemala engage in high risk behaviours that place them and their male and female partners at high risk for HIV infection. Innovative strategies are needed to promote condom use and access to HIV testing and counselling.
P1-S2.67 Prevalence ofChlamydia trachomatisandNeisseria gonorrhoeaeamong college students who attended the Johns Hopkins University Health and Wellness Center from 2009 to 2010
Authors: Quinn N , Agreda P , Joffe A , Gaydos C
Published: July 2011

Background

The Centers for Disease Control and Prevention (CDC) recommends that sexually active women 25 years or younger be tested yearly forChlamydia trachomatis. An ongoing screening program among college students attending a university gave students the opportunity to be screened forC trachomatis(CT) andNeisseria gonorrhoeae(GC).

Methods

Male and female college students attending Johns Hopkins University were offered screening for chlamydia and gonorrhoea by the Health and Wellness Center. From February 2009 to December 2010, 1114 male urines and female vaginal specimens were submitted to the STD Research Laboratory for CT and GC screening using the Gen-Probe Aptima Combo2 assay. Results were returned to the Johns Hopkins University Student Health and Wellness Center which treated the infected students. 10 students were also tested forTrichomonas vaginalis(TV) with Gen-Probe ATV Analyte Specific Reagent assay (ASR).

Results

As of 31 December 2010, there were 284 (25.5%) males and 830 (75%) females tested, between the ages 17−48 yr. 810 (72.7%) were White, 76 (6.8%), Black, 146 (13.1%). Asian/Pacific Islander, 5 (0.44%) were American Indian, and Other/unknown 78 (7.0%). 71 (6.4%) students were Hispanic and 120 (10.8%) indicated they were symptomatic. The overall prevalence of CT and GC was 1.6% (18/1114) and 0.2% (2/1114), respectively. All TV results were negative. 8/284 (2.8%) males and 10/830 (1.2%) females were CT positive. 5/18(27.8%) were symptomatic (3 females, 2 males) and 7/8 were between 18 and 29 yrs of age (there was one 34 yr. old Black male). Among the 18 CT positive students, 13 were White, 1 Black, 2 Asian/Pacific Islander, 2 were other/unknown; 4 were Hispanic and 14 non-Hispanic. Both GC positive female students were asymptomatic; one was 19, and one was 25 yrs old. Both were non-Hispanic with one being Asian and one White.

Conclusions

This ongoing screening program of male and female students from the Johns Hopkins University Student Health and Wellness Center demonstrated a low prevalence of CT and GC among students, attending the Center. Targeted, innovative screening programs may improve outreach to populations with higher prevalences.
P1-S2.68 Targeted interventions for remote Australians; trends in chlamydia and gonorrhoea notifications in aboriginal and non-indigenous Australians 2005−2009
Authors: Graham S
Published: July 2011

Background

Higher rates of chlamydia and gonorrhoea notifications have been reported in Aboriginal and Torres Strait Islander than non-Indigenous people in Australia since the early 1990s.

Methods

Chlamydia and gonorrhoea notification data from the National Notifiable Disease Surveillance System were analysed by age, sex, remoteness and Aboriginal status in jurisdictions where complete data were available. Population rates and χ2test for trend were calculated using STATA version 10.

Results

In the study period, there were 14 000 (1303 per 100 000) chlamydia notifications in Aboriginal people and 111 947 (242 per 100 000) in non-Indigenous people. In both populations the highest rates were in females aged 15−19, with Aboriginal females reporting a rate four times that of the non-Indigenous females. There was a significant increasing trend in the chlamydia notification rate in Aboriginal people over the 5 years (10%, p-trend p<0.001) and also in non-Indigenous people (59% p-trend p<0.001). Over the 5 years there were 17 336 (964 per 100 000) gonorrhoea notifications in Aboriginal people compared to 14 771 (22 per 100 000) in non-Indigenous people. The highest notification rates were in Aboriginal people aged 15−19 years who lived in very remote areas while in non-Indigenous people the highest notification rates were in males aged 30−39 years. Gonorrhoea notification rates in Aboriginal people over the 5 years decreased over the time period (18%, p-trend p<0.001), but there was no significant trend in non-Indigenous people (19% p-trend p=0.667). Although the rate of gonorrhoea decreased in Aboriginal people the rate was 26 times greater than the rate in non-Indigenous people. The female to male ratio for gonorrhoea of 1.1:1 in Aboriginal people suggests mainly heterosexual transmission, while in non-Indigenous people the female to male ratio was 0.29:1 suggesting predominantly homosexual transmission. The reported rates of gonorrhoea in Aboriginal people resident in very remote areas were 19 times Aboriginal people resident in urban areas.

Conclusion

Chlamydia is a generalised epidemic among both Aboriginal and non-Indigenous peoples. In contrast gonorrhoea is predominantly a disease of Aboriginal people in remote areas and urban gay men. We are undertaking a range of trials in quality improvement interventions with Aboriginal communities to address the continued higher burden of STIs notified among Indigenous people in Australia.
P1-S2.69 Prevalence of HPV infections in Metis and First Nations living in Manitoba, Canada
Authors: Demers A , Shearer B , Totten S , Fang L , Severini A , Kliewer E , Mao Y , Wong T , Jayaraman G
Published: July 2011

Background

Information on human papillomavirus (HPV) prevalence among Aboriginal populations (First Nations, Métis, Inuit) in Canada remains scarce but is needed for informed public health programming. This need is reinforced by the rapidly changing rates of cervical cancer screening in these populations and the introduction of prophylactic vaccines.

Method

In 2008, 52 clinics across the province of Manitoba, Canada participated in a Pap Week initiative during which left over tissues from conventional Pap tests were used for HPV typing using the Luminex method (developed by the National Microbiology Laboratory). A risk-behaviour survey was also administered to consenting women. Chi-square was used to compare frequencies and logistic regression was used to model the data. The most significant factors were included in the multivariate logistic model.

Results

Of 592 women recruited, 113 self-reported being Meti or First Nations (M/FN); 70 did not report their ethnic background and were excluded from the analysis. M/FN participants were younger than the non-M/FN participants (mean age: 39 vs 45, p<0.0001). HPV infection prevalence was 2.3 times higher in M/FN than in other participants (32.7% vs 14.2%, p<0.0001). This increase was mainly due to the higher prevalence of HPV 32, 35, 51, 58, and 62. The prevalence of HPV 16 and 18 in the M/FN population was comparable to that of the non-M/FN (p=0.64), although HPV 18 slightly higher in M/FN (5.6% vs 3.8%). Compared to their non-Aboriginal counterparts, M/FN women participating in the study were more often smokers (p<0.0001), had a higher number of sexual partners in the last year (p=0.0004), and were more often in an unstable relationship (p=0.03). The strongest predictors for HPV infection in the study population were the number of sexual partners over the last year (OR 5.71; 95% CI 3.08 to 10.58) and having reported a M/FN identity (OR 2.17; 95% CI 1.28 to 3.69).

Conclusion

Certain types of HPV may be more prevalent in M/FN than in the non-Aboriginal population. Although it is clear that the HPV vaccine has the potential to lower the prevalence of HPV 6, 11, 16, and 18 infections and related diseases in the M/FN population living in Manitoba, its impact could be mitigated by the relatively high prevalence of other HPV types.
P1-S2.70 The detection and management of pelvic inflammatory disease in aboriginal women in Central Australia: challenges of a remote high prevalence setting
Authors: Silver B , Knox J , Smith K , Ward J , Boyle J , Guy R , Kaldor J , Rumbold A
Published: July 2011

Background

In many remote Aboriginal communities in Australia, the prevalence of gonorrhoea and chlamydia is very high. Client mobility, frequent staff turnover and delays in laboratory results hamper timely treatment. Untreated gonorrhoea and chlamydia can lead to pelvic inflammatory disease (PID). In Central Australia, current remote health guidelines recommend three levels of criteria for diagnosing PID in women with lower abdominal pain: (1) cervical excitation or adnexal tenderness or uterine tenderness; or (2) in the absence of a bimanual examination, vaginal discharge; or (3) in the absence of vaginal discharge in women aged <35 years, intermenstrual bleeding or dyspareunia or a history of STI or PID in the past 12 months. We review adherence to these guidelines in remote primary healthcare centres.

Methods

We conducted a review of medical records of Aboriginal women aged 14−34 years attending five primary healthcare centres in areas with high STI prevalence. Any clinical presentation during 2007−2008 with documented lower abdominal pain after the exclusion of other causes was included. We ascertained if the recommended investigations, diagnosis and treatment were documented, according to the guidelines.

Results

Of the 741 medical records reviewed, there were 224 presentations with lower abdominal pain in 119 women (16%). Of these, a bimanual examination was undertaken in 15 presentations and either cervical excitation, adnexal or uterine tenderness was recorded in eight (Level 1). History taking for vaginal discharge was documented in 59 presentations (26%), and vaginal discharge recorded in 16 (Level 2). History taking for intermenstrual bleeding or dyspareunia was documented in 27 (12%) and 17 (8%) presentations, respectively and recorded in 10 and 3 presentations, respectively (Level 3). From the available records, at least 78 presentations had evidence of a positive STI or PID in the previous year (Level 3). Overall, a PID diagnosis was documented by the remote practitioner in 35 (16%) of the 224 presentations and none had the recommended treatment regime documented.

Conclusion

These results show that most Aboriginal women in remote Central Australia presenting with lower abdominal pain are having inadequate investigations for PID. When a PID diagnosis is made treatment is often inappropriate. Efforts are currently being made to develop electronic diagnosis and management pathways to improve adherence to clinical guidelines.
P1-S2.71 Sexually transmitted infections in Mexico-City's penitentiary centers: the Ponte a Prueba: put yourself to the test “study”
Authors: Bautista S , Fernández-Cerdeño A , Juárez-Figueroa L , González-Rodríguez A , Sierra J , Volkow P
Published: July 2011

Background

Social and behavioural risk factors, as well as the conditions within penitentiary centers, place incarcerated people at high risk for infectious diseases. Few data exist for penitentiary health in Latin America and even fewer outside the context of small sample size studies, usually focused on a single one disease or infection. Our study aimed to probe Mexico City's inmates' health status and relevant, associated Behaviours with focus on HIV and other sexually transmitted infections (STI).

Methods

A cross-sectional health survey was implemented in three penitentiary centers for male and two for female detainees, between May and September 2010. All inmates were offered voluntary HIV, Hepatitis C (HCV), Hepatitis B (HBV) and Syphilis tests, along with screening for metabolic disorders. Informed consent and usable blood samples were obtained from 78% of males (15 835/20 688) and 92% of females (1757/ 1914). A random sample of participants answered a risk-factor questionnaire. The institutional review board (IRB) at Mexico's National Institute of Public Health approved study methods. Data analysis was performed using SPSS 16.

Results

HIV prevalence was 0.7%, irregardless of sex. For HCV, we found 3.3% and 2.7% for men and women, respectively. HBV antibodies were found in 3.0% of men (of which 5% had positive surface antigen (sAg+)) and 3.2% of women (of which 9% of had sAg+). Of men, 3.6% had antitreponemic antibodies for syphilis (half of these were untreated). Among women 8.8% ever had syphilis, just over a third of these (36%) untreated. Lifetime marijuana use was 48.7% and 29.6% for men and women, respectively; 38.44% and 27.4% ever used cocaine; 5.2% and 3.5% ever injected drugs; 2.2 and 1.1 ever used heroine; 32.9% of men and 25.7% of women reported sex in prison, 75% of both genders declared unprotected last coitus.

Conclusion

Despite the challenges in penitentiary centers of middle-income countries, ethical testing for HIV and STIs proved feasible and acceptable. All diagnosed individuals are now receiving the follow-up or treatment they need. HIV and other STI rates were low compared with prisons in other countries but higher than the general population in Mexico. Our study provides baseline data which can be used to design and evaluate prevention strategies within the prison system.
P1-S3.05 Attributable proportion of tubal factor infertility caused by chlamydia: an estimate based on serological evidence adjusted for test resolution
Authors: Price M , Ades A E , Macleod J , Horner P
Published: July 2011

Background

Many published studies compare the prevalence ofChlamydia trachomatis(CT) antibody in women with Tubal Factor Infertility (TFI) and a control group. In principle these studies can be used to estimate the attributable fraction of TFI caused by CT, however it is necessary to account for the sensitivity and specificity of the antibody tests employed.

Methods

We use sensitivity and specificity estimates from a discrepancy analysis by Morre (2002), and a study by Wills (2009) in which specificity of antibody test results was assessed in children, to derive estimates of the resolving power of three peptide-based assays and MIF; this is a reflection of the difference between sensitivity and false positive rates. Based on studies of antibody levels in different settings we adopt a model which assumes that antibody levels in women whose TFI is caused by CT are higher than levels in control women or those whose TFI has other causes. Applying this model to the data from Land (2003) we find strong support for the hypothesis of higher antibody levels in CT-related TFI, and for the estimates of test resolution from earlier studies. Using a range of assumptions about cumulative incidence of CT in the control group we were able to derive a range of estimates for the proportion of TFI cases caused by CT.

Results

Our results suggest that the sensitivity of antibody tests in women whose TFI was caused by CT is higher than in women who have previously had CT but whose TFI was due to another cause and control women. Based on our estimates of the resolving power of the tests from the Morre (2002) and Wills (2009) studies we estimate the proportion of TFI episodes that are due to Chlamydia to be between 20% and 45%. Conclusions By adjusting for the sensitivity and specificity of tests it is possible to derive a quantitative estimate of the causal rate of CT in TFI. Taken together with other findings our results suggests that detailed studies of antibody levels can be used to shed further light on the causal rate of CT.
P1-S4.06 What impact does missing Quebec data have on national HIV surveillance data?
Authors: Tomas K L , Bitera R , Alary M , Fauvel M , Parent R , Sylvain D , Hastie M , Claessens C , Halverson J , Archibald C
Published: July 2011

Objective

To quantify the difference in the exposure category breakdowns of national HIV surveillance figures if exposure data from the Institut nationale de Santé Publique du Québec (INSPQ) were included in national datasets.

Background

National HIV/AIDS surveillance is coordinated by the Public Health Agency of Canada's (PHAC) Surveillance and Risk Assessment Division's (SRAD). HIV is reportable in all provinces and territories, although the degree of epidemiologic information collected and submitted varies. Quebec's case reports to PHAC come from their laboratory-based surveillance system, which contains positive test reports, by age and sex. All Quebec cases are classified in SRAD's dataset as Not Reported, which contributes to the large proportion of cases at the national level with no known exposure category.

Methods

Quebec's provincial HIV surveillance system “Programme de surveillance de l'infection par le VIH au Québec” collects further epidemiological information, including exposure category and risk factor information, although recorded separately from the HIV laboratory test results file. This provincial system's exposure category data was added to existing national surveillance data, and the exposure category breakdowns recalculated, in order to assess change in the proportion of unknown/not reported cases and to quantify the resulting difference in exposure category breakdowns at the national level.

Results

With inclusion of Quebec data for 2009, there is a 50% decrease (from 45.5% to 23.1%) in the proportion of national HIV cases with unknown exposure category. There are also differences in the overall national exposure category breakdowns. For 2009, proportional increases were observed in the men who have sex with men (MSM) and heterosexual-endemic categories (5.4% and 2.8% respectively), while proportional decreases were observed in the exposure categories of injection drug use (−4.1%), heterosexual-risk (−2.0%), and no-identified-risk heterosexual (−2.2%).

Conclusions

Inclusion of Quebec's risk exposure data in the national HIV dataset is significant; the national dataset becomes more complete and the proportion of cases with unknown exposure category is reduced. This analysis demonstrates that inclusion of exposure category data, from the provincial HIV surveillance system of Quebec's INSPQ can alter the exposure category breakdowns at the national level, thereby offering a more accurate picture of HIV diagnoses in Canada.
P1-S4.08 Population size estimates for men who have sex with men in Guatemala City using time location sampling and respondent driven sampling
Authors: Paz-Bailey G , Alvarez B , Miller W , Sabrina B , Barrington C , Kim A , Morales S , Chen S
Published: July 2011

Background

Men who have sex with men (MSM) are highly vulnerable to HIV infection, but this population can be particularly difficult to reach in Central America due to stigma and violence. Knowing the size of populations at high risk for HIV and sexually transmitted infections (STI) is critical for informing prevention, care, and treatment programs. Simple approaches are needed to provide baseline estimates of the population size of MSM in Guatemala to advocate for appropriate resource allocation and programming. We compared population size estimates of MSM and transgender persons using capture-recapture linked to two differentsurveys that were developed concurrently using different sampling methodologies.

Methods

Capture recapture methods for estimating population size were integrated into two probability-based surveys using respondent driven sampling (RDS) and time-location sampling (TLS); conducted simultaneously among MSM in Guatemala City from October to December 2010. Key chains were used as uUnique objects in the form ofand study key chains were distributed approximately 1-month prior to the surveys in venues known to be frequented by MSM. Duplicate participation was avoided by using the same team to distribute the key chains and administering a set of questions before handing the object. Participants in the RDS and TLS surveys were asked, as part of the study interview, whether they had received the key chain. We assigned the number of key chains distributed in venues as the first capture and the proportion of participants that reported receiving the key chain in the RDS or TLS survey as the second capture. By applying standardised formulas for estimating population size using capture-recapture methods, we estimated the number of MSM in Guatemala City and 95% CIs around this estimate, adjusted for RDS and TLS sampling design.

Results

A total of 2128 key chains were distributed in the first capture. Of the 501 MSM interviewed in the RDS survey, 200 (RDS adjusted, 23.4%) had received the key chain. Thus the RDS adjusted estimated population size of MSM in Guatemala City was 9,190 (95% CI 7765 to 10 616). Of the 504 MSM interviewed in the TLS survey, 193 (TLS adjusted, 32.1%) had received the key chain. The TLS adjusted estimated number of MSM was 6620 (95% CI 5813 to 7427).

Conclusions

Estimates of MSM population size using the TLS survey resulted in a significantly lower estimate than that obtained through RDS survey, probably due to the fact that TLS targets MSM who attend venues. The estimate obtained through RDS may better reflect the size of the larger MSM population in Guatemala City, since this itRDS reaches MSM attending and not attending publicmeeting venues. Integrating capture-recapture methods in probability-based surveys among MSM is a simple and fast approach for providing the population sizes needed to inform and evaluate programs for MSM in Guatemala.
P1-S4.13 Mapping high risk activities of HIV/AIDS in Gaoxin and Yantan District of Zigong City
Authors: Zhang J , Yang Y , Zhou H , Yang C , Li Q , Song G , Xie Y , Blanchard J , Yu N , Ma X
Published: July 2011

Background

Zigong is located in the south of Sichuan Province of China. As a key area with a large number of migrants, Zigong has long been confronting the danger of HIV/AIDS. The goal of “Zigong geographic mapping on HIV/AIDS high-risk population” research project is to provide information on the location, type and volume of the female sex workers (FSWs) in Gaoxin (urban) and Yantan District (rural) to provide baseline information for HIV/AIDS prevention policy and programs in future.

Methods

This study adopted a “geographical approach” to map the location and spots of the activities of sex trade and estimated the number of FSWs involved in the activities. This included two sequential steps: 1) Systematic information gathering from key informants (KI) suggested the locations (“hot spots”) where FSWs congregate. 2) The “hot spots” were validated through site visit and insiders; the information about the number and characteristics of FSWs in each spot were collected.

Results

In Gaoxin District: 59 high-risk spots were confirmed and 16 clusters were marked in 10 zones. The most common type of sex trade spots was hair salon/massage room/foot massage room. 72.9% of the spots were both “seeking risk” and “taking risk”, while 22.0% and 3.4% were only “seeking risk” and “taking risk” respectively. 39.0% of the spots had more than three clients per FSW per day. The estimated number of total FSWs in this urban area was 303. 38.5% of FSWs were in hotel/small lodge, while 29.3% and 27.3% were in small tea house/bar/KTV and hair salon/massage room/foot massage room respectively. The peak season, peak date and peak time of the most spots was summer, the whole week, afternoon and night. In Yantan District: 12 high-risk spots were confirmed and half were concentrated in Yantan Town. The most common type was small tea house/bar/KTV. Nine spots were both “seeking risk” and “taking risk”, while three were “taking risk” only. Five spots had more than three clients per day for each FSW. The estimated number of FSWs was 42, and 74.4% worked in the small tea house/bar/KTV. The peak season, peak date and peak time of the most spots was spring and summer, the whole week, and night, respectively.

Conclusions

The mapping approach provided direct and visible geographic distribution information, which enables a quick mastery of the distribution of high risk spots and the number of high risk population, for public health intervention planning and program implementation.
P1-S4.14 Does core theory apply in rural environments?
Authors: Gesink D , Sullivan A , Norwood T , Serre M , Miller W
Published: July 2011

Background

The expansion of core theory to include geographically defined core areas of elevated infection has been based primarily on spatial investigations into sexually transmitted infections (STIs) in large urban areas. It is uncertain whether core theory is applicable for rural environments. Our objective was to evaluate the concept of geographical core areas for gonorrhoea and syphilis in North Carolina, a rural state with urban pockets.

Methods

We analysed geomasked gonorrhoea and syphilis cases reported to the North Carolina State Health Department's sexually transmitted disease surveillance program from 1 January 2005 to 31 December 2007 for gonorrhoea and from 1 January 2000 to 31 December 2007 for syphilis. Incident gonorrhoea and syphilis rates were estimated using census tract level population estimates for the total North Carolina population from the US census. Rates were mapped by census tract and quarter. Rurality was measured at the census tract using two different definitions: percent rural and rural-urban commuting area (RUCA). RUCAs were used to classify North Carolina census tracts into rural, small town, micropolitan, or urban. SatScan was used to identify spatiotemporal clusters of significantly elevated rates of infection. Clusters were classified as outbreak or core based on duration. Clusters lasting the entire study period were considered potential core areas, while clusters of shorter duration were considered outbreak areas. Clusters were overlaid on maps of rurality and qualitatively assessed for correlation.

Results

On average, gonorrhoea rates are low in the western mountains and higher in the eastern coastal part of the state. Most of the clusters were located in urban RUCAs or very low percent rural. Clusters for rural and small town RUCAs were of short duration and usually covered several census tracts and sometimes more than one county. Consequently, they were considered outbreak areas rather than core areas. Similar results were found for syphilis.

Conclusions

We found that core areas of elevated STIs were limited to the urban centers in rural environments. Significant clusters of infection in rural environments appear to be due to outbreaks. Rural environments may have core areas but not enough infection to sustain ongoing transmission. Bridge contacts may be more important for STI transmission in rural environments.
P1-S1.16 Estimating HIV incidence rate among stable sexual partnerships in sub-Saharan Africa
Authors: Chemaitelly H , Abu-Raddad L J
Published: July 2011

Background

Empirical evidence suggests that HIV incidence rate within stable discordant sexual partnerships in sub-Saharan Africa (SSA) varies between 1.2 and 19.0 per 100 person-years. Estimating HIV incidence rate within stable discordant partnerships is critical for determining the contribution of HIV sero-conversions among these partnerships to total HIV incidence.

Methods

We constructed a mathematical model based on competing-hazards formalism to estimate HIV incidence rate within stable discordant partnerships across 20 countries in SSA. We also used the model to analyse the patterns of HIV discordancy in SSA. The model was parameterised using Demographic Health Survey data and analyses were conducted at endemic equilibrium. Sensitivity analyses were performed to explore the dependence on the dynamical drivers of discordancy.

Results

Our model fitted well the empirical epidemiological measures of HIV discordancy and yielded an estimate for HIV incidence rate among discordant partnerships of 11.2 per 100 person-years (95% CI 8.9 to 13.4 per 100 person-years). HIV incidence rate ranged between 5.5 and 17.2 per 100 person-years across the countries. We also identified HIV incidence rate within stable discordant partnerships and HIV incidence rate from sources external to the partnership (or equivalently HIV prevalence) as key determinants of the variability in discordancy measures across SSA.

Conclusions

Our estimate for the HIV incidence rate among discordant partnerships agrees well and falls in the mid-range of empirical estimates for this measure. There is however considerable variability across the countries. Biological and behavioural factors including differences in transmission rates such as due to male circumcision, may have contributed to the variability in HIV incidence rates among discordant partnerships across SSA. More research is needed to elucidate the determinants of this variability in incidence rates.
P1-S4.20 Mathematical modelling of HIV transmission and control among men who have sex with men: a review of 25 years of literature
Authors: Punyacharoensin N , Edmunds W J , De Angelis D , White R Guy
Published: July 2011

Background

For a quarter of century, mathematical models have been used to study the spread and control of HIV among men who have sex with men (MSM). We reviewed this literature to summarise the methodologies used, key model developments, and recommended strategies for HIV control among MSM.

Methods

Review of the literature on dynamic compartmental models of HIV transmission among MSM was conducted. MEDLINE/EMBASE were searched from earliest date to end 2010.

Results

Of 742 studies identified, 127 studies met the inclusion criteria and were selected for review. Most studies employed deterministic methods (80%), and potentially as a result of this, as the complexity of models increased over time with respect to antiretroviral therapy (ART), there was a marked decline in the complexity of models with respect to sexual activity. Only a small proportion of models were fitted to data (22%) and even fewer were validated (17%), somewhat reducing confidence in the findings from these studies. That said, a number of common findings emerged, including (1) the importance of assumed changes in infectivity and sexual contact rates on the impact of ART on HIV incidence, and that this led to follow-up empirical studies to gather these data, and (2) the recommendation that multiple strategies would be required for effective HIV control among MSM.

Conclusions

Mathematical models have been useful in indentifying key empirical studies and for showing that multiple prevention strategies would be required for effective control of HIV epidemics in MSM. The lack of model fitting and validation emphasise that this area should be targeted for developments in the future. An improved methodology for parameter estimation will help generate predictions that more fully express uncertainty, allowing more informed public heath decision making.
P1-S4.23 Describing the progression fromChlamydia trachomatisto pelvic inflammatory disease: systematic review of mathematical models
Authors: Herzog S A , Heijne J C M , Althaus C L , Low N
Published: July 2011

Background

Chlamydia trachomatis(chlamydia) is an important cause of pelvic inflammatory disease (PID). Preventing PID is a main objective of chlamydia screening. There are many uncertainties about how and when bacteria spread from lower to upper genital tract. The potential impact of screening and treatment, which could interrupt ascending infection, might be affected by the timing of development of PID. Models are often used to investigate the potential impact of screening strategies on PID and should therefore include information about the timing of progression. We conducted a systematic review to determine how the progression from chlamydia to PID is described in mathematical models.

Methods

We searched four electronic databases using search terms related to mathematical models and PID from the earliest date to 19 October 2009 without language restrictions. Eligible publications included progression from chlamydia to PID either using a decision tree or a mathematical model. We extracted information about how authors conceptualised the dynamics of chlamydia infection and the development of PID, and assumptions about rates of progression.

Results

We identified 41 unique publications about chlamydia infection; 28 of these included PID in a static decision tree. The average percentage of women developing PID in decision analyses was 22.9% (range 10–35%, n=26). For five publications it was not clear how the described model worked. The other eight publications described progression from chlamydia infection to PID dynamically. Of these, two models incorporated PID as a state in a Markov-chain model, four used compartmental models and two used individual-based models. Explicit statements about model structure included the possibility that PID can occur uniformly during a woman's infection, that tubal damage occurs in the second half of the chlamydia infection, and that the model had the ability to vary PID development time. Twenty-eight publications did not mention the stage during a chlamydia infection that progression to PID happens.

Conclusion

Most modelling studies do not consider dynamic aspects ofC trachomatistransmission and the timing of progression to PID. The mechanisms proposed in studies that made explicit statements could be compared to examine the impact of screening. We suggest that explicit statements about the timing and rates of progression would help improve understanding of the pathogenesis of chlamydial complications and the potential effects of screening.