Prevalence and correlates of HIV infection and sexually transmitted infections in female sex workers (FSWs) in Shanghai, China.

In 2009, we examined HIV and sexually transmitted infections (STIs) in 750 female sex workers (FSWs) in Shanghai using a cross-sectional survey. Participants (mean age 27 years) were interviewed and tested for HIV and selected STIs. Prevalence was: HIV 0·13%, chlamydia 14·7%, gonorrhoea 3·5% and syphilis 1·3%. In a demographic multivariate model, younger age, higher income and originating from provinces other than Zhejiang and Shanghai were independently associated with STI. In a social and sexual behavioural model, women working in small venues with fewer clients per week, use of drugs, and higher price charged per sex act indicated a greater risk for STI. Although HIV appears rare in Shanghai FSWs, chlamydial infection is common, especially in women aged <25 years (prevalence 19·6%). Since STI and HIV share similar risk factors, preventive intervention measures should be implemented immediately based on the venues and characteristics of FSWs to prevent future spread of HIV.

Correlates of unprotected anal sex at last sexual episode: analysis from a surveillance study of men who have sex with men in Montreal.

Recent increases in rates of unprotected anal sex (UAS) among men who have sex with men (MSM) signal the need to continually refine our understanding of factors associated with risky sexual behavior. Data were collected using a questionnaire eliciting information about the last sexual episode (LSE) with another man in the past 6 months. Logistic regression was used to identify both event-level and background correlates of UAS at LSE. 965 participants who reported having sex with a partner with whom they were not in a couple relationship at LSE were studied. Several event-level variables were significantly associated with UAS after adjusting for background factors, including finding the partner at LSE sexually attractive and using alcohol or cocaine at LSE. Our findings parallel the results of other HIV prevention studies which have highlighted the importance of interpersonal factors that influence risk-taking at the moment of a sexual act among MSM.

Migration and HIV: an epidemiological study of Montrealers of Haitian origin.

We aimed to determine the prevalence of HIV infection and associated risk factors among Montrealers of Haitian origin. We carried out a voluntary, anonymous survey in 7 primary care medical clinics in Montreal among 5039 persons aged 15 to 49 years born in Haiti or with at least one parent born in Haiti. The participation rate was 94.3%. Overall, HIV prevalence was 1.3% (1.6% in men and 1.1% in women). The HIV prevalence was lower among those born in Canada or who had resided in Canada longer. The prevalence among subjects who had travelled to Haiti in the previous 5 years was 2.0%, twice the rate of those who had not. The adjusted population attributable fraction of HIV infections associated with having had unprotected sex in Haiti was 10.2%. This study identified risk factors which will help in the design of more effective prevention programmes among Montrealers of Haitian origin.

The epidemiology of HIV and AIDS in Canada: current perspectives and future needs.

There is little doubt the HIV epidemic is of enormous public health importance for Canadians. Currently, it is estimated that between one and two in 1,000 adult Canadians are infected with HIV. Compared to other industrialized countries, Canada is a country of intermediate incidence. Much effort has gone into developing and maintaining the AIDS surveillance system as well as carrying out HIV seroprevalence studies in selected populations. In spite of under-reporting of AIDS cases (estimated to be 12-25%), the available data provide a general picture of the HIV epidemic in Canada. Nevertheless, a number of questions remain unanswered, and we need more information to plan preventive interventions and provide services to persons who are already infected. In this article, we present a brief overview of the epidemiology of AIDS and HIV in Canada. We identify some disturbing trends in the epidemic and reiterate the need for more information to improve our preventive efforts and help set research priorities to help plan future studies.

Screening for HBsAg in pregnant women: a cost analysis of the universal screening policy in the province of Quebec.

We carried out a cost analysis of a universal prenatal screening policy for hepatitis B virus infection in pregnant women. A universal screening policy in the province of Quebec (87,000 births per year) would cost about $473,000 per year and the prevention of one chronic carrier, $8,915. The cost varied greatly according to the ethnic origin of the mother and the cost of the serologic test. Strategies to reduce the cost of the serologic test could greatly reduce the cost of this screening policy.

Risk factors for measles and vaccine efficacy during an epidemic in Montreal.

OBJECTIVES: 1) to identify potential risk factors for measles and 2) to assess the efficacy of the measles vaccine. METHODS: Cases of measles reported from primary and secondary schools in Montreal during the 1989 epidemic were compared with classroom and sibling controls with respect to age at vaccination against measles, time since vaccination, type of vaccination, type of providers and age of the mother. RESULTS: Subjects vaccinated at 12 months had an OR of 3.9 (CI 95%: 2.1 to 7.0) of contracting measles when compared with subjects vaccinated at 15 months or later. Vaccination at age 13 or 14 months was not associated with an increased risk. Subjects vaccinated before June 1979 had an OR of 5.8 (CI 95%: 2.8 to 12.1) of developing measles compared with subjects vaccinated after June 1980. Vaccine efficacy was 96.1%. DISCUSSION: In highly vaccinated populations, vaccination at 12 months and vaccination before 1980 are probably two reasons why outbreaks still occur. The two-dose schedule could reduce the proportion of vaccinated persons who remain susceptible.

Improved disease reporting: a randomized trial of physicians.

OBJECTIVES: To determine if a heightened, passive surveillance system increases the number of physicians reporting two notifiable diseases during a six-month period. METHODS: We conducted a randomized trail among 145 community-based primary care physicians in two counties in Eastern Ontario. Intervention group physicians received a three-part intervention aimed at improving their communication with the health unit to whom all physicians are mandated to report notifiable diseases. The control group physicians remained part of the usual disease reporting system. The outcome was assessed by a relative risk comparing the number of physicians reporting among the intervention group to that in the control group. RESULTS: Seventy physicians received the intervention and 75 physicians were in the control group. The relative risk for the number of physicians reporting at least one case was 5.9 (95% CI 2.6-13.2). CONCLUSIONS: The intervention had an impact on reporting of notifiable diseases by physicians.

Risk behaviours and HIV infection among men having sexual relations with men: baseline characteristics of participants in the Omega Cohort Study, Montreal, Quebec, Canada.

OBJECTIVE: To describe characteristics of men having sex with men (MSM) participating in the Omega Cohort, to describe HIV-positive participants at baseline interview, and to estimate HIV incidence. METHODS: The Omega Cohort is a study on the incidence and psychosocial determinants of HIV infection among MSM living in Montreal. MSM complete a questionnaire and are tested for HIV every six months. RESULTS: During the previous six months, 31% and 12% of 810 participants (mean age = 33 years) reported unprotected anal sex with regular and casual partners, respectively. Eight participants (0.98%) were HIV-infected at baseline. HIV incidence was 0.89 per 100 person-years (7/787 person-years) [95% confidence interval: 0.36-1.83]. CONCLUSION: A significant proportion of participants reported current risk behaviours. Despite this, HIV incidence is relatively low. It is important to target MSM who do not practice safe sex and to encourage those practicing safe sex to sustain these behaviours.

Characterizing viral subtypes to assess patterns of HIV transmission.

We characterized HIV-1 subtypes among 204 persons newly diagnosed with HIV in Ontario from 2003 to 2005 using samples from the Canadian HIV Strain and Drug Resistance Surveillance Program. We examined HIV-1 subtype by demographic characteristics and exposure category, and determined independent predictors of infection with a non-B HIV subtype using multivariate logistic regression. The distribution of HIV subtypes was: B 77.0%, C 10.3%, AG 4.9%, A 2.5%, AE 2.5% and others 3.0%. Overall, 23.0% were non-B, greater in women than in men (62.8% versus 12.4%, P < 0.0001) and persons under 35 years (31.1% versus 18.5% in those ≥35, P = 0.04). Non-B subtype was predominant (78.9%) among persons from HIV-endemic regions and considerable (28.6%) among other persons infected heterosexually. In multivariate modelling adjusted for gender, non-B subtype was significantly associated with birth in an HIV-endemic region (adjusted odds ratio [aOR] 59.2, P < 0.0001) and heterosexual exposure (aOR 6.3, P = 0.02). Additionally, compared with men who had sex with men, non-B subtype was greater among heterosexual women (aOR 17.8, P < 0.001) and women who injected drugs (injection drug use, aOR 13.4, P = 0.01). We found a non-negligible proportion of non-B subtypes among women infected heterosexually not from HIV-endemic countries, providing interesting insights into HIV transmission patterns.

Mother-to-child transmission of GB virus C in a cohort of women coinfected with GB virus C and HIV in Bangkok, Thailand.

BACKGROUND: GB virus C (GBV-C) is an apathogenic virus that inhibits human immunodeficiency virus (HIV) replication in vitro. Mother-to-child transmission (MTCT) of GBV-C has been observed in multiple small studies. Our study examined the rate and correlates of MTCT of GBV-C in a large cohort of GBV-C-HIV-coinfected pregnant women in Thailand. METHODS: Maternal delivery plasma specimens from 245 GBV-C-HIV-infected women and specimens from their infants at 4 or 6 months of age were tested for GBV-C RNA. Associations with MTCT of GBV-C were examined using logistic regression. RESULTS: One hundred one (41%) of 245 infants acquired GBV-C infection. MTCT of GBV-C was independently associated with maternal antiretroviral therapy (adjusted odds ratio [AOR], 5.21 [95% confidence interval {CI}, 2.12-12.81]), infant HIV infection (AOR, 0.05 [95% CI, 0.01-0.26]), maternal GBV-C load (8.0 log(10) copies/mL: AOR, 86.77 [95% CI, 15.27-481.70]; 7.0-7.9 log(10) copies/mL: AOR, 45.62 [95% CI, 8.41-247.51]; 5.0-6.9 log(10) copies/mL: AOR, 9.07 [95% CI, 1.85-44.33]: reference, <5 log(10) viral copies/mL), and caesarean delivery (AOR, 0.26 [95% CI, 0.12-0.59]). CONCLUSIONS: Associations with maternal GBV-C load and mode of delivery suggest transmission during pregnancy and delivery. Despite mode of delivery being a common risk factor for virus transmission, GBV-C and HIV were rarely cotransmitted. The mechanisms by which maternal receipt of antiretroviral therapy might increase MTCT of GBV-C are unknown.

HIV and ethnicity in Canada: is the HIV risk-taking behaviour of young foreign-born MSM similar to Canadian born MSM?

There is a dearth of information on the HIV risk-taking behaviour of foreign-born men who have sex with men (MSM) in Canada. This study focused on identifying sexual risk behaviour among MSM who immigrated to Canada and compared them to MSM who were born in Canada. Baseline data from the Omega Cohort in Montreal and the Vanguard Project in Vancouver were combined to form four ethnicity/race analytical categories (n = 1,148): White born in Canada (WBIC), White born outside of Canada, non-White born in Canada (NBIC) and non-White born outside of Canada (NBOC). Psychological, demographic and sexual behaviour characteristics of the groups were similar except: NBOC were more likely to be unemployed, less likely to be tattooed, had fewer bisexual experiences and less likely worried of insufficient funds. WBOC were more likely to report unprotected sex with seropositives and more likely to have had unprotected sex while travelling. NBIC were more likely to have ever sold sex and to have had body piercing. WBOC are at high risk of acquiring as well as transmitting HIV. It is important to consider place of birth in addition to ethnicity when developing programmes to prevent the transmission of HIV.

Incidence of tuberculosis among reported AIDS cases in Quebec from 1979 to 1996.

BACKGROUND: The impact of HIV infection on tuberculosis (TB) rates in Quebec has not been fully established. Because concurrent HIV infection is the single most important factor in TB reactivation, the authors used Quebec AIDS surveillance data to quantify the extent of TB among reported AIDS cases and to identify the characteristics of AIDS patients with TB. METHODS: The study population comprised people aged 15 years and over with AIDS diagnosed between Jan. 1, 1979, and Dec. 31, 1996, and reported by Mar. 13, 1997. Patients with TB (all forms) and those without TB were compared. Multivariate logistic regression analysis was used to examine the independent effect of each variable on the AIDS-TB cases. The authors also compared the number of AIDS-TB cases with the number of TB cases to estimate the effect of HIV infection on TB incidence. RESULTS: Of the 4684 people with AIDS reported in Quebec, 242 (5.2%) had active TB at some point during the course of their illness. During 1992-1995, 9.6% of the people with TB in Montreal, and 5.8% in the province of Quebec, also had HIV infection. Those with AIDS and TB were predominantly male (75.2%), manual workers (40.1%) and residents of Montreal (86.4%) and were born in an HIV-endemic country (63.8%). The multivariate analysis indicated that AIDS patients who were born in HIV-endemic countries in the Caribbean, sub-Saharan Africa or other developing regions were 21.8 times (95% confidence interval [CI] 19.5-28.5), 17.9 times (95% CI 12.7-27.1) and 4.9 times (95% CI 3.5-7.0) more likely to have TB than those born in Canada; manual workers and unemployed people with AIDS were 1.6 times (95% CI 1.3-2.0) and 2.0 times (95% CI 1.5-2.6) more likely to have TB than professional workers; and people who acquired HIV infection through heterosexual contact were 2.1 times (95% CI 1.6-3.1) more likely to have TB than men who acquired it through sexual contact with other men. INTERPRETATION: AIDS seems to contribute significantly to the number of TB cases. The results of this study reinforce the importance of offering HIV testing to people in high-risk groups, such as those born in a country where HIV and TB is endemic.

Hepatitis B infection in a day school for mentally retarded students: transmission from students to staff.

We carried out a seroepidemiologic study to evaluate the transmission of hepatitis B virus (HBV) from students to staff in a day school for mentally retarded students. Of 505 students tested, 37 (7.3 per cent) had HBsAg; 74 per cent of HBsAg-positive sera tested were HBeAg-positive. Of 162 staff members tested, 21 (13.0 per cent) were HBV marker positive and two (1.2 per cent) had HBsAg; specialized educators and teachers showed the highest HBV marker prevalence (22.2 per cent and 21.3 per cent, respectively). The prevalence of HBV markers among staff was independently associated with classroom contact with a HBsAg-positive student, duration of employment at the school, and previous work with mentally retarded individuals. The incidence of HBV infection among teaching staff with regular classroom contact, estimated by logistic regression analysis, was 2.6 per cent per year. This observation indicates that teaching staff in schools for mentally retarded students with direct classroom contact may carry an occupational risk of HBV infection.

Risk of HIV infection from blood transfusion in Montreal.

OBJECTIVES: To determine the incidence (including associated donor characteristics and time trends) of HIV infection among repeat blood donors and to estimate the risk of HIV transmission from blood transfusion in Montreal and in Canada as a whole. DESIGN: Retrospective cohort analysis. SETTING: Montreal Centre Blood Transfusion Service. PARTICIPANTS: People who donated blood at least twice after Nov. 1, 1985, and at least once from Apr. 1, 1989, to Mar. 31, 1993. INTERVENTION: Blood was screened for HIV by enzyme-linked immunosorbent assay and results were confirmed by Western blot analysis. OUTCOME MEASURES: Incidence density (the incidence rate per person-time) of HIV infection among repeat blood donors by sex, age group and region of residence, and incidence density and risk among first-time donors and for Canada as whole. RESULTS: There were 200,196 eligible donors and 432,631 person-years (PY) of observation. From 1989 to 1993, there were 18 HIV seroconversions among repeat donors. The crude incidence density was 3.3 per 100,000 PY (95% confidence interval [CI] 1.8 to 5.4 per 100,000 PY); it was 4.9 per 100,000 PY among men and 0.61 per 100,000 PY among women. Age-specific incidence per 100,000 PY was 2.5 among those 12-29 years of age, 5.1 among those 30-49, 2.9 among those 40-49, and 1.4 among those 50 and older. Based on an estimated mean "window period" (from when a donor's blood is capable of transmitting HIV until detectable antibody appears) of 25 days, the current risk of HIV infection from repeat donors in the window period is estimated at 1 in 440,000. Inclusion of blood units from first-time donors produces an overall risk of 1 in 390,000 (95% CI 1 in 250,000 to 655,000). The estimated risk per blood unit in Canada as a whole is 1 in 913000 (95% CI 1 in 507,000 to 2,050,000). CONCLUSIONS: This "sentinel" population of repeat blood donors is subject to important trends in HIV spread. Therefore, estimating the incidence density of HIV infection in repeat donors provides insight into the epidemiologic characteristics of HIV infection at minimal expense. As a result of measures to improve blood safety, including HIV testing, the incidence of HIV infection among blood donors in Canada is low and the risk of HIV transmission from transfusion is extremely small, although not zero.

The risks and benefits of accepting men who have had sex with men as blood donors.

BACKGROUND: It has been suggested that men who have had sex with men (MSM) should become eligible to donate blood if they recently abstained from male-to-male sex. STUDY DESIGN AND METHODS: The impact of a 12-month deferral policy for MSM on the risk of introducing contaminated units in the blood supply and the benefit of obtaining additional donations were estimated. Considered were the prevalence of HIV among MSM, the window period of infection, the rate of laboratory testing errors, and the occurrence of other system failures. This was compared with the risk and benefit that currently results from accepting female donors who have had sex with MSM. RESULTS: The revised policy for MSM would potentially result in one HIV-contaminated unit for every 136,000 additional donations (95% CI, 1 in 69,000 to 1 in 268,000), for an overall increase in HIV risk estimated at 8 percent. The number of donations would increase by 1.3 percent (95% CI, 0.9%-1.7%). The risk-benefit ratio of currently accepting female partners of MSM is approximately five times lower. CONCLUSION: The risk increment of accepting 12-month abstinent MSM would be very small but not zero. From a risk-benefit perspective, the current deferral policy for MSM is more efficient compared to an analogous hypothetical criterion for female partners of MSM.

Enough sterile syringes to prevent HIV transmission among injection drug users in Montreal?

The HIV epidemic among injection drugs users in Montreal continues unabated. We wished to know whether sufficient syringes were being distributed to provide for the needs of injection drug users (IDUs) in Montreal. Using data from several sources, including the estimated number of active IDUs in 1994 and the injection frequency according to the drug consumed, we calculated the number of syringes required by IDUs. The number of syringes estimated was compared with the number of syringes distributed by needle exchange programs or sold in private pharmacies. Overall, we estimated that in 1994 about 10,683,000 syringes were required by the 10,000 IDUs in Montreal. Because about 338,000 syringes were distributed, <5% of the need was being met. The parameters in our analysis, particularly the number of IDUs in Montreal, drug use, and the frequency of injection, are subject to uncertainty. Nevertheless, because of the disparity between the small proportion of syringes distributed and the number required, it is unlikely that sufficient syringes are available to ensure access to clean needles and prevent HIV transmission. Measures should be taken to expand syringe distribution to Montreal IDUs.

Increasing drug resistance of Mycobacterium tuberculosis isolates in Ontario, Canada, 1987-1998.

We examined trends in resistance to first-line antituberculous agents for Mycobacterium tuberculosis strains isolated in Ontario, Canada from 1987 through 1998 (n=8069). The proportions resistant were as follows: isoniazid, 9.6%; rifampin, 1.9%; streptomycin, 4. 9%; ethambutol, 1.3%; and pyrazinamide, 1.7%. Resistance to isoniazid has increased markedly since 1990, whereas resistance to streptomycin, ethambutol, and pyrazinamide increased from 1997 through 1998. Resistance to both isoniazid and rifampin did not increase. The incidence of persistence and reactivation (early or late treatment failure) was 1-2 per 100 person-years (PY) in the first 7-12 months and 0.3-0.9 per 100 PY from 13 months to 5 years thereafter. For initially susceptible strains, the incidence of resistance to isoniazid was 0.11 per 100 PY and for and rifampin was 0.06 per 100 PY in the first year and negligible thereafter, with an overall risk of 0.14% for isoniazid and 0.10% for rifampin. Resistance of M. tuberculosis to antituberculous agents, and in particular to isoniazid, is a growing problem in Ontario and is higher than elsewhere in Canada.

Chlamydia trachomatis cervical infection: prevalence and determinants among women presenting for routine gynecologic examination.

OBJECTIVE: To determine the prevalence of and risk indicators for Chlamydia trachomatis cervical infection among women presenting for a periodic medical examination. DESIGN: Prevalence study. SETTING: Centre local de services communautaires (CLSC) Saint-Louis du Parc, Montreal. PATIENTS: All women presenting for a routine gynecologic examination from May 1985 to July 1986. Of the 773 (99%) who agreed to participate 56 were excluded because of inadequate diagnostic tests (34), antibiotic intake in the preceding 6 weeks (19) or loss to follow-up after the initial visit (3). OUTCOME MEASURES: Culture was the diagnostic standard, but rapid diagnostic tests were also used. From the identified cases logistic regression analysis was used to evaluate the following risk indicators: age, place of residence, use of oral contraceptives, sexual partners and frequency, history of sexually transmitted disease (STD) and abnormalities found on genital examination. MAIN RESULTS: Fifty-one of the women were found to have C. trachomatis infection, for a prevalence rate of 7.1%; 32 (63%) were completely asymptomatic. Three independent indicators were found: age of 25 years or less (odds ratio [OR] 3.2, 95% confidence limits [CL] 1.8 and 5.9), cervical erythema, contact bleeding or mucopurulent exudate (OR 2.5, 95% CL 1.4 and 4.5) and residency in the CLSC area (OR 2.3, 95% CL 1.1 and 5.1). A history of STD or vaginitis had a significant protective effect in women 30 years of age or more (OR 0.2). CONCLUSIONS: Case-finding for chlamydial infection could be an effective public health measure among women 25 years of age or less and among those with signs of cervicitis when they present for a Papanicolaou test.

HIV infection among women undergoing abortion in Montreal.

OBJECTIVE: To determine the seroprevalence and correlates of HIV infection in a subpopulation of women of childbearing age in Montreal. DESIGN: Anonymous unlinked seroprevalence study. SETTING: Pregnancy termination unit in a teaching hospital in Montreal. PARTICIPANTS: Women presenting for abortion from July 1989 to June 1993 who resided in Quebec and were not known to have HIV infection; 12,017 (99.6%) of 12,068 eligible women were included in the study. INTERVENTION: HIV antibody testing of serum left over from samples obtained for routine Rh typing; the same algorithm as for serodiagnostic testing, namely enzyme immunoassay (EIA) followed by confirmatory testing of repeatedly EIA-reactive samples, was used. OUTCOME MEASURES: HIV serostatus by age, marital status, region of residence (metropolitan Montreal versus other), country of birth and number of living children. RESULTS: Most (84.7%) of the subjects resided in metropolitan Montreal. The median age was 27.0 (range 13 to 50) years. The serum samples of 22 women were confirmed to be HIV positive, for an overall seroprevalence rate of 1.8 per 1000 (95% confidence interval 1.1 to 2.8). The seroprevalence rate did not vary significantly by age, marital status, region of residence or study year. However, it was strongly correlated with country of birth: Canada 0.16, Haiti 23.5, HIV-endemic countries other than Haiti 5.3 and non-HIV-endemic countries other than Canada 0.0 per 1000. The seroprevalence rate among women born in Haiti was 147 times higher than that among women born in Canada (p < 0.0001). Of the women born in Haiti the rate was 3.0 times greater among those who immigrated to Canada in 1985 or later than among those who immigrated earlier (p = 0.047). CONCLUSIONS: The results of this study indicate that the HIV seroprevalence rate among women in Montreal is strongly associated with country of birth, women born in HIV-endemic countries, especially Haiti, having the highest rate. These results will help in the development of policies regarding HIV antibody testing and prevention of HIV transmission in Quebec.