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PubMed1989

Sex worker, client sex behaviour and condom use in Harare, Zimbabwe.

One-hundred sex workers and 100 clients were interviewed at a bar/disco complex in Harare, Zimbabwe in 1989. Sociodemographic characteristics of sex workers and clients were examined. Almost a third of sex workers and nearly 90% of clients had engaged in commercial sex over 5 or more years. Sex workers reported that they worked an average of 4.6 nights a week, averaged 2.2 clients a night and charged a mean of Z$8.7 per session and Z$19.8 per night. Clients reported that they averaged 7.4 visits a month to a sex worker and paid a mean of Z$6.2 per session and Z$17.2 per night. Over half the sex workers said their last client was drunk and nearly two-thirds said he was a repeat client. Sex workers and clients were asked about the sex behaviours completed in their last paid sex act. Vaginal intercourse was reported by 98% of sex workers and clients alike. Manual stimulation of the sex worker's and client's genitalia was reported by roughly 80% of sex workers and clients. Oral and anal sex were rarely reported. Fifty-four percent of sex workers and 44% of clients reported using a condom in their last paid sex act. Client reports thus suggest that sex worker reports of sex acts and condom use with the last client possess considerable validity. Ethnographic approaches were used to study the social and work environment of sex workers. Ethnographic analysis demonstrated a lack of organisation among sex workers and a need to develop cohesive groups for successful health interventions. The study also highlighted the need to include clients in health interventions, the possible role of alcohol as an impediment to health interventions and the feasibility of using bar/disco security and the bar personnel as health educators.

Adolescent↗
PubMed1994

Discordant birthweight and late fetal death in like-sexed and unlike-sexed twin pairs: a population-based study.

OBJECTIVE: To study the relation between pregnancy loss (one or two fetal deaths in a pair) in twin pregnancy and gender (like-sexed and unlike-sexed pairs), discordant birthweight, and placentation. DESIGN: The type of placentation for gestations with pregnancy loss was studied, based on material retrieved from the original medical records, for a defined region comprising 20.0% of the total twin population. SUBJECTS AND SETTING: Four thousand one hundred and ninety-one unlike-sexed and 10,875 like-sexed twin pairs born in Sweden between 1973 and 1989, in most cases with a gestational duration 28 or more completed weeks. RESULTS: The relative risk (RR) for pregnancy loss in like-sexed pairs, compared with unlike-sexed ones, was 2.3 and the 95% confidence limits (CL) 1.7-3.1. Not until discordance exceeded 999 g did the pregnancy loss rate for unlike-sexed pairs increase significantly, compared with the (first) stratum with discordance less than 250 g (RR = 6.3; CL 3.5-11.3). For like-sexed twin pairs a higher pregnancy loss rate, compared with the first stratum, was seen already in the stratum with discordance 250-499 g (RR = 1.3; CL 1.0-1.8); a significant increase in pregnancy loss rate was found in all the three strata 500-749 g (RR = 2.1; CL 1.5-3.0), 750-999 g (RR = 3.5; CL 2.3-3.0), and 1000 g or more (RR = 10.9; CL 8.4-14.2), respectively. When calculating the discordance as a percentage of the weight of the larger twin, unlike-sexed pairs experienced a significant increase in pregnancy loss when discordance exceeded 40 to 50%. For like-sexed ones, the corresponding figures were 20 to 30%. In the 47 unlike-sexed pregnancies complicated by pregnancy loss, both twins died in two pregnancies (4.3%), whereas for like-sexed pairs the corresponding figures were 65/279 (23.3%). Of 47 gestations with pregnancy loss in a defined region, 32 were monochorionic (monozygous), nine were like-sexed dichorionic (monozygous or dizygous), and six were unlike-sexed (dizygous). CONCLUSIONS: Pregnancy loss was twice as high in like-sexed compared with unlike-sexed pairs, and only in like-sexed pairs was pregnancy loss strongly correlated to birthweight discordance. In twin pregnancies with one fetal death the risk for the surviving twin to succumb is five to six times higher in like-sexed compared with unlike-sexed pairs and is most probably related to monochorionicity.

Birth Weight↗
PubMed2006

Sex-specific sibling interactions and offspring fitness in vertebrates: patterns and implications for maternal sex ratios.

Vertebrate sex ratios are notorious for their lack of fit to theoretical models, both with respect to the direction and the magnitude of the sex ratio adjustment. The reasons for this are likely to be linked to simplifying assumptions regarding vertebrate life histories. More specifically, if the sex ratio adjustment itself influences offspring fitness, due to sex-specific interactions among offspring, this could affect optimal sex ratios. A review of the literature suggests that sex-specific sibling interactions in vertebrates result from three major causes: (i) sex asymmetries in competitive ability, for example due to sexual dimorphism, (ii) sex-specific cooperation or helping, and (iii) sex asymmetries in non-competitive interactions, for example steroid leakage between fetuses. Incorporating sex-specific sibling interactions into a sex ratio model shows that they will affect maternal sex ratio strategies and, under some conditions, can repress other selection pressures for sex ratio adjustment. Furthermore, sex-specific interactions could also explain patterns of within-brood sex ratio (e.g. in relation to laying order). Failure to take sex-specific sibling interactions into account could partly explain the lack of sex ratio adjustment in accordance with theoretical expectations in vertebrates, and differences among taxa in sex-specific sibling interactions generate predictions for comparative and experimental studies.

Adaptation, Biological↗
PubMed2003

Participatory mapping of sex trade and enumeration of sex workers using capture-recapture methodology in Diego-Suarez, Madagascar.

BACKGROUND: Capture-recapture methodology has been employed to estimate the size of hidden or difficult-to-reach human populations such as sex workers, homeless persons, and intravenous drug users. This study took place in the context of efforts to improve the quality of curative and preventive services for sexually transmitted infections offered to sex workers in Diego-Suarez, Madagascar in partnership with sex workers. GOAL: The goal of this study was to better understand sex-trading practices, map out sex work sites, and estimate the size of a mobile sex-worker population in Diego-Suarez, Madagascar using methods that can be reproduced in other resource-poor settings. STUDY DESIGN: Forty sex workers were trained to function as field researchers. Key informants in designated neighborhoods were identified and interviewed. Basic maps of sex-trade sites were designed by hand. The number of sex workers in Diego-Suarez was estimated using capture-recapture methodology. An educational brochure was used to "capture" sex workers during a first phase, and "recapture" 2 weeks later. RESULTS: Most sex trade was street based and mobile. Capture-recapture methods estimated a total of 2684 sex workers (95% CI: 2588-2780) in Diego-Suarez, or approximately 12% of the 15- to 49-year-old female population in the city. CONCLUSION: Geographic mapping and capture-recapture proved to be low-cost and relatively easy to use techniques for counting a hard-to-reach population, such as female street-based sex workers. Sex workers can be capable fieldworkers, and their active participation in research concerning sex work should be considered whenever possible. A high proportion of women of reproductive age were found to engage in sex work, indicating that there is an urgent need to scale up sexually transmitted infection and HIV prevention activities targeting sex workers, their sexual partners, and the general population.

Adolescent↗
PubMed2006

Vulnerability to HIV infection among sex worker and non-sex worker female injecting drug users in Dhaka, Bangladesh: evidence from the baseline survey of a cohort study.

BACKGROUND: Very little is known about female injecting drug users (IDU) in Bangladesh but anecdotal evidence suggests that they are hidden and very vulnerable to HIV through both their injection sharing and sexual risk behaviors. In order to better understand the risks and vulnerability to HIV of female IDU, a cohort study was initiated through which HIV prevalence and risk behaviors was determined. METHODS: All female IDU (those who had injected in the last six months and were 15 years or older) who could be identified from three cities in the Dhaka region were enrolled at the baseline of a cohort study. The study was designed to determine risk behaviors through interviews using a semi-structured questionnaire and measure prevalence of HIV, hepatitis C and syphilis semiannually. At the baseline of the cohort study 130 female IDU were recruited and female IDU selling sex in the last year (sex workers) versus those not selling sex (non-sex workers) were compared using descriptive statistics and logistic regression. RESULTS: Of the 130 female IDU enrolled 82 were sex workers and 48 were non-sex workers. None had HIV but more sex workers (60%) had lifetime syphilis than non-sex workers (37%). Fewer sex worker than non-sex worker IDU lived with families (54.9% and 81.3% respectively), but more reported lending needles/syringes (29.3% and 14.6% respectively) and sharing other injection paraphernalia (74.4% and 56.3% respectively) in the past six months. Although more sex workers used condoms during last sex than non-sex workers (74.4% and 43.3% respectively), more reported anal sex (15.9% and 2.1% respectively) and serial sex with multiple partners (70.7% and 0% respectively). Lifetime sexual violence and being jailed in the last year was more common in sex workers. CONCLUSION: Female IDU are vulnerable to HIV through their injection and sexual risk behaviors and sex worker IDU appear especially vulnerable. Services such as needle exchange programs should become more comprehensive to address the needs of female IDU.

Journal Article↗
PubMed2006

Sex ratio, life-history invariants, and patterns of sex change in a family of protandrous gastropods.

Application of optimality theory to the evolution of life histories has been broadly successful in predicting the conditions favoring sex change, the type of change, and the timing of such changes. The size advantage hypothesis predicts that the optimal size at which an individual should change sex is a function of its size and the size and sex of its potential mates. I collected data on the size, sex, and grouping of individuals of 27 populations of 19 species of the calyptraeids, a family of protandrous marine gastropods that includes Crepidula. These data are used to test the following predictions about variation in size at sex change: (1) sex ratio is biased toward the first sex; (2) the ratio of the size at sex change to the maximum size is a life-history invariant; and (3) species that form variable-sized groups or stacks have more variation in size at sex change than species that show less variation in stack formation. Across all 19 species, sex ratio was not significantly more often biased toward the first sex than it was toward the second sex, although sex ratios were significantly male biased more often than they were significantly female biased. Sex ratios ranged from 0.05 to 0.91, and this variation was related to mode of development, skew in size distribution, and frequency of stacking, but not with maximum body size. There was little evidence that the ratio of size at sex change and maximum size is invariant. There is evidence that one of the main underlying assumptions of this life-history invariant, that male fertility increases with the same function of size in all species, is invalid for calyptraeids and probably for other animals. Finally, species that form larger stacks or mating groups had more variation in size at sex change within a population than species that were generally solitary. These results suggest that information about individual groupings should be included in predictions of life-history theory and that more information about the relationship between male fitness and size is also needed.

Animals↗
PubMed2004

HIV, syphilis infection, and sexual practices among transgenders, male sex workers, and other men who have sex with men in Jakarta, Indonesia.

OBJECTIVES: To establish the prevalence of HIV, syphilis, and sexual risk behaviour among three groups of men who have sex with men in Jakarta, Indonesia, and to investigate sexual links between these men and broader heterosexual populations. METHODS: Anonymous, cross sectional surveys among community recruited transgender and male sex workers and self recognised men who have sex with men (MSM) were undertaken in mid-2002 in Jakarta, Indonesia. Places where transgender and male sex workers sell sex and where men go to meet non-commercial male sex partners were mapped. Probability samples were selected for the sex worker populations, while a mixed probability and convenience sample was drawn for self recognised MSM. Blood was drawn for HIV and syphilis serology and community interviewers administered a standardised questionnaire. RESULTS: HIV prevalence was 22% among transgender sex workers, 3.6% among male sex workers, and 2.5% among self recognised MSM, and syphilis prevalence was 19.3%, 2.0% and 1.1% respectively. 59.3% of transgender sex workers and 64.8% of male sex workers reported recent unprotected anal intercourse with clients, and 53.1% of other MSM reported unprotected anal sex with male partners. Some 54.4% of male sex workers and 18.3% of other MSM reported female partners in the preceding year. CONCLUSION: HIV has reached substantial levels among transgender sex workers, and is not negligible in other MSM groups. Risk behaviour is high in all subpopulations, and bisexual behaviour is common, meaning the threat of a wider epidemic is substantial. Prevention programmes targeting male-male sex are needed to reduce this threat.

Adult↗
PubMed2006

Sex in Geneva, sex in Lilongwe, and sex in Balaka.

This paper compares three interpretations of women and the transmission of HIV in rural Malawi. One is disseminated world-wide by institutions with a global reach such as the World Health Organization in Geneva and United States Agency for International Development (USAID); the second is provided by urban Malawians situated in the capital of Lilongwe, the seat of government and the site of the many international and national non-governmental agencies; the third is articulated by rural women and men in Balaka District, Malawi. We focus on women's motivations for extramarital sex, using qualitative interview data. We find that whereas in Geneva and Lilongwe women from rural Malawi are said to engage in sexual relationships outside of marriage because they need money for survival, in Balaka they are said to be motivated not only by money for survival but also for attractive consumer goods as well as by passion and by revenge for a husband's infidelity. We also find that data collection procedures influence explanations for women's affairs, as does the respondent's gender. An implication of this study is that AIDS-prevention policies based on the view from Geneva and Lilongwe need modification for Balaka, and by implication for rural Africa more generally.

Adolescent↗
PubMed2002

Risk of HIV infection attributable to oral sex among men who have sex with men and in the population of men who have sex with men.

We examined HIV infection and estimated the population-attributable risk percentage (PAR%) for HIV associated fellatio among men who have sex with other men (MSM). Among 239 MSM who practised exclusively fellatio in the past 6 months, 50% had three partners, 98% unprotected; and 28% had an HIV-positive partner; no HIV was detected. PAR%, based on the number of fellatio partners, ranges from 0.10% for one partner to 0.31% for three partners. The risk of HIV attributable to fellatio is extremely low.

Adult↗
PubMed2000

The influence of gender on sex: a study of men's and women's self-reported high-risk sex behavior.

An investigation is presented of the relationship between gender and five self-reported high-risk sex behaviors: ever having had casual sex, the lifetime number of vaginal sex partners, the lifetime number of anal sex partners, having had multiple vaginal sex partners over the short term, and having had multiple anal sex partners over the short term. The analysis was guided by a conceptual model that emphasized the constraints and opportunities for high-risk sex behavior that arise from an individual's structural position and cultural context. Gender differences in high-risk sex behaviors were predicted to be due to differences in men's and women's family roles, work roles, religious behaviors, and past sex experience. In addition, the effects of certain sociocultural factors on the high-risk sex behaviors were expected to be dependent on an individual's gender. The hypotheses were evaluated using national data from the United States on self-reported sex behaviors for men ages 20 to 39 years old and women ages 20 to 37 years old. Data analyses were conducted using ordinary least-squares regression and logistic regression. Findings provided mixed support for the predictions. Gender was not significantly related to short-term, self-reported high-risk sex behaviors once social and cultural factors were included in the statistical models. But it continued to predict lifetime behaviors. Several variables, including race, age, age at first sex, and marital status, had gender-specific effects on the self-reported high-risk sex behaviors. The study demonstrates how the effects of structural and cultural factors on sex behavior differ for men and women.

Adolescent↗
PubMed2001

Differences in sexual risk behaviors between college students with same-sex and opposite-sex experience: results from a national survey.

The goal of this study was to identify differences in the sexual health behaviors (condom use and number of sexual partners) between college students with same-sex sexual experiences and those with only opposite-sex partners. Data from a random sample of American university students were gathered as part of the 1997 College Alcohol Study. Odds ratios were estimated for consistent condom use and multiple sex partners for students with same-sex or both-sex sexual partners compared to those with exclusively heterosexual contacts. Five percent of respondents reported ever having a same-sex partner. Significant differences in safer-sex practices were found between groups. Females with both-sex experience and males with both-sex or only same-sex experiences were more likely to report multiple recent sexual partners than their peers with only opposite-sex partners. Odds ratios of consistent condom use were lower for men with only same-sex experience than among those with only opposite-sex partners. Findings have implications for sexual health education on the college campus. Consistent condom use remains low among college students. Education programs should emphasize the importance of limiting the number of lifetime sex partners, especially among students with same-sex experiences.

Adolescent↗
PubMed2003

Sex in Australia: experiences of commercial sex in a representative sample of adults.

OBJECTIVE: To describe the characteristics of Australian adults' experience of commercial sex. METHOD: Telephone interviews were completed by a representative sample of 10,173 men and 9,134 women aged 16-59 years (response rate 73.1%; 69.4% men, 77.6% women). Respondents were asked about their experiences both as clients and as sex workers. Socio-demographic and health factors associated with experience of commercial sex were explored for men. RESULTS: Almost one in six Australian men (15.6%) have ever paid for sex; 1.9% had done so in the past year. Of men who had ever paid for sex, 97% had paid for sex with a woman and 3% for sex with a man. Very few women (0.1%) had ever paid for sex. Twice as many men (0.9%) as women (0.5%) had ever been paid for sex; two-thirds of these men (0.6%) were paid by other men. Condom use during vaginal sex was highest in parlours and brothels and with escorts, and lowest for street sex work. Two-thirds of women who had ever been paid for sex had done so only overseas. One in 10 men who had paid for sex had only done so overseas. Men who had paid for sex were more likely than other men to smoke, to drink more alcohol, to have had a sexually transmitted infection or been tested for HIV, to have more sexual partners, to have first had vaginal intercourse before 16, and to have had heterosexual anal intercourse. CONCLUSION: Sex work overseas, where condom use may not be common, represents a potential source of HIV or sexually transmitted infection.

Adolescent↗
PubMed2003

Associations between internet sex seeking and STI associated risk behaviours among men who have sex with men.

OBJECTIVE: This exploratory study identified associations between internet sex seeking and HIV associated risk behaviours among a high risk sample of men who have sex with men (MSM). METHODS: A cross sectional survey of men attending a sex resort was conducted. Of 164 men asked to participate, 91% completed a self administered questionnaire. The questionnaire assessed demographic variables and (using a 3 month recall period) men's HIV associated sexual risk behaviours. Potential confounding variables were assessed and controlled, as needed, by multivariate analysis. RESULTS: Men currently resided in 14 states. One sixth reported being HIV positive. 57% of the men reported using the internet to seek sex. Differences in critical behaviours (unprotected anal sex and number of partners) were not found. However, compared to those not seeking sex by internet, men using the internet to meet sex partners were more likely to report fisting (adjusted odds ratio = 3.3, p = 0.04), having group sex (prevalence ratio (PR) = 1.2, p = 0.0001), using poppers during sex (PR = 1.94, p = 0.0001), and using ecstasy during sex (PR = 2.7, p = 0.04). Internet sex seeking men were also significantly more likely to report meeting sex partners in bathhouses (PR = 2.2, p = 0.0001), bars (PR = 1.5, p = 0.001), parks (PR = 3.2, p = 0.006), and circuit parties (PR = 8.9, p = 0.007). CONCLUSION: Among MSM attending a sex resort, those using the internet to seek sex partners may have modestly elevated risks for acquiring or transmitting sexually transmitted infections. Subsequent studies should investigate the utility of using the internet as forum for promoting safer sex behaviours among high risk MSM.

Adult↗