Sexual behaviour survey in a rural area of northwest Tanzania

The distribution of sex acts and condom use within partnerships in a rural sub-Saharan African population

INTRODUCTION

In an HIV/AIDS epidemic driven primarily by heterosexual transmission, it is important to have an understanding of the human sexual behaviour patterns that influence transmission. We analysed the distribution and predictors of within-partnership sexual behaviour and condom use in rural Zimbabwe and generated parameters for use in future modelling analyses.

METHODS

A population-based cohort was recruited from a household census in 12 communities. A baseline survey was carried out in 1998-2000 with follow-up surveys after 3 and 5 years. Statistical distributions were fitted to reported within-partnership numbers of total, unprotected and protected sex acts in the past two weeks. Multilevel linear and logistic regression models were constructed to assess predictors of the frequency of unprotected sex and consistent condom use.

RESULTS

A normal distribution of ln(sex acts+1) provided the best fit for total and unprotected sex acts for men and women. A negative binomial distribution applied to the untransformed data provided the best fit for protected sex acts. Condom use within partnerships was predominantly bimodal with at least 88% reporting zero or 100% use. Both men and women reported fewer unprotected sex acts with non-regular compared to regular partners (men: 0.26 fewer every two weeks (95% confidence interval 0.18-0.34); women: 0.16 (0.07-0.23)). Never and previously married individuals reported fewer unprotected sex acts than currently married individuals (never married men: 0.64 (0.60-0.67); previously married men: 0.59 (0.50-0.67); never married women: 0.51 (0.45-0.57); previously married women: 0.42 (0.37-0.47)). These variables were also associated with more consistent condom use.

DISCUSSION

We generated parameters that will be useful for defining transmission models of HIV and other STIs, which rely on a valid representation of the underlying sexual network that determines spread of an infection. This will enable a better understanding of the spread of HIV and other STDs in this rural sub-Saharan population.

Do men and women report their sexual partnerships differently? Evidence from Kisumu, Kenya

CONTEXT

It is generally believed that men and women misreport their sexual behaviors, which undermines the ability of researchers, program designers and health care providers to assess whether these behaviors compromise individuals' sexual and reproductive health.

METHODS

Data on 1,299 recent sexual partnerships were collected in a 2007 survey of 1,275 men and women aged 18-24 and living in Kisumu, Kenya. Chi-square and t tests were used to examine how sample selection bias and selective partnership reporting may result in gender differences in reported sexual behaviors. Correlation coefficients and kappa statistics were calculated in further analysis of a sample of 280 matched marital and nonmarital couples to assess agreement on reported behaviors.

RESULTS

Even after adjustment for sample selection bias, men reported twice as many partnerships as women (0.5 vs. 0.2), as well as more casual partnerships. However, when selective reporting was controlled for, aggregate gender differences in sexual behaviors almost entirely disappeared. In the matched-couples sample, men and women exhibited moderate to substantial levels of agreement for most relationship characteristics and behaviors, including type of relationship, frequency of sex and condom use. Finally, men and women tended to agree about whether men had other nonmarital partners, but disagreed about women's nonmarital partners.

CONCLUSIONS

Both sample selection bias and selective partnership reporting can influence the level of agreement between men's and women's reports of sexual behaviors. Although men report more casual partners than do women, accounts of sexual behavior within reported relationships are generally reliable.

Sexual practices among unmarried adolescents in Tanzania

BACKGROUND

Sexual activities are increasingly changing from the cultural point of view what they used to be. Knowledge of these practices among adolescents may be a basis to create awareness among adolescents on practices that involve risks. This study aims to assess sexual practices among unmarried adolescents in Tanzania.

METHODS

A cross-sectional survey was conducted among in-school and out-of-school but unmarried adolescents aged 10 to 19 in five locations in Tanzania. A questionnaire was used to collect information and to characterize sexual practices among these adolescents.

RESULTS

About 32% of adolescents reported being sexually active; a higher proportion being males than females. The only inquired and reported sexual practices include vaginal sex, masturbation, oral and anal sex. About 15% of sexually active adolescents reported having multiple sexual partners. Significantly more males reported having multiple partners than females. Nearly 42% of sexually active adolescents reported having used a condom during most recent sexual act. Females reported older partners at first sexual act.

CONCLUSION

Adolescents experience several sexual practices that include penetrative and non-penetrative. More males reported being sexually active than females. Despite adolescents reporting having multiple sexual partners, reported condom use during the most recent sexual act was low. We advocate for a more enhanced approach of reproductive health education that includes safer sex to adolescents without forgetting those in-schools.

Influence of timing of sexual debut and first marriage on sexual behaviour in later life: findings from four survey rounds in the Kisesa cohort in northern Tanzania

OBJECTIVES

To evaluate quality of sexual debut and first marriage data, measure trends and study the association of risky sexual behaviour in youth with adult risk behaviour.

METHODS

Reports on age at first sex (AFS) and age at first marriage (AFM) from the Kisesa cohort study, 1994-2004, were evaluated for consistency and used to describe trends in median age-at-event and time spent single but sexually active in different birth cohorts. The association of these variables with marital stability and numbers of partners at later ages was explored using statistical regression techniques.

RESULTS

AFS and AFM were inconsistently reported by 32% and 33% of respondents, respectively, but there was no general tendency to report lower or higher ages at a later report date. In 10-year birth cohorts born between 1950-9 and 1980-9, male median AFS declined from 18.1 to 17.0 years and female median AFM rose from 16.2 to 16.6 years. Young people of both sexes currently spend longer sexually active but unmarried than previously. Early marriage is statistically associated with remarriage and polygamy; longer time between sexual debut and marriage is associated with higher numbers of partners at later stages of life.

CONCLUSION

Inconsistent reporting of age-at-event introduces noise but does not bias estimates of population level indicators. Lengthening time spent single and sexually active suggests that men and women entering first marriage will have been exposed to increased numbers of non-marital partners. Successful youth interventions may also influence adult behaviour.

Predictors of risky sexual behavior among adolescents in Tanzania

Studies on sexual behavior among adolescents are fundamental in understanding and fighting against outcomes of unprotected sex that include unplanned/unwanted pregnancies and sexually transmitted diseases. This survey conducted among in- and out-of-schools adolescents measured prevalence of sexual behavior variables, including risky sexual behavior and associated factors. Risky sexual behavior was defined as having first sex before 16 years, inconsistent condom use and having multiple sexual partners. About 30% of adolescents reported being sexually active; a higher proportion being among males than females and 24.5% of sexually active adolescents reported having multiple sexual partners. More males (37%) reported having multiple sexual partners than females (26%). Nearly 48% of unmarried sexually active adolescents reported having used a condom during the most recent sexual intercourse. Predictors of risky sexual behavior were being male, young age (10-14 years) and being inschool. Preventive information and education should take into consideration these factors.

Behavioural data as an adjunct to HIV surveillance data

BACKGROUND

Second generation surveillance for HIV aims to improve the validity and utility of routine serial HIV prevalence data. It includes the collection of data on sexual behaviour and sexually transmitted disease prevalence.

METHODS

This paper reviews the function of sexual behaviour data in HIV surveillance and the methods used to determine which behaviours are monitored and how changes in behaviour can be assessed.

RESULTS

Sexual behaviour data provide a poor predictor of the future spread of HIV, but these data can provide corroboration of changes in HIV incidence and assist in attributing changes to particular aspects of risk. Significance tests should be used to assess changes in behaviour, but this requires transparent reporting of methods and sample sizes.

CONCLUSIONS

Collection of behavioural data will provide important retrospective information about the HIV epidemic progress and should not be neglected because of the focus on improving HIV sero-surveillance.

Potential Impact of Antiretroviral Therapy on HIV-1 Transmission and AIDS Mortality in Resource-Limited Settings

OBJECTIVE

To estimate the potential impact of antiretroviral therapy on the heterosexual spread of HIV-1 infection and AIDS mortality in resource-limited settings.

METHODS

A mathematic model of HIV-1 disease progression and transmission was used to assess epidemiologic outcomes under different scenarios of antiretroviral therapy, including implementation of World Health Organization guidelines.

RESULTS

Implementing antiretroviral therapy at 5% HIV-1 prevalence and administering it to 100% of AIDS cases are predicted to decrease new HIV-1 infections and cumulative deaths from AIDS after 10 years by 11.2% (inter-quartile range [IQR]: 1.8%-21.4%) and 33.4% (IQR: 26%-42.8%), respectively. Later implementation of therapy at endemic equilibrium (40% prevalence) is predicted to be less effective, decreasing new HIV-1 infections and cumulative deaths from AIDS by 10.5% (IQR: 2.6%-19.3%) and 27.6% (IQR: 20.8%-36.8%), respectively. Therapy is predicted to benefit the infected individual and the uninfected community by decreasing transmission and AIDS deaths. The community benefit is greater than the individual benefit after 25 years of treatment and increases with the proportion of AIDS cases treated.

CONCLUSIONS

Antiretroviral therapy is predicted to have individual and public health benefits that increase with time and the proportion of infected persons treated. The impact of therapy is greater when introduced earlier in an epidemic, but the benefit can be lost by residual infectivity or disease progression on treatment and by sexual disinhibition of the general population.

High-risk behaviour in young men attending sexually transmitted disease clinics in Pune, India

The present study reports sexual risk factors associated with HIV infection among men attending two sexually transmitted disease (STD) clinics in Pune, India and compares these behaviours between young and older men. Between April 1998 and May 2000, 1872 STD patients were screened for HIV infection. Data on demographics, medical history and sexual behaviour were collected at baseline. The overall HIV prevalence was 22.2%. HIV risk was associated with being divorced or widowed, less educated, living away from the family, having multiple sexual partners and initiation of sex at an early age. The risk behaviours in younger men were different to older men. Younger men were more likely to report early age of initiation of sex, having friends, acquaintances or commercial sex workers as their regular partners, having premarital sex and bisexual orientation. Young men were more educated and reported condom use more frequently compared with the older men. Similar high HIV prevalence among younger and older men highlights the need for focused targeted interventions aimed at adolescents and young men and also appropriate interventions for older men to reduce the risk of HIV and STD acquisition.

Asking semi-literate adolescents about sexual behaviour: the validity of assisted self-completion questionnaire (ASCQ) data in rural Tanzania

OBJECTIVES

To develop and test a sexual behaviour survey method for semi-literate populations, combining the privacy of a self-completion questionnaire (SCQ) with the clarity of a face-to-face questionnaire (FFQ).

METHODS

In 1998, 6079 Tanzanian primary school students (mean age 15.1 years) were surveyed using an innovative assisted self-completion questionnaire (ASCQ). The format of the questionnaire was simple, all responses were closed, and conceptually complex questions such as those involving ranking or multiple answers were avoided. The ASCQ was administered to groups of 20 by a research assistant who read questions and answers aloud in two languages so pupils could tick or write responses independently. A total of 4958 of respondents from the 1998 ASCQ Cohort also participated in a 1998 FFQ interview and, in 2000, 4424 again completed an ASCQ.

RESULTS

In the 1998 ASCQ survey, 55.0% of males and 21.1% of females reported they had had vaginal intercourse, of whom 71.5% and 66.0%, respectively reported their first sexual relationship lasted for a week or less, and 49.5% and 59.6%, respectively reported they had had sex in the last 4 weeks. After adjustment for age, reported sex was associated with alcohol use in both males (OR = 1.57) and females (OR = 1.69), earning money for males (OR = 1.32) and not living with a mother for females (OR = 0.77). The vast majority of respondents did not appear to have difficulty completing the ASCQ, but 7.4% of 1998 respondents and 2.9% of 2000 respondents selected all first or all last answers in a section for which this was inconsistent. This bias was associated with female, less educated and more geographically remote respondents. Of those respondents who reported sex in the 1998 ASCQ survey, 32.1% reported fewer total partners in the 2000 ASCQ survey, 25.2% reported having had sex fewer times than originally reported, and 61.9% of those who reported having used a condom in 1998 reported never having used one in 2000. While the proportions reporting sex were very similar in the 1998 ASCQ and FFQ surveys, 37.9% of males and 59.2% of females reporting sex only did so on one of the two questionnaires. Higher proportions of respondents reported sensitive information in the ASCQ than the FFQ, although in some cases this may have related to answer order bias.

CONCLUSION

The results suggest that an ASCQ may be useful in assessing sexual behaviour in African adolescents, particularly for older, male and/or educated respondents. However, triangulation with data from other surveys raises questions about the validity of self-reported sexual behaviour in general.

Kunyenga, "real sex," and survival: assessing the risk of HIV infection among urban street boys in Tanzania

This article examines possible avenues of HIV infection among urban street boys in Tanzania. In doing so, it questions the ways that AIDS researchers have defined and approached the phenomenon of "survival sex" in East and Central Africa. The article specifically examines the boys' sexual networks, sexual practices, and attitudes regarding their own sexual behavior, including their perceived risk of HIV/AIDS infection. Seventy-five street boys aged eight to 20 from the city of Mwanza were interviewed. Results suggest that almost all street boys are involved in a sexual network in which homosexual and heterosexual behavior occurs. Homosexual practices are rooted in a complex set of behaviors and ideologies known as kunyenga, which is a situated aspect of life on the streets and helps maintain the boys' strong dependence on one another. A key aspect of the boys' sexual careers involves a decrease in kunyenga activity as they approach the age of 18 and an increase in heterosexual encounters after the age of 11. There appears to be a critical period between these ages in which heterosexual and kunyenga activities overlap. It is suggested that boys between these ages represent a potential bridge for HIV/AIDS infection between the general population and the relatively enclosed sexual network of street boys.

Epidemiology and control and curable sexually transmitted diseases: opportunities and problems

BACKGROUND

Despite the availability of safe and effective treatment, infection with bacterial sexually transmitted diseases persists at a high prevalence in many populations.

GOAL

To review the difficulties of parameter estimation when a cure is readily available and to explore the impact of different treatment and screening strategies that might maximize the benefits of using available treatments.

STUDY DESIGN

A standard deterministic model for the spread of a bacterial sexually transmitted disease that causes symptomatic and asymptomatic infections, in which the population is stratified according to sex and sexual activity, is further stratified into two host groups to enable the modeling of different treatment and screening strategies.

RESULTS

In the presence of a core group, if an infection has a high transmission probability, then screening for asymptomatic infections has a short-lived benefit. Repeated screening is slightly better if it is not restricted to a fraction of the at-risk population, but targeting of high-risk groups should be effective. Screening to treat asymptomatic infections in men could be beneficial if a substantial fraction of cases remain asymptomatic.

CONCLUSIONS

After the initial gains achieved through treating symptomatic infections, further reductions in the prevalence of infections can be achieved by finding asymptomatic infections. However, these gains are difficult to achieve, especially in the case of gonorrhea. Because men are likely to have an asymptomatic chlamydial infection, screening of men for chlamydia should be worthwhile.

Links between premarital sexual behaviour and extramarital intercourse: a multi-site analysis

OBJECTIVES

Data from Côte d'Ivoire, Tanzania, Lusaka and Thailand were used to explore the relationship between premarital and extramarital sexual activity in men.

DESIGN

Analysis was performed on data collected in the Global Programme on AIDS/WHO programme of stratified probability sample surveys of sexual behaviour of men and women aged 15 to at least 49 years interviewed face to face in 1989/1990. This analysis was restricted to male respondents currently married or in a regular partnership for at least a year.

METHODS

Predictors of extramarital intercourse (EMI) in the preceding year were assessed using crude and adjusted odds ratios (OR), and 95% confidence intervals were calculated for a set of behavioural and sociodemographic variables that were believed a priori to be associated with EMI.

RESULTS

Bivariate analysis showed that younger age at sexual debut, marriage to someone other than the debut partner and a higher number of sex partners before first marriage were significantly associated with enhanced probability of EMI in the past year in all sites. The adjusted OR indicated that in Côte d'lvoire and Tanzania the age at debut and in Tanzania and Thailand the number of sex partners before marriage were significantly associated with EMI in the past year.

CONCLUSION

Characteristics of premarital conduct such as age at sexual debut, length of acquaintance with debut partner and number of premarital partners were significantly associated with EMI in men later in life. This continuity in sexual conduct over the life course was open to several competing interpretations, but sexual socialization in adolescence was likely to be at least a contributory factor.

Uncertainties in predicting the demographic impact of AIDS

A model giving the demographic impact of AIDS is analysed to examine the sensitivity of the projections when various complicating features are included. The model deals with age and sexual partner change rate as continuous variables and uses a device to specify arbitrary correlations between the ages of the people who form sexual partnerships. The device ensures consistency, in that the amount of partner formation is the same regardless of whether the partnerships are counted from the point of view of males or females. Arbitrary correlation between partner change rate and fertility is also permitted. The results show the uncertainty in model predictions that population growth will reduce over the next 20 years to approximately zero in parts of East Africa severely affected by the AIDS epidemic. The main sources of uncertainty in the model predictions are assumptions concerning the correlation between ages in a partnership, the correlation between partner change rate and fertility, the incubation period of AIDS, and the variability of the female partner change rate.

The effect of follow-up on limiting non-participation bias in genetic epidemiologic investigations

The use of a comprehensive follow-up strategy to limit non-participation bias was evaluated in a population-based case-control study of orofacial clefts. Birth parents were requested to provide exposure data, and index children and parents were asked to provide blood specimens. Follow-up included telephone or postal reminders every two weeks for up to three months. Consent to participate was received from 281 (76.6%) case mothers and 246 (72.4%) case fathers. The corresponding totals for controls were 279 (54.7%) and 245 (49.8%). Evaluation of participation rates by intensity of follow-up showed that 23% of case and 18% of control families consented without reminders (first stage); 81% of cases and 83% of controls agreed following one or two reminders (second stage); and the remainder of participants consented following three or more reminders (final stage). Cumulative distributions of sociodemographic characteristics differed little between second and final stage participants. Odds ratios for maternal multivitamin use were similar between second and final stage participants, whereas those for maternal and paternal smoking tended to decline. Although follow-up measures were necessary to enroll most families, use of more than two reminders did not appear to increase the representativeness of the sample; however, termination of recruitment after only two reminders would have led to different conclusions. Future studies require data collection protocols that encourage participation from all population subgroups, and one alternative is presented.

Validity and reliability in reporting sexual partners and condom use in a Swiss population survey

OBJECTIVES

To examine the validity and reliability of indicators of sexual behaviour and condom use in annual telephone surveys (n=2800) of the general population aged 17 to 45 for the evaluation of AIDS prevention in Switzerland.

METHODS

A test-retest study with additional focused interviews was conducted on a subsample (n=138) of the respondents aged 17 to 22 years.

RESULTS

The subsample included more French speaking respondents (OR: 1.7, CI: 1.1-2.5) and more people in a stable relationship (OR: 2.2, CI: 1.5-3-3) than the initial sample but did not differ in any other way, although no data is available on their attitudes towards sex. The reliability of the indicators considered was high: number of lifetime, casual sex partners in the last 6 months and condom use with them, acquisition of a new steady partner during the year and condom use with this partner, condom use at last intercourse. However, the focused interviews raised questions about the validity of some of these indicators, presumably due to imprecise wording of the questionnaire items. Among sexually active respondents, 12.5% (95% CI: 4.7-25.5) of the men included non-penetrative sex in the definition of 'sexual intercourse', but only 1.9% (95% CI: 0.1-10.3) of the women. The propensity for men of counting acts or partners with whom no penetration had taken place in the total reported sex acts or partners was not significantly associated with any socio-demographic variables. In addition, among the 15 respondents who had reported consistent condom use with casual sex partners at interview, 40% (95% CI: 16.3-67.7) admitted at reinterview that sometimes they also had unprotected sex.

CONCLUSIONS

The reliability of reports on sexual behaviour and condom use in this Swiss evaluation survey is good. The indicators derived from the annual surveys are robust measures and the monitoring of trends seems to be based on reliable measurement. However, more research is required on the validity of the data.

Sexual and AIDS-Related Knowledge, Attitudes and Behaviors of Adolescents in Sierra Leone, West Africa

A survey of 307 Sierra Leonean adolescents between the ages of thirteen and nineteen was assessed to determine their sexual and AIDS-related knowledge, attitudes, and behaviors. Results indicate high sexual activity rates among the sampled group; 89 percent of the males and 68 percent of the females had engaged in sexual intercourse. The mean age at first sexual intercourse was found to be 14.4 years for males and 15.1 years for females. Sixty-five percent of the males and 35 percent of the females reported having three or more sexual partners over their lifetime. Other findings included high rates of STDs and HIV/AIDS, low reported condom use, low reported use of other birth control methods, and low knowledge scores concerning pregnancy prevention, HIV/AIDS and STDs. Implications of these findings are discussed.

A case-control analysis of risk factors in HIV transmission in South India

A case-control study was done among patients attending our clinic for sexually transmitted diseases in South India to assess risk factors for human immunodeficiency virus (HIV) infection. Of 5,876 patients tested, 105 (1.79%) were HIV antibody positive (87 men, 18 women) by enzyme-linked immunosorbent assay and Western blot. They were compared with an equal number of age- and sex-matched patients without HIV antibody. Risk factors significant in the crude odds ratio analysis were occupation (truck drivers and truck cleaners), age at first exposure, and sexual contact with commercial sex workers. In the logistic regression analysis, only a history of past genital ulcer was a significant risk factor. Other important findings of this study were that (a) the spread of HIV to women is mostly from their infected husbands and (b) regular condom use was reported by less than 8% of patients and controls. Obviously, the current methods of education of the population are far from adequate.

A study of sexual behavior change in rural Senegal

This study describes recent sociodemographic and behavioral changes in a rural community in Senegal and investigates how these changes may have modified the risk of HIV/STD transmission. The authors combine findings from two surveys: (a) a marriage survey among all adults of a rural community of approximately 7,000 inhabitants; and (b) a sexual practices survey conducted among a sample of the same population (165 men and 165 women) between 1989 and 1994. During the last 30 years--between 1955-64 and 1985-92--age at first marriage increased in the study area from 25 to 32 years for men and from 21 to 24 years for women. At the same time, age at first sexual intercourse decreased by approximately 10 years on average for men. As expected, this has led to an increase in premarital sexual activity, and we have documented both an increase in the percentage of individuals declaring sexual relations before marriage and, for men, an increase in the number of sexual partners before marriage. Multipartnership is more frequent among men than women (OR=4.4), among those who had their first intercourse at an early age (OR=3.3), among rural migrants (OR=2.7), and among those who had a good knowledge of AIDS. These findings show how recent changes in marriage, sexual behaviors, and seasonal migration have combined to increase the risk of HIV/STD infection within the community. Male rural migrants and their partners are particularly exposed.