The relationship between HIV and fertility in the era of antiretroviral therapy in sub-Saharan Africa: evidence from 49 Demographic and Health Surveys.

OBJECTIVES: To describe regional differences in the relative fertility of HIV-positive vs. HIV-negative women and changes as antiretroviral treatment (ART) is scaled up, to improve estimates of predicted need for and coverage of prevention of mother-to-child transmission services at national and subnational levels. METHODS: We analysed 49 nationally representative household surveys in sub-Saharan Africa between 2003 and 2016 to estimate fertility rate ratios of HIV-positive and HIV-negative women by age using exponential regression and test for regional and urban/rural differences. We estimated the association between national ART coverage and the relationship between HIV and fertility. RESULTS: Significant regional differences exist in HIV and fertility relationships, with less HIV-associated subfertility in Southern Africa. Age patterns of relative fertility are similar. HIV impact on fertility is weaker in urban than rural areas. For women below age 30, regional and urban/rural differences are largely explained by differences in age at sexual debut. Higher levels of national ART coverage were associated with slight attenuation of the relationship between HIV and fertility. CONCLUSIONS: Regional differences in HIV-associated subfertility and urban-rural differences in age patterns of relative fertility should be accounted for when predicting need for and coverage of PMTCT services at national and subnational level. Although HIV impacts on fertility are somewhat reduced at higher levels of national ART coverage, differences in fertility between HIV positive and negative remain, and fertility of women on ART should not be assumed to be the same as HIV-negative women. There were few data in recent years, when ART has reached high levels, and this relationship should continue to be assessed as further evidence becomes available.

Low mortality risk but high loss to follow-up among patients in the Tanzanian national HIV care and treatment programme.

UNLABELLED: OBJECTIVE To analyse survival and retention rates of the Tanzanian care and treatment programme. METHODS: Routine patient-level data were available from 101 of 909 clinics. Kaplan-Meier probabilities of mortality and attrition after ART initiation were calculated. Mortality risks were corrected for biases from loss to follow-up using Egger's nomogram. Smoothed hazard rates showed mortality and attrition peaks. Cox regression identified factors associated with death and attrition. Median CD4 counts were calculated at 6 month intervals. RESULTS: In 88,875 adults, 18% were lost to follow up 12 months after treatment initiation, and 36% after 36 months. Cumulative mortality reached 10% by 12 months (15% after correcting for loss to follow-up) and 14% by 36 months. Mortality and attrition rates both peaked within the first six months, and were higher among males, those under 45 kg and those with CD4 counts below 50 cells/µl at ART initiation. In the first year on ART, median CD4 count increased by 126 cells/µl, with similar changes in both sexes. CONCLUSION: Earlier diagnoses through expanded HIV testing may reduce high mortality and attrition rates if combined with better patient tracing systems. Further research is needed to explore reasons for attrition.

Declining child mortality in northern Malawi despite high rates of infection with HIV.

OBJECTIVE: To determine whether routine surveys, such as the Demographic and Health Surveys (DHS), have underestimated child mortality in Malawi. METHODS: Rates and causes of child mortality were obtained from a continuous-registration demographic surveillance system (DSS) in Malawi for a population of 32 000. After initial census, births and deaths were reported by village informants and updated monthly by project enumerators. Cause of death was established by verbal autopsy whenever possible. The likely impact of human immunodeficiency virus (HIV) infection on child mortality was also estimated from antenatal clinic surveillance data. Overall and age-specific mortality rates were compared with those from the 2004 Malawi DHS. FINDINGS: Between August 2002 and February 2006, 38 617 person-years of observation were recorded for 20 388 children aged < 15 years. There were 342 deaths. Re-census data, follow-up visits at 12 months of age and the ratio of stillbirths to neonatal deaths suggested that death registration by the DSS was nearly complete. Infant mortality was 52.7 per 1000 live births, under-5 mortality was 84.8 per 1000 and under-15 mortality was 99.1 per 1000. One-fifth of deaths by age 15 were attributable to HIV infection. Child mortality rates estimated with the DSS were approximately 30% lower than those from national estimates as determined by routine surveys. CONCLUSION: The fact that child mortality rates based on the DSS were relatively low in the study population is encouraging and suggests that the low mortality rates estimated nationally are an accurate reflection of decreasing rates.

Translating global health research aims into action: the example of the ALPHA network.

There is increasing consensus on the importance of strengthening global health research to meet health and development goals. Three key global health research aims are to ensure that research (i) addresses priority health needs, (ii) contributes to policy development, and (iii) adds value to investments in developing countries through South-South collaboration and capacity-strengthening in the South. The ALPHA network (Analysing Longitudinal Population-based HIV/AIDS data on Africa) is an illustrative example of how these global health research aims can be translated into action. The network facilitates additional collaborative HIV epidemiological research among six independent research projects in Africa studying population-based cohorts. Under the first of the earlier mentioned aims, the network addresses key epidemiology research issues in HIV/AIDS which are crucial to making progress and monitoring progress in the response against HIV/AIDS. Under the second aim, the network's scientific programme of research has contributed to strengthening the evidence base on HIV epidemiology in Africa and has informed policy development in areas such as targeted HIV prevention, social support, monitoring epidemic response and epidemic forecasting. Under the third aim, investment in the network has added value to the research investment in the individual projects through capacity development among African researchers as well as through the collaborative research outputs of the individual projects. Lessons from the network are relevant to collaborations facing similar challenges in other areas of global health research. These include the importance of establishing transparent and efficient governance for research collaborations, developing advance consensus on data sharing, ensuring effective communication for networking and demonstrating the added value of research investment in South-South collaborations.

Verbal autopsy can consistently measure AIDS mortality: a validation study in Tanzania and Zimbabwe.

BACKGROUND: Verbal autopsy is currently the only option for obtaining cause of death information in most populations with a widespread HIV/AIDS epidemic. METHODS: With the use of a data-driven algorithm, a set of criteria for classifying AIDS mortality was trained. Data from two longitudinal community studies in Tanzania and Zimbabwe were used, both of which have collected information on the HIV status of the population over a prolonged period and maintained a demographic surveillance system that collects information on cause of death through verbal autopsy. The algorithm was then tested in different times (two phases of the Zimbabwe study) and different places (Tanzania and Zimbabwe). RESULTS: The trained algorithm, including nine signs and symptoms, performed consistently based on sensitivity and specificity on verbal autopsy data for deaths in 15-44-year-olds from Zimbabwe phase I (sensitivity 79%; specificity 79%), phase II (sensitivity 83%; specificity 75%) and Tanzania (sensitivity 75%; specificity 74%) studies. The sensitivity dropped markedly for classifying deaths in 45-59-year-olds. CONCLUSIONS: Verbal autopsy can consistently measure AIDS mortality with a set of nine criteria. Surveillance should focus on deaths that occur in the 15-44-year age group for which the method performs reliably. Addition of a handful of questions related to opportunistic infections would enable other widely used verbal autopsy tools to apply this validated method in areas for which HIV testing and hospital records are unavailable or incomplete.

Mortality and health among internally displaced persons in western Kenya following post-election Violence; 2008: novel use of demographic surveillance

Objective To evaluate mortality and morbidity among internally displaced persons (IDPs) who relocated in a demographic surveillance system (DSS) area in western Kenya following post-election violence. Methods In 2007; 204 000 individuals lived in the DSS area; where field workers visit households every 4 months to record migrations; births and deaths. We collected data on admissions among children 5 years of age in the district hospital and developed special questionnaires to record information on IDPs. Mortality; migration and hospitalization rates among IDPs and regular DSS residents were compared; and verbal autopsies were performed for deaths. Findings Between December 2007 and May 2008; 16 428 IDPs migrated into the DSS; and over half of them stayed 6 months or longer. In 2008; IDPs aged 15.49 years died at higher rates than regular residents of the DSS (relative risk; RR: 1.34; 95confidence interval; CI: 1.004.1.80). A greater percentage of deaths from human immunodeficiency virus (HIV) infection occurred among IDPs aged . 5 years (53) than among regular DSS residents (25.29) (P 0.001). Internally displaced children 5 years of age did not die at higher rates than resident children but were hospitalized at higher rates (RR: 2.95; 95CI: 2.44.3.58). Conclusion HIV-infected internally displaced adults in conflict-ridden parts of Africa are at increased risk of HIV-related death. Relief efforts should extend to IDPs who have relocated outside IDP camps; particularly if afflicted with HIV infection or other chronic conditions

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.

Comparative assessment of the quality of age-at-event reporting in three HIV cohort studies in sub-Saharan Africa.

OBJECTIVES: To assess inconsistencies in reported age at first sex (AFS) and age at first marriage (AFM) in three African cohorts, and consider their implications for interpreting trends in sexual and marital debut. METHODS: Data were analysed from population-based cohort studies in Zimbabwe, Uganda and South Africa with 3, 10 and 4 behavioural survey rounds, respectively. Three rounds over a similar time frame were selected from each site for comparative purposes. The consistency of AFS and AFM reports was assessed for each site by comparing responses made by participants in multiple surveys. Respondents were defined as unreliable if less than half of all their age-at-event reports were the same. Kaplan-Meier functions were used to describe the cumulative proportion (1) having had sex and (2) married by age, stratified by sex, birth cohort and site, to compare the influence of reporting inconsistencies on these estimates. RESULTS: Among participants attending all three comparable rounds, the percentage with unreliable AFS reports ranged from 30% among South African women to 56% among Zimbabwean men, with similar patterns observed for AFM. Inclusion of unreliable reports had little effect on estimates of median age-at-event in all sites. There was some evidence from the 1960-9 birth cohort that women in Uganda and both sexes in South Africa reported later AFS as they aged. CONCLUSION: Although reporting quality is unlikely to affect comparisons of AFS and AFM between settings, care should be taken not to overinterpret small changes in reported age-at-event over time within each site.

Trends in marriage and time spent single in sub-Saharan Africa: a comparative analysis of six population-based cohort studies and nine Demographic and Health Surveys.

OBJECTIVES: To describe trends in age at first sex (AFS), age at first marriage (AFM) and time spent single between events and to compare age-specific trends in marital status in six cohort studies. METHODS: Cohort data from Uganda, Tanzania, South Africa, Zimbabwe and Malawi and Demographic and Health Survey (DHS) data from Uganda, Tanzania and Zimbabwe were analysed. Life table methods were used to calculate median AFS, AFM and time spent single. In each study, two surveys were chosen to compare marital status by age and identify changes over time. RESULTS: Median AFM was much higher in South Africa than in the other sites. Between the other populations there were considerable differences in median AFS and AFM (AFS 17-19 years for men and 16-19 years for women, AFM 21-24 years and 18-19 years, respectively, for the 1970-9 birth cohort). In all surveys, men reported a longer time spent single than women (median 4-7 years for men and 0-2 years for women). Median years spent single for women has increased, apart from in Manicaland. For men in Rakai it has decreased slightly over time but increased in Kisesa and Masaka. The DHS data showed similar trends to those in the cohort data. The age-specific proportion of married individuals has changed little over time. CONCLUSIONS: Median AFS, AFM and time spent single vary considerably among these populations. These three measures are underlying determinants of sexual risk and HIV infection, and they may partially explain the variation in HIV prevalence levels between these populations.

Reported number of sexual partners: comparison of data from four African longitudinal studies.

OBJECTIVE: To compare reported numbers of sexual partners in Eastern and Southern Africa. METHODS: Sexual partnership data from four longitudinal population-based surveys (1998-2007) in Zimbabwe, Uganda and South Africa were aggregated and overall proportions reporting more than one lifetime sexual partner calculated. A lexis-style table was used to illustrate the average lifetime sexual partners by site, sex, age group and birth cohort. The male-to-female ratio of mean number of partnerships in the last 12 months was calculated by site and survey. For each single year of age, the proportion sexually active in the past year, the mean number of partners in the past year and the proportion with more than one partner in the past year were calculated. RESULTS: Over 90% of men and women between 25 and 45 years of age reported being sexually active during the past 12 months, with most reporting at least one sexual partner. Overall, men reported higher numbers of lifetime sexual partners and partners in the last year than women. The male-to-female ratio of mean partnerships in the last year ranged from 1.41 to 1.86. In southern African cohorts, individuals in later birth cohorts reported fewer sexual partners and a lower proportion reported multiple partnerships compared with earlier birth cohorts, whereas these behavioural changes were not observed in the Ugandan cohorts. Across the four sites, reports of sexual partnerships followed a similar pattern for each sex. CONCLUSIONS: The longitudinal results show that reductions in the number of partnerships were more evident in southern Africa than in Uganda.

The "seeded" focus group: a strategy to recruit HIV+ community members into treatment research.

OBJECTIVE(S): We piloted an innovative community-based recruitment approach to contact known HIV+ individuals for referral to treatment without endangering their confidentiality. METHODS: Nested within an HIV cohort study, operations research to monitor and improve rural uptake of antiretroviral therapy (ART) was conducted alongside the introduction of Tanzania's national treatment programme. We confronted the challenge of recruiting participants without inadvertently disclosing their HIV status to family or other community members. During post-test counselling, nurses compiled a list of HIV+ persons who expressed interest in being contacted when ART became available. Study numbers, but not names, of 12 "seeds" were added to a randomly generated list of residents, matched by age group and sex, and all were invited to participate in focus-group discussions on community perceptions of treatment. After the discussion, the original counsellors met each participant in private, inviting the "seed" for ART referral and offering VCT to others. RESULTS: Ten "seeds" were successfully located and attended the local focus-group discussion; all subsequently volunteered to undergo clinical tests in advance of receiving antiretroviral therapy. They also agreed to participate in a study of barriers to ART access. The other focus-group members contributed useful information on levels of understanding and support for treatment, and several came forward for HIV testing. CONCLUSIONS: The "seeded" focus group is a very straightforward and easily arranged method of recruiting HIV+ people for research or service delivery within a wider context of engaging with local community perceptions.

Scaling up stigma? The effects of antiretroviral roll-out on stigma and HIV testing. Early evidence from rural Tanzania.

OBJECTIVE: To investigate the interplay between antiretroviral therapy (ART) scale-up, different types of stigma and Voluntary Counselling and Testing (VCT) uptake 2 years after the introduction of free ART in a rural ward of Tanzania. METHODS: Qualitative study using in-depth interviews and group activities with a purposive sample of 91 community leaders, 77 ART clients and 16 health providers. Data were analysed for recurrent themes using NVIVO-7 software. RESULTS: The complex interplay between ART, stigma and VCT in this setting is characterised by two powerful but opposing dynamics. The availability of effective treatment has transformed HIV into a manageable condition which is contributing to a reduction in self-stigma and is stimulating VCT uptake. However, this is counterbalanced by the persistence of blaming attitudes and emergence of new sources of stigma associated with ART provision. The general perception among community leaders was that as ART users regained health, they increasingly engaged in sexual relations and "spread the disease." Fears were exacerbated because they were perceived to be very mobile and difficult to identify physically. Some leaders suggested giving ART recipients drugs "for impotence," marking them "with a sign" and putting them "in isolation camps." In this context, traditional beliefs about disease aetiology provided a less stigmatised explanation for HIV symptoms contributing to a situation of collective denial. CONCLUSION: Where anticipated stigma prevails, provision of antiretroviral drugs alone is unlikely to have sufficient impact on VCT uptake. Achieving widespread public health benefits of ART roll-out requires community-level interventions to ensure local acceptability of antiretroviral drugs.

Has the HIV epidemic in rural Mwanza, Tanzania reached a plateau?

Data from studies in Mwanza Region in Tanzania suggest stabilising HIV prevalence. The objective was to determine the factors that may have contributed to the relatively stable pattern of the HIV prevalence observed in the comparison communities of the Mwanza STD treatment trial in rural Mwanza Region, Tanzania between 1991 and 2001. Socio-demographic, sexual behaviour and HIV prevalence data in two surveys conducted 10 years apart in the same communities using similar sampling schemes were compared. The age standardised HIV prevalence was 3.8% (95% CI: 3.2-4.6) in 1991 and 4.3% (95% CI: 2.8-6.4) in 2001 for males (Z= - 0.56, P= 0.58); and 4.5% (95% CI: 3.8-5.3) in 1991 and 3.9% (95% CI: 2.6-5.6) in 2001 for females (Z= 0.64, P = 0.52). Participants in the 2001 survey reported significantly fewer lifetime and recent sexual partners (12 months), Sexually Transmitted disease syndromes (12 months) and significantly more condom use at last sex with casual partners than those in the 1991 behaviour survey. We conclude that STD/HIV infection prevention activities in rural Mwanza may be responsible for changes in risky sexual behaviour and have successfully impeded the spread of HIV infection. These activities should therefore be enhanced to reduce HIV incidence even further. In addition, modelling studies are needed to assess whether mobility of HIV infected people out of rural communities may stabilise the prevalence of the HIV infection in the general populations.

Low effectiveness of syndromic treatment services for curable sexually transmitted infections in rural South Africa.

OBJECTIVES: Syndromic sexually transmitted infection (STI) treatment remains a cost-saving HIV prevention intervention in many countries in Africa. We estimate the effectiveness of syndromic treatment for curable STIs in rural KwaZulu-Natal, South Africa, and the trend in STI prevalences before and after the introduction of syndromic treatment in 1995. METHODS: Data were available from various clinical studies, surveys of public and private health providers, the general population and women attending antenatal, family planning and child immunisation clinics in rural northern KwaZulu-Natal between 1987 and 2004. Overall effectiveness was defined as the estimated proportion of the annual number of symptomatic curable STI episodes cured by syndromic treatment based on separate estimates for six curable STI aetiologies by gender. RESULTS: Median overall effectiveness was 13.1% (95% CI 8.9 to 17.8%) of symptomatic curable STI episodes cured. Effectiveness increased to 25.0% (95% CI 17.3 to 33.8%), 47.6% (95% CI 44.5 to 50.8%) or 14.3% (95% CI 9.9 to 19.4%) if 100% treatment seeking, 100% correct treatment provision or 100% cure were assumed, respectively. Time-trends were difficult to assess formally but there was little evidence of decreasing STI prevalences. Including incurable but treatable herpes simplex virus (HSV)-2 ulcers in the effectiveness calculation would halve the proportion of ulcers cured or correctly treated, but this reduction could be entirely countered by including episodic antiviral treatment in the national guidelines. CONCLUSION: Overall effectiveness of syndromic treatment for curable STIs in rural KwaZulu-Natal remains low and there is little evidence of reduced curable STI prevalences. As syndromic treatment is likely to be a cost-saving HIV prevention intervention in South Africa, innovative strategies are urgently needed to increase rates of treatment seeking and correct treatment provision.

The Spectrum projection package: improvements in estimating mortality, ART needs, PMTCT impact and uncertainty bounds.

BACKGROUND: The approach to national and global estimates of HIV/AIDS used by UNAIDS starts with estimates of adult HIV prevalence prepared from surveillance data using either the Estimation and Projection Package (EPP) or the Workbook. Time trends of prevalence are transferred to Spectrum to estimate the consequences of the HIV/AIDS epidemic, including the number of people living with HIV, new infections, AIDS deaths, AIDS orphans, treatment needs and the impact of treatment on survival. METHODS: The UNAIDS Reference Group on Estimates, Modelling and Projections regularly reviews new data and information needs and recommends updates to the methodology and assumptions used in Spectrum. The latest update to Spectrum was used in the 2007 round of global estimates. RESULTS: Several new features have been added to Spectrum in the past two years. The structure of the population was reorganised to track populations by HIV status and treatment status. Mortality estimates were improved by the adoption of new approaches to estimating non-AIDS mortality by single age, and the use of new information on survival with HIV in non-treated cohorts and on the survival of patients on antiretroviral treatment (ART). A more detailed treatment of mother-to-child transmission of HIV now provides more prophylaxis and infant feeding options. New procedures were implemented to estimate the uncertainty around each of the key outputs. CONCLUSIONS: The latest update to the Spectrum program is intended to incorporate the latest research findings and provide new outputs needed by national and international planners.

Has the HIV Epidemic in Rural Mwanza; Tanzania Reached a Plateau?

Data from studies in Mwanza Region in Tanzania suggest stabilising HIV prevalence. The objective was to determine the factors that may have contributed to the relatively stable pattern of the HIV prevalence observed in the comparison communities of the Mwanza STD treatment trial in rural Mwanza Region; Tanzania between 1991 and 2001. Socio-demographic; sexual behaviour and HIV prevalence data in two surveys conducted 10 years apart in the same communities using similar sampling schemes were compared. The age standardised HIV prevalence was 3.8(95CI: 3.2-4.6) in 1991 and 4.3(95CI: 2.8-6.4) in 2001 for males (Z= - 0.56; P= 0.58); and 4.5(95CI: 3.8-5.3) in 1991 and 3.9(95CI: 2.6-5.6) in 2001 for females (Z= 0.64; P= 0.52). Participants in the 2001 survey reported significantly fewer lifetime and recent sexual partners (12 months); Sexually Transmitted disease syndromes (12 months) and significantly more condom use at last sex with casual partners than those in the 1991 behaviour survey. We conclude that STD/ HIV infection prevention activities in rural Mwanza may be responsible for changes in risky sexual behaviour and have successfully impeded the spread of HIV infection. These activities should therefore be enhanced to reduce HIV incidence even further. In addition; modelling studies are needed to assess whether mobility of HIV infected people out of rural communities may stabilise the prevalence of the HIV infection in the general populations

The social and economic impact of parental HIV on children in northern Malawi: retrospective population-based cohort study.

From population-based surveys in the 1980s in Karonga district, northern Malawi, 197 'index individuals' were identified as HIV-positive. 396 HIV-negative 'index individuals' were selected as a comparison group. These individuals, and their spouses and children, were followed up in 1998-2000. 582 of 593 index individuals were traced. 487 children of HIV-positive, and 1493 children of HIV-negative, parents were included in analyses. Rates of paternal, maternal, and double orphanhood among children with one or both parents HIV-positive were respectively 6, 8, and 17 times higher than for children with HIV-negative parents. Around 50% of children living apart from both parents had a grandparent as their guardian; for most of the rest the guardian was an aunt, uncle, or sibling. There were no child-headed households. Almost all children aged 6-14 were attending primary school. There was no evidence that parental HIV affected primary school attainment among children <15 years old. Children of HIV-positive parents were less likely to have attended secondary school than those of HIV-negative parents. The extended family has mitigated the impact of orphanhood on children, but interventions to reduce the incidence of orphanhood, and/or which strengthen society's ability to support orphans, are essential, especially as the HIV epidemic matures and its full impact is felt.

HIV epidemic trend and antiretroviral treatment need in Karonga District, Malawi.

We describe the development of the HIV epidemic in Karonga District, Malawi over 22 years using data from population surveys and community samples. These data are used to estimate the trend in HIV prevalence, incidence and need for antiretroviral treatment (ART) using a simple mathematical model. HIV prevalence rose quickly in the late 1980s and early 1990s, stabilizing at around 12% in the mid-1990s. Estimated annual HIV incidence rose quickly, peaking in the early 1990s at 2.2% among males and 3.1% among females, and then levelled off at 1.3% among males and 1.1% among females by the late 1990s. Assuming a 2-year eligibility period, both our model and the UNAIDS models predicted 2.1% of adults were in need of ART in 2005. This prediction was sensitive to the assumed eligibility period, ranging from 1.6% to 2.6% if the eligibility period was instead assumed to be 1.5 or 2.5 years, respectively.

HIV prevalence and sexual behaviour changes measured in an antenatal clinic setting in northern Tanzania.

OBJECTIVES: To assess the feasibility of collecting sexual behaviour data during HIV surveillance in antenatal care (ANC) clinics, and to establish whether these data can provide information about the correlates of HIV infection in this population. METHODS: Sexual behaviour surveys were conducted in the context of two HIV sentinel surveillance rounds in 11 ANC clinics in north west Tanzania between 2000 and 2002. Responses of individual women were anonymously linked to their HIV status. Three clinic catchment areas overlapped with a community based longitudinal study, which provided independent estimates of HIV prevalence and sexual behaviour. Changes between rounds and differentials between clinics were assessed and a two level logistic regression model used to identify behavioural and contextual correlates of HIV in 3689 women under 25 years of age. RESULTS: Women attending clinics were willing to participate in the study. The sexual behaviour data obtained were internally consistent and tallied reasonably well with sexual behaviour data collected in the community overlapping the clinic catchment. Clear relations emerged between HIV infection and measures of sexual exposure: OR 1.20 (95% CL 1.12 to 1.28) for each year of premarital exposure and 1.09 (1.04 to 1.16) for each year after first marriage; background prevalence OR 1.15 (1.04 to 1.26) associated with each percentage point increase in background prevalence at the clinic; and certain partnership variables such as partner's age OR 0.58 (0.45 to 0.76) if partner less than 10 years older. CONCLUSION: Conducting sexual behaviour surveys in the context of ANC clinics surveillance is feasible and yields useful data.