Role of widows in the heterosexual transmission of HIV in Manicaland, Zimbabwe, 1998-2003

BACKGROUND

AIDS is the main driver of young widowhood in southern Africa.

METHODS

The demographic characteristics of widows, their reported risk behaviours and the prevalence of HIV were examined by analysing a longitudinal population-based cohort of men and women aged 15-54 years in Manicaland, eastern Zimbabwe. The results from statistical analyses were used to construct a mathematical simulation model with the aim of estimating the contribution of widow behaviour to heterosexual HIV transmission.

RESULTS

413 (11.4%) sexually experienced women and 31 (1.2%) sexually experienced men were reported to be widowed at the time of follow-up. The prevalence of HIV was exceptionally high among both widows (61%) and widowers (male widows) (54%). Widows were more likely to have high rates of partner change and engage in a pattern of transactional sex than married women. Widowers took partners who were a median of 10 years younger than themselves. Mathematical model simulations of different scenarios of sexual behaviour of widows suggested that the sexual activity of widow(er)s may underlie 8-17% of new HIV infections over a 20-year period.

CONCLUSIONS

This combined statistical analysis and model simulation suggest that widowhood plays an important role in the transmission of HIV in this rural Zimbabwean population. High-risk partnerships may be formed when widowed men and women reconnect to the sexual network.

The role of testing and counselling for HIV prevention and care in the era of scaling-up antiretroviral therapy

OBJECTIVE

HIV Testing and Counselling (TC) programmes are being scaled-up as part of efforts to provide universal access to antiretroviral treatment (ART).

METHODS AND FINDINGS

Mathematical modelling of TC in Zimbabwe shows that if universal access is to be sustained, TC must include prevention counselling that enables behaviour change among infected and uninfected individuals. The predicted impact TC is modest, but improved programmes could generate substantial reductions in incidence, reducing need for ART in the long-term.

CONCLUSIONS

TC programmes that focus only on identifying those in need of treatment will not be sufficient to bring the epidemic under control.

Discrepancies between UN models and DHS survey estimates of maternal orphan prevalence: insights from analyses of survey data from Zimbabwe

OBJECTIVES

Model-based estimates of maternal (but not paternal) orphanhood are higher than those based on data from demographic and health surveys (DHS). We investigate the consistency of reporting of parental survival status in data from Manicaland, Zimbabwe.

METHODS

We compared estimates of paternal and maternal orphan prevalence in three rounds of a prospective household census in Manicaland (1998-2005) with estimates from DHS surveys and UNAIDS model projections. We investigated the consistency of reporting of parental survival status across the three rounds and compared estimates of adult mortality from the orphan data with direct estimates from concurrent follow-up of a general population cohort. Qualitative data were collected on possible reasons for misreporting.

RESULTS

Paternal and maternal orphan prevalence is increasing in Zimbabwe. Mothers reported as deceased in round 1 of the Manicaland survey were more likely than fathers to be reported as alive in rounds 2 or 3 (33.3% vs 13.4%). This pattern was most apparent among younger children. The qualitative findings suggest that foster parents sometimes claim adopted children as their natural children.

CONCLUSIONS

These results are consistent with misreporting of foster parents as natural parents. This appears to be particularly common among foster mothers and could partly explain the discrepancy between mathematical model and DHS estimates of maternal orphanhood.

Behaviour change in generalised HIV epidemics: impact of reducing cross-generational sex and delaying age at sexual debut

BACKGROUND

Sexual behavioural change is essential to prevent HIV infections in Africa and statistical analysis of risk factors at the individual-level may be used to design interventions. The importance of reducing cross-generational sex (young women having sex with older men) and delaying age at first sex on the spread of HIV at the population-level has been presumed but not scientifically investigated and quantified.

METHODS

A mathematical model of heterosexual spread of HIV was developed to predict the population-level impact of reducing cross-generational sex and delaying sexual debut.

RESULTS

The impact of behaviour change on the spread of HIV is sensitive to the structure and reaction of the sexual network. Reducing cross-generational sex could have little impact on the risk of infection unless it is accompanied by a reduction in the number of risky sexual contacts. Even peer-to-peer sexual mixing can support high endemic levels of HIV. The benefit of delaying sexual debut is comparatively small and is reduced if males continue to prefer young partners or if young women spend more time unmarried. In Manicaland, Zimbabwe, if older men were to use condoms as frequently as young men, the reduction in risk of infection could exceed that generated by a two-year delay in first sex.

CONCLUSIONS

At the individual-level avoiding sex with older partners and delaying sexual debut can decrease the risk of infection but at the population-level these interventions may do little to limit the spread of HIV without wider-ranging behavioural changes throughout the sexual network.

Criteria for detecting and understanding changes in the risk of HIV infection at a national level in generalised epidemics

Identification of causes of changes in prevalence and incidence of HIV at a national level is important for planning future prevention and intervention needs. However, the slow progression to disease and the sensitive and stigmatising nature of the associated behaviours can make this difficult. Changing rates of incidence are to be expected as an epidemic progresses, but separating background changes from those brought about by changes in behaviour and interventions requires careful analysis. This paper discusses the criteria required to determine whether observed changes in HIV prevalence are the result of changes in behaviour.

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.

HIV prevalence and trends from data in Zimbabwe, 1997-2004

BACKGROUND

This paper brings together data from a variety of reports to provide a basis for assessing future steps for responding to and monitoring the HIV epidemic in Zimbabwe.

METHOD

Data reported from four antenatal clinic (ANC) surveys conducted between 2000 and 2004, two small local studies in Zimbabwe conducted from 1997 through 2003, four general population surveys from 1999 through 2003, and service statistics covering 1990 through 2004 were used to describe recent trends in HIV prevalence and incidence, behaviour change, and programme provision.

RESULTS

HIV prevalence among pregnant women attending ANCs declined substantially from 32.1% in 2000 to 23.9% in 2004. The local studies confirmed the decline in prevalence. However, prevalence continued to be high. Sexual behaviour data from surveys suggests a reduction in sexual experience before age 15 years among both males and females age 15-19 years, and in the proportions of males and females aged 15-29 years reporting non-regular sexual partners in the past 12 months. Reported condom use with non-regular partners has been high since 1999. Condom distribution and HIV counseling and testing increased from 2000 to 2004.

DISCUSSION

On the basis of examination of data from a variety of sources, the recent decrease in HIV prevalence may be related to recent reductions in early-age sexual activity and non-regular sexual partnerships and increases in condom use. Comparison of data from sentinel surveillance systems, population based serosurveys, local studies, and service statistics provide increased confidence that a decline in HIV prevalence in Zimbabwe is actually happening in the population.

Declines in HIV prevalence can be associated with changing sexual behaviour in Uganda, urban Kenya, Zimbabwe, and urban Haiti

OBJECTIVE

To determine whether observed changes in HIV prevalence in countries with generalised HIV epidemics are associated with changes in sexual risk behaviour.

METHODS

A mathematical model was developed to explore the relation between prevalence recorded at antenatal clinics (ANCs) and the pattern of incidence of infection throughout the population. To create a null model a range of assumptions about sexual behaviour, natural history of infection, and sampling biases in ANC populations were explored to determine which factors maximised declines in prevalence in the absence of behaviour change. Modelled prevalence, where possible based on locally collected behavioural data, was compared with the observed prevalence data in urban Haiti, urban Kenya, urban Cote d'Ivoire, Malawi, Zimbabwe, Rwanda, Uganda, and urban Ethiopia.

RESULTS

Recent downturns in prevalence observed in urban Kenya, Zimbabwe, and urban Haiti, like Uganda before them, could only be replicated in the model through reductions in risk associated with changes in behaviour. In contrast, prevalence trends in urban Cote d'Ivoire, Malawi, urban Ethiopia, and Rwanda show no signs of changed sexual behaviour.

CONCLUSIONS

Changes in patterns of HIV prevalence in urban Kenya, Zimbabwe, and urban Haiti are quite recent and caution is required because of doubts over the accuracy and representativeness of these estimates. Nonetheless, the observed changes are consistent with behaviour change and not the natural course of the HIV epidemic.

HIV infection and reproductive health in teenage women orphaned and made vulnerable by AIDS in Zimbabwe

AIDS has increased the number of orphans and vulnerable children (OVCs) in sub-Saharan Africa who could suffer detrimental life experiences. We investigated whether OVCs have heightened risks of adverse reproductive health outcomes including HIV infection. Data on HIV infection, sexually transmitted infection (STI) symptoms and pregnancy, and common risk factors were collected for OVCs and non-OVCs in a population survey of 1523 teenage children in eastern Zimbabwe between July 2001 and March 2003. Multivariate logistic regression was used to test for statistical association between OVC status, adverse reproductive health outcomes and suspected risk factors. Amongst women aged 15-18 years, OVCs had higher HIV prevalence than non-OVCs (3.2% versus 0.0%; p = 0.002) and more common experience of STI symptoms (5.9% versus 3.3%; adjusted odds ratio = 1.75, 95% CI 0.80-3.80) and teenage pregnancy (8.3% versus 1.9%; 4.25, 1.58-11.42). OVCs (overall), maternal orphans and young women with an infected parent were more likely to have received no secondary school education and to have started sex and married, which, in turn, were associated with poor reproductive health. Amongst men aged 17-18 years, OVC status was not associated with HIV infection (0.5% versus 0.0%; p = 1.000) or STI symptoms (2.7% versus 1.6%; p = 0.529). No association was found between history of medical injections and HIV risk amongst teenage women and men. High proportions of HIV infections, STIs and pregnancies among teenage girls in eastern Zimbabwe can be attributed to maternal orphanhood and parental HIV. Many of these could be averted through further female secondary school education. Predicted substantial expanded increases in orphanhood could hamper efforts to slow the acquisition of HIV infection in successive generations of young adults, perpetuating the vicious cycle of poverty and disease.

Patterns of uptake of treatment for self reported sexually transmitted infection symptoms in rural Zimbabwe

OBJECTIVES

To determine the extent of self reported symptoms perceived to be related to sexually transmitted infections and the patterns of subsequent treatment seeking behaviour in a predominantly rural population of Zimbabwe.

METHODS

A population based survey of 4331 men and 5149 women was conducted in rural Zimbabwe during 1998-2000. Structured confidential interviews collected data on self reported sexually transmitted infection symptoms, treatment seeking behaviour, sociodemographic characteristics, and sexual behaviour.

RESULTS

25% of men aged 17-54 years report experiencing genital sores and 25% of men report experiencing urethral discharge; 30% of women aged 15-44 years report experiencing vaginal discharge. The lifetime number of sexual partners, age, and years of sexual activity were all significant predictors of symptoms for both men and women (all p values <0.001). 92% of men and 62% of women had sought treatment for their symptoms in the past year (p value <0.001). Men and women were equally likely to have sought treatment at a local hospital or clinic, but women were much less likely than men to have sought treatment at a different hospital or clinic. Among those who had sought treatment, men sought treatment faster than women and were more likely to report being "very satisfied" with their treatment than women.

CONCLUSIONS

The gender differences in treatment seeking are of major concern for control efforts and further work on determining the reasons for these should be a priority. This would inform the likely impact of both increasing availability of local services and further reducing the stigma faced by those wishing to access such services.

Informal confidential voting interview methods and temporal changes in reported sexual risk behaviour for HIV transmission in sub-Saharan Africa

OBJECTIVES

Reliable data on sexual behaviour trends are needed to evaluate HIV interventions in sub-Saharan Africa but are difficult to obtain due inter alia to social desirability bias. The objective of this paper is to assess whether the use of informal confidential voting interviews (ICVI) was associated with greater reporting of socially proscribed behavioural risk factors for HIV infection than were conventional interviewing methods.

METHODS

Comparison of changes in reports of risk behaviours for HIV infection in ICVI versus face to face interviews (FTFIs) between the first two rounds of a large scale, longitudinal, population based survey in Manicaland, Zimbabwe. Examination of factors that could contribute to observed changes in the effect of ICVI, including temporal changes in response error and social desirability, and factors affecting statistical power to detect differences between methods-that is, reductions in the prevalence of risk behaviours and sample size.

RESULTS

Enhanced reporting of HIV associated risk behaviours in ICVI interviews was not so apparent in the second round as in the first round of the survey, particularly for less frequently reported behaviours. Levels of reported HIV associated risk behaviour and sample sizes both declined between the two survey rounds. The level of response error was higher in ICVI interviews than in FTFI interviews but did not alter over time.

CONCLUSION

ICVI interviews can reduce social desirability bias in data on HIV associated risk behaviours. The extent and direction of change in net reduction in bias over time remains uncertain and will depend on local circumstances.

Chlamydia trachomatis in symptomatic and asymptomatic men: detection in urine by enzyme immunoassay

BACKGROUND

Infection with Chlamydia trachomatis is known to be a common cause of urethritis and cervicitis. The standard methods of detection require the collection of intra-urethral and/or cervical swabs, which may be submitted for culture, antigen detection or nucleic acid amplification. The collection of swabs is suitable only within the context of a health care facility. Recent reports have indicated that antigen detection can be used with urine specimens, and because these can be self-collected, this may be particularly useful for the detection of asymptomatic carriage.

OBJECTIVE

To determine the sensitivity and specificity of urine antigen assays in the detection of chlamydial infection in men.

SETTING

Two groups of men were investigated; men with urethritis attending clinics or private practitioners, and healthy adult men enrolled into either urban or rural HIV prevention projects.

METHODS

Urine samples from men in both groups were collected and assayed for the presence of chlamydial antigen using a commercial enzyme immunoassay (EIA) kit. For symptomatic men an intra-urethral swab was also collected and assayed for antigen detection using a commercial EIA. For asymptomatic men, a ligase chain reaction was carried out on the same urine sample.

RESULTS

The prevalence of chlamydial antigen in symptomatic men was 15% (39/257), and in asymptomatic men was 4% (15/349). The sensitivity and specificity of urine EIA for symptomatic men was 87% and 83% respectively. For asymptomatic men, the sensitivity of urine EIA was 86%, and the specificity was 100%.

CONCLUSION

Urine EIA is a relatively inexpensive method for the detection of chlamydial infections in men. The true specificity in symptomatic men may be higher, as the "gold standard" that we used may give false negative results. Antigen EIA for examination of urine specimens from community surveys of asymptomatic men may be particularly useful because of the low cost of assays, and because urine samples can be self-collected without discomfort to study subjects. The prevalence of C. trachomatis that we describe here is consistent with other studies of chlamydial epidemiology in Zimbabwe.

A rural HIV epidemic in Zimbabwe? Findings from a population-based survey

The aim of the study was to use population-based data from 689 adults to describe the socio-demographic, behavioural and biomedical correlates of HIV infection and aid identification of effective HIV control strategies for rural Zimbabwe. Dried blood spot and urine samples were collected for HIV and sexually transmitted disease (STD) testing and participants were interviewed on socio-demographic characteristics, sexual behaviour and experience of STD symptoms. HIV seroprevalence was 23.3% and was higher in females, divorcees, widows, working men, estate residents, and respondents reporting histories of STD symptoms. Female HIV seroprevalence rises sharply at ages 16-25. A third of sexually-active adults had experienced STD-associated symptoms but there were delays in seeking treatment. Herpes simplex virus type 2 (HSV-2) and Trichomonas vaginalis are more common causes than syphilis, gonorrhoea, and chlamydia, and are strongly associated with HIV infection. Local programmes promoting safer sexual behaviour and fast and effective STD treatment among young women, divorcees and working men could reduce the extensive HIV transmission in rural communities.

Enzyme immunoassay for urogenital trichomoniasis as a marker of unsafe sexual behaviour

Enzyme immunoassay (EIA) was used to detect antibodies to Trichomonas vaginalis in sera from Zimbabwe. The EIA showed a sensitivity of 95 and 94% when compared with vaginal swab culture among women attending a family planning clinic (FPC) and female commercial sex workers (CSW) respectively. The specificity was 85 and 77% in the two groups. Culture-negative FPC women were sub-divided into high risk or low risk of exposure to trichomoniasis. The seroprevalence was 10% (6/61) among low risk women, 21% (10/48) among high risk women and 23% (9/39) among culture negative CSW. The EIA was positive in 46% (18/39) men with genital discharge but only 5% (2/37) healthy blood donors. None of 31 sera from prepubescent children was positive. The EIA may be useful for community surveys of trichomoniasis. Because T. vaginalis is a common sexually transmitted disease, the test may indicate behaviour that increases the risk of STD transmission.

The effectiveness of HIV prevention and the epidemiological context

Planning an intervention to prevent infections with the human immunodeficiency virus (HIV) should be guided by local epidemiological and socioeconomic conditions. The socioeconomic setting and existing public service capacity determine whether an intervention can have a significant outcome in terms of a reduction in a defined risk. The epidemiological context determines whether such risk reduction translates into a measurable impact on HIV incidence. Measurement of variables describing the epidemiological context can be used to determine the local suitability of interventions, thereby guiding planners and policy-makers in their choice of intervention. Such measurements also permit the retrospective analysis of the impact of interventions where HIV incidence was not recorded. The epidemiological context is defined for four different categories of intervention, shown to be effective in lower-income countries by randomized controlled trials. Appropriate indicators for the epidemiological context and methodological guidelines for their measurement are proposed. Their use in the transfer of a successful intervention from one context to another and in scaling up the effort to control HIV infection is explored. These indicators should provide a useful resource for those involved in planning HIV prevention interventions.

Adjusting ante-natal clinic data for improved estimates of HIV prevalence among women in sub-Saharan Africa

OBJECTIVES

To find a simple and robust method for adjusting ante-natal clinic data on HIV prevalence to represent prevalence in the general female population in the same age range, allowing for fertility differences by HIV status.

BACKGROUND

HIV prevalence comparisons for pregnant women and women in the general community show that prevalence in the latter is significantly higher than in the former. An adjustment procedure is needed that is specific for the demographic and epidemiological circumstances of a particular population, making maximum use of data that can easily be collected in ante-natal clinics or are widely available from secondary sources.

METHODS

Birth interval length data are used to allow for subfertility among HIV-positive women. To allow for infertility, relative HIV prevalence ratios for fertile and infertile women obtained in community surveys in populations with similar levels of contraception use are applied to demographic survey data that describe the structure of the population not at risk of child-bearing.

RESULTS

For populations with low contraception use, the procedure yields estimates of general female HIV prevalence of 35-65% higher than the observed ante-natal prevalence, depending on population structure. Results were verified using general population prevalence data collected in Kisesa (Tanzania) and Masaka (Uganda). For high contraception use populations, adjusted values range from 15% higher to 5% lower, but only limited verification has been possible so far.

CONCLUSIONS

The procedure is suitable for estimating general female HIV prevalence in low contraception use populations, but the high contraception variant needs further testing before it can be applied widely.

Apostles and Zionists: the influence of religion on demographic change in rural Zimbabwe

Religion has acted as a brake on demographic transition in a number of historical and contemporary populations. In a study in two rural areas of Zimbabwe, we found substantial differences in recent demographic trends between Mission and Independent or "Spirit-type" churches. Birth rates are higher in some Spirit-type churches and, until recently, infant mortality was also higher. Recent increases in mortality were seen within Mission churches but not in Spirit-type churches. Missiological and ethnographic data indicate that differences in religious teaching on healthcare-seeking and sexual behaviour and differences in church regulation could explain this contrast in demographic patterns. More restrictive norms on alcohol consumption and extra-marital relationships in Spirit-type churches may limit the spread of HIV and thereby reduce its impact on mortality. These contrasting trends will influence the future religious and demographic profile of rural populations in Zimbabwe.

Reductions in risk behaviour provide the most consistent explanation for declining HIV-1 prevalence in Uganda

OBJECTIVE

To monitor the HIV-1 epidemic in Western Uganda and the possible impact of interventions.

DESIGN

Results from sentinel surveillance of HIV-1 seroprevalence were compared with cross-sectional serosurvey data and model simulations.

METHODS

Age-specific trends in HIV-1 prevalence between 1991 and 1997 amongst antenatal clinic (ANC) attenders in the town of Fort Portal, where a comprehensive AIDS control programme has been implemented since 1991, were analysed. Results were compared with outputs from a mathematical model simulating the HIV-1 epidemic in Uganda. Two scenarios were modelled: one without and one with behaviour change. Sentinel surveillance data were compared with data from a population-based HIV-1 serosurvey at the study site, which was carried out in early 1995.

RESULTS

Data from 3271 ANC attenders identified greater education and being single as risk factors for HIV-1 infection. A significant decrease of risk for women with secondary school education over time was observed, whereas the risk for illiterate women remained high. Among women aged 15-19 years (n = 1045) education and marital status-adjusted HIV-1 prevalence declined steadily from 32.2% in 1991 to 10.3% in 1997. For 20-24-year-old women (n = 1010) HIV-1 prevalence increased until 1993 from 19.9% to 31.7% and decreased thereafter (21.7% in 1997). These trends closely follow the prediction of the model simulation assuming behaviour change, and for 1995-1997, confidence intervals of the HIV-1 prevalence estimate exclude the model output for an uninfluenced epidemic. No clear trends of HIV-1 prevalence were found in older women (n = 1216) and comparisons with the model were ambiguous. Sentinel surveillance data at the time of the population survey closely reflected results for the female general population sample for the two younger age-groups (15-19 and 20-24 years). In contrast, pregnant women aged 25-29 years showed significantly lower rates than the population sample (20.8% versus 45.1%).

CONCLUSION

HIV-1 prevalence amongst ANC attenders aged 15-24 years can be used to monitor the HIV-1 epidemic in the given setting. Declining trends of HIV-1 prevalence in women aged 15-19 and 20-24 years most likely correspond to a reduced HIV-1 incidence attributable to changes in behaviour. Our data also show that sentinel surveillance data need to be age-stratified to give useful information.

Estimating HIV incidence from age-specific prevalence data: comparison with concurrent cohort estimates in a study of male factory workers, Harare, Zimbabwe

OBJECTIVE

To compare HIV incidence estimates from cross-sectional age-specific prevalence data with concurrent cohort estimates and to examine the sensitivity of the estimates to changes in age-categorization and survivorship assumptions.

METHODS

Two previously described methods of estimating HIV incidence from cross-sectional prevalence data - the cumulative incidence and survival (CIS) and constant prevalence (CP) methods - are applied using data from a study of male factory workers in Harare, Zimbabwe. The methods are applied under two alternative groupings of the HIV prevalence data and under alternative survivorship assumptions: (a) Weibull distribution providing the best fit to the HIV prevalence data using the CIS method; (b) Weibull distribution matching data from an HIV natural history cohort study in Uganda; and (c) survivorship pattern as in (b) with survival periods reducing with increasing age at infection. Age-specific, age-standardized and cumulative HIV incidence estimates are calculated. The results are compared with concurrent longitudinal estimates from 3 years of follow-up of the Harare cohort (1993-1995).

RESULTS

Age-standardized HIV incidence was estimated at 2.02 per 100 man years (95% CI, 1.57-2.47) in the cohort study. There was evidence of recent variability in HIV incidence in these data. Estimates from the cross-sectional methods ranged from 1.98 to 2.74 per 100 man years and were sensitive to changes in age-categorization of the HIV prevalence data and changes in survivorship assumptions. The cross-sectional estimates were higher at central ages and lower at older ages than the cohort estimates. The age-specific estimates from the CIS method were less sensitive to changes in age grouping than those from the CP method.

CONCLUSIONS

HIV incidence remains high in Harare. Incidence estimates broadly consistent with cohort estimates can be obtained from single-round cross-sectional HIV prevalence data in established epidemics - even when the underlying assumption of stable endemic prevalence is not fully met. Estimates based on cross-sectional surveys should therefore be explored when reliable longitudinal estimates cannot be obtained. More data on post-HIV infection survivorship distributions in sub-Saharan Africa would facilitate the improvement of estimates of incidence based on cross-sectional surveys.

Measuring the impact of HIV on fertility in Africa

OBJECTIVES

To review evidence for the impact of HIV on fertility from empirical sources pertaining to African populations and to discuss the implications for surveillance based on antenatal clinic populations.

METHODS

The theoretical equivalence between the fertility rate ratio for HIV-positive to HIV-negative women and the relative odds of being infected for pregnant women compared with the general female population is demonstrated. This equivalence is used to compare fertility differentials measured in cohort studies with those calculated indirectly from antenatal clinic data. Data from case-control studies and theoretical predictions from a model of the proximate determinants of fertility and HIV incidence are used to obtain plausible explanations of the fertility differences. Estimates of population attributable change are made.

RESULTS

Fertility of HIV-positive women is lower than that of HIV-negative women, in all but the youngest age-group, and the differential increases with women's age and epidemic duration. Selection for early start of sexual activity explains the reverse pattern at younger ages. Lower fertility amongst HIV-positive women causes a population attributable decline in total fertility of the order of 0.4% for each percentage point HIV prevalence in the general female population.

CONCLUSIONS

In populations that do not use contraceptives, HIV-positive women have lower fertility principally as a result of foetal losses consequent to infection with HIV and coinfection with other sexually transmitted diseases; behavioural factors tend to enhance this differential. Other factors being equal, HIV prevalence estimates based on antenatal surveillance underestimate true prevalence in women in the childbearing years.

Is there evidence for behaviour change in response to AIDS in rural Zimbabwe?

This article reports on evidence for behaviour change in response to AIDS among women in two rural areas of Manicaland Province, Zimbabwe. It examines self-reported data on two overlapping areas of behaviour: (1) actions taken to avoid HIV-1 infection; and (2) fertility practices. The latter were used to assess the validity of the former, given that self-reported behaviour data are notoriously problematic. It is concluded that while self-reported behaviour change is exaggerated, the true level of change has nonetheless been significant and includes delayed onset of sexual relations, increased use of condoms and, possibly, increased monogamy. Reported actions taken to avoid HIV-1 infection and differentials in fertility practices were correlated with data on demographic, social and psychological factors. Differentials in fertility practices were associated with heightened risk perception--particularly when based on personal acquaintance with AIDS patients--but not with greater knowledge of HIV-1/AIDS. Results from the study suggest that effective behaviour change in Manicaland is facilitated by greater knowledge, experience and personal risk perception but obstructed by low female autonomy, marital status and economic status, and by male labour migration and alcohol consumption. Gaps in knowledge included misconceptions about the distinction between HIV-1 and AIDS, the influence of STDs, perinatal transmission, and incorrect modes of transmission. Better knowledge was associated with education, religion, travel and media exposure Personal risk perception was quite high (42%) and correlated with non-marriage, media exposure and contact with medical services. Few respondents knew close relatives with HIV/AIDS (4%) but nearly a quarter of those who felt in danger of infection said this was because friends and relatives were dying of AIDS. Many reported credible behavioural responses, some of which would only be effective given their partner's co-operation. Intensified behaviour interventions are needed which should include peer-education initiatives targeting men and individuals without access to modern media. The epidemic may accelerate fertility decline in rural Zimbabwe through behavioural as well as biological change.

Recent upturn in mortality in rural Zimbabwe: evidence for an early demographic impact of HIV-1 infection?

OBJECTIVES

To describe recent mortality trends in rural Zimbabwe and to assess the impact of HIV-1 infection.

METHOD

Comparative, cross-sectional, retrospective, demographic survey with 1-year follow-up. Parallel HIV-1 surveillance. Comparison of results with 1992 national census and vital registration data and results from mathematical model-based population projections.

SETTING AND PARTICIPANTS

Residents of 929 (745 revisited in 1995) households in two rural areas of Manicaland Province, Zimbabwe, with contrasting HIV-1 prevalence: Honde and Rusitu valleys. Subjects gave information on parental survival for 2320 resident children. Female residents aged 13-49 years (n = 1237) provided information on birth histories and child survival. Consenting women attending local antenatal clinics (n = 487) provided blood samples for HIV-1 screening and demographic information.

MAIN OUTCOME MEASURES

HIV-1 prevalence in pregnant women; per capita death registration rates; incidence of parental death for children aged under 8 years; infant mortality and age-specific death probabilities.

RESULTS

HIV-1 prevalence was high in each study area. Death registration and age-specific mortality have begun to rise. The largest increases were seen in the area of higher HIV-1 prevalence (Honde) and among younger adults, particularly men. Incidence of parental death was observed to be rising. Increases in registered deaths were concentrated among HIV-1-associated causes.

CONCLUSIONS

The observed increases in mortality by age, sex and cause of death were consistent with those expected early in a severe HIV-1 epidemic, on the basis of mathematical model projections and observations elsewhere in Africa. Further rises in mortality, particularly among women and young children, and consequent increases in orphanhood, are to be expected in rural areas of Zimbabwe.

Demographic approaches to the estimation of incidence of HIV-1 infection among adults from age-specific prevalence data in stable endemic conditions

OBJECTIVE

To develop methods for estimating the incidence of HIV-1 infection among adults from age-specific prevalence data derived in stable endemic conditions.

METHODS

Two methods are proposed. The first method is the Cumulative Incidence and Survival Method which treats HIV-1 prevalence at any given age as the cumulative incidence of new infections at each preceding age, adjusted for mortality. A model for age-specific incidence is fitted to the data using maximum likelihood techniques. The other method is the Constant Prevalence Method whereby the incidence of new infections within a time interval (t-r, t) is calculated as the difference, after adjusting for mortality, between observed prevalence levels at two successive age intervals, whose mean ages are r years apart. The two methods were applied to data from Kampala, Uganda.

RESULTS

Plausible estimates of age-specific and cumulative HIV-1 incidence were obtained from each of the methods. Estimates of HIV-1 incidence are sensitive to assumptions regarding the length of the survival period after infection and the stability of the epidemic.

CONCLUSIONS

Reasonable estimates of HIV-1 incidence can be obtained from prevalence data derived in near-stable conditions. With the Constant Prevalence Method, these conditions may be relaxed if large sample sizes are available and age-reporting is good. The methods proposed could be used in the design and implementation of HIV-1 prevention trials. Cumulative incidence is a better indication of demographic impact than average age-specific incidence.

Age and religion selection biases in HIV-1 prevalence data from antenatal clinics in Manicaland, Zimbabwe

Sera from 487 women attending antenatal clinics in two areas of Manicaland were tested for the presence of HIV-1 infection. In the Honde Valley and Rusitu Valley areas, 24,3 pc and 14 pc respectively, were found to be infected. HIV-1 infection was found to be associated with age, marital status and location. Younger women, non-married women and women living in the Honde Valley were all more likely to be infected. There was also a weak association with level of education, with women with secondary education being at greater risk of being infected. The unadjusted overall figures for HIV-1 prevalence from the antenatal clinics were shown to provide a poor indication of the relative levels of prevalence of infection in the two study areas because of differences in the age structure and religious affiliations of the antenatal clinic and study populations. Similar problems may exist in sentinel surveillance data and would distort comparisons between locations and over time, especially during periods of rapid fertility change. In particular, the age bias is liable to exaggerate differences between urban and rural populations in developing societies. Where comparable information is available for the general population and sample sizes permit, this problem may be overcome by collecting basic socio-demographic data on the individuals tested and then applying standardization techniques. In the Honde Valley and Rusitu Valley example, the levels of HIV-1 prevalence after adjusting for age differences are 18,4 pc and 13,2 pc respectively.

Orphan prevalence and extended family care in a peri-urban community in Zimbabwe

An orphan enumeration survey was conducted in 570 households in and around Mutare, Zimbabwe in 1992; 18.3% (95% CI 15.1-21.5%) of households included orphans. 12.8% (95% CI 11.2-14.3%) of children under 15 years old had a father or mother who had died; 5% of orphans had lost both parents. Orphan prevalence was highest in a peri-urban rural area (17.2%) and lowest in a middle income medium density urban suburb (4.3%). Recent increases in parental deaths were noted; 50% of parental deaths since 1987 could be ascribed to AIDS. Orphan household heads were likely to be older and less well-educated than non-orphan household heads. The majority of orphaned children were being cared for satisfactorily within extended families, often under difficult circumstances. Caregiving by maternal relatives represents a departure from the traditional practice of caring for orphans within the paternal extended family and an adaptation of community-coping mechanisms. There was little evidence of discrimination or exploitation of orphaned children by extended family caregivers. The fact that community coping mechanisms are changing does not imply that extended family methods of caring are about to break down. However, the emergence of orphan households headed by siblings is an indication that the extended family is under stress. Emphasis needs to be placed upon supporting extended families by utilizing existing community-based organizations. Orphan support programmes may need to be established initially in high risk communities such as low-income urban areas and peri-urban rural areas.

Is HIV-1 likely to become a leading cause of adult mortality in sub-Saharan Africa?

Concerns are sometimes expressed at the extent to which HIV-1 is prioritized within international and national health budgets and as a research issue, on the grounds that much larger numbers of people in developing countries currently die from other diseases, such as malaria and tuberculosis. We use a previously described mathematical model to explore how the HIV-1 epidemic could develop within a sub-Saharan African context and investigate the trends and patterns of adult mortality which could follow. Two contrasting scenarios are studied, one which turns population growth rates negative and another which does not. In both cases, HIV-1-related disease accounts for over 75% of annual deaths among men and women aged 15-60 years by year 25 of the epidemic. Relatively little change in mortality is seen in the early years of the simulated epidemics. However, by year 15, expectation of life at age 15 has fallen from 50 to below 30 years. The fragmentary evidence now available from empirical studies supports the impression that HIV-1 is rapidly emerging as a leading cause of adult deaths in areas of sub-Saharan Africa. Observed patterns of age-dependent mortality reflect those projected in the model simulations.

Determinants of the demographic impact of HIV-1 in sub-Saharan Africa: the effect of a shorter mean adult incubation period on trends in orphanhood

Recent evidence suggests that the adult HIV-1 incubation period may be shorter in some sub-Saharan African populations than in Western populations. In this article we use mathematical-model-based simulations to show that, other things being equal, a shorter incubation period can result in smaller but more pronounced HIV-1 epidemics and faster, more acute, changes in demographic features, such as adult mortality, orphanhood and population structure. Empirical studies of orphanhood reveal similar patterns to those found in the simulations, but suggest that migration patterns and structural factors can give rise to greater concentrations of orphans in areas of relatively low HIV-1 prevalence.

Attitudes towards donor insemination--a post-Warnock survey

In a multi-centred study, a total of 799 patients, donors and health-care professionals concerned with artificial insemination with donor semen (AID) responded to a questionnaire regarding their attitudes towards current provision of AID services and proposed legislation. There was little support for any fundamental change in the way in which AID is practised, at least in those centres. The anonymous status of the donor met with universal agreement. Although there was some support for the communication of non-identifying details to the recipient couple, where they wanted them, there was no support for any legislation which might give the AID child a right of access to details of the donor. The greatest divergence of opinion was over the question of who should have access to AID treatment and whether or not screening procedures should be applied to prospective parents. Most respondents felt that the closed and confidential relationship between the clinic and the other parties involved should not automatically be extended to general practitioners or any national bodies. In respect of specific recommendations of the Warnock Committee, there was support for changes which might legitimize or assist the present system, but not for any which might be restrictive.

Who has a vasectomy reversal?

The characteristics of the first 200 cases of vasectomy reversal have been analysed. The mean time from vasectomy to reversal was 4.8 years. It varied according to the reason for requesting reversal, and was particularly short when the operation had been performed at the time of the partner's pregnancy. Thirty percent of the men were with the same partner and 70% a new partner. Vasectomy reversal cases tended to be younger than vasectomy patients as a whole but did not differ significantly in social class. In this series of reversals, spermatozoa were present in the ejaculate throughout the 20-week follow-up time in 80% of the men; the pregnancy rate was 44%.

New applications of sporopollenin as a solid phase support for peptide synthesis and the use of sonic agitation

The synthesis of a tetrapeptide on a base functionalised sporopollenin using sonic agitation for coupling and washing processes is described.