HIV prevalence and incidence in rural Tanzania: results from 10 years of follow-up in an open-cohort study

Unmet need for modern contraception by HIV status: findings from community-based studies implemented before and after earlier ART initiation program in rural Tanzania

BACKGROUND

Tanzania Health policy insists on the need to provide all women access to contraception despite HIV status. We used data from two HIV epidemiologic serological surveys carried out at different periods of ART provision in rural Tanzania to assess the level of unmet need for modern contraception by HIV status and associated factors.

METHODS

We performed secondary data analysis of two surveys conducted at the Magu Health and Demographic Surveillance System site, in Mwanza, Tanzania. Information on unmet need for modern contraception was derived from fertility desire and contraception use. Unmet need, HIV status, and socioeconomic and demographic variables were analysed. The percentage of women with unmet needs for modern contraception by HIV status is presented for the 2012 and 2017 surveys. Bivariate and multivariate analyses using logistic regression were used to investigate associated factors showing adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs).

RESULTS

Data from 3352 and 3196 women aged 15-49 years collected in the 2012 and 2017 surveys, respectively, were analysed. The percentages of women with unmet needs for modern contraception in the 2012 and 2017 surveys were 30.9% (95% CI 29.4-32.6) and 31.6% (95% CI 30.0-33.3), respectively. The unmet need for modern contraception was 26% lower in HIV-uninfected women in 2012 (aOR = 0.74; 95% CI 0.569-0.973); p = 0.031). Risk factors for unmet need for modern contraception in 2012 were HIV uninfected (adjusted OR = 0.74; 95% CI 0.569-0.973); p = 0.031), married marital status (adjusted OR = 0.768; 95% CI 0.743-0.794); p < 0.0001), higher education (adjusted OR = 0.768; 95% CI 0.743-0.794); p < 0.0001), and taking alcohol (adjusted OR = 0.768; 95% CI 0.743-0.794); p < 0.0001). Only two factors were associated with unmet need for modern contraception in 2017: married marital status (adjusted OR = 0.46; 95% CI 0.305-0.722); p = 0.001) and women who earned for their families (aOR = 0.66; 95% CI 0.494-0.887); p = 0.006).

DISCUSSION

Nearly one-third of women had an unmet need for modern contraception, which was lower in HIV-uninfected women than in WLHIV-infected women. The study has identified women whose demand for contraception has not been met: WLHIV, post marital women, women with low education and women who were reported to earn money for their families. Family planning interventions should be tailored to these groups of women.

Fertility trends by HIV status in a health and demographic surveillance study in Magu District, Tanzania, 1994-2018

BACKGROUND

Sub-Saharan Africa (SSA) has the highest fertility rates and highest HIV disease burden globally. However, it is not clear how the rapid expansion of anti-retroviral therapy (ART) for HIV has impacted the fertility gap between HIV-infected and uninfected women. We used data from a Health and Demographic Surveillance System (HDSS) in north-western Tanzania to explore trends in fertility rates and the relationship between HIV and fertility over the 25-year period.

METHODS

From 1994 to 2018, births and population denominators from the HDSS population were used to obtain age-specific fertility rates (ASFRs) and total fertility rates (TFRs). HIV status was extracted from eight rounds of epidemiologic serological surveillances (1994-2017). Fertility rates by HIV status and in different levels of ART availability were compared over time. Independent risk factors for fertility changes were examined using Cox proportional hazard models.

RESULTS

There were 24,662 births from 36,814 women (15-49) who contributed a total of 145,452.5 Person-Years of follow-ups. The TFR declined from 6.5 births per woman in 1994-1998 to 4.3 births per woman in 2014-2018. The number of births per woman was 40% lower in women living with HIV than in HIV-uninfected women (4.4 vs. 6.7), although this difference narrowed over time. The fertility rate in HIV-uninfected women was 36% lower in 2013-2018 than in 1994-1998(age-adjusted HR = 0.641; 95% CI 0.613-0.673). In contrast, the fertility rate in women living with HIV was relatively unchanged over the same follow up period (age-adjusted HR = 1.099; 95% CI 0.870-1.387).

CONCLUSIONS

There was a notable fertility decline among women in the study area from 1994 to 2018. Fertility remained lower in women living with HIV than in HIV-uninfected women, but the difference continued to narrow over time. These results highlight the need for more research into fertility changes, fertility desire and family planning use in Tanzanian rural communities.

No association between fertility desire and HIV infections among men and women: Findings from community-based studies before and after implementation of an early antiretroviral therapy (ART) initiation program in the rural district of North-western Tanzania

Background: Fertility is associated with the desire to have children. The impacts of HIV and antiretroviral therapy (ART) on fertility are well known, but their impacts on the desire for children are less well known in Tanzania. We used data from two studies carried out at different periods of ART coverage in rural Tanzania to explore the relationship between HIV infection and fertility desires in men and women. Methods: We conducted secondary data analysis of the two community-based studies conducted in 2012 and 2017 in the Magu Health and Demographic system site, in Tanzania. Information on fertility desires, HIV status, and social-economic and demographic variables were analyzed. Fertility desire was defined as whether or not the participant wanted to bear a child in the next two years. The main analysis used log-binomial regression to assess the association between fertility desire and HIV infection. Results: In the 2012 study, 43% (95% CI 40.7-45.3) of men and 33.3% (95% CI 31.8 - 35.0) women wanted another child in the next two years. In 2017 the percentage rose to 55.7% (95% CI 53.6 - 57.8) in men and 41.5% (95% CI 39.8 - 43.1) in women. Although fertility desire in men and women were higher in HIV uninfected compared to HIV infected, age-adjusted analysis did not show a statistical significance difference in both studies (2012: PR=1.02, 95%CI 0.835 - 1.174, p<0.915 and 2017: PR = 0.90 95%CI 0.743 - 1.084 p= 0.262). Discussion: One-third of women and forty percent of men desired for fertility in 2012, while forty percent of women and nearly half of men desired for fertility in 2017. The data showed fertility desire, in 2012 and 2017 were not related to HIV infection in both periods of ART coverage.

The prevalence and incidence of HIV in the ART era (2006-2016) in North West Tanzania

Background

Sub-Saharan countries bears a disproportionate percentage of HIV infections and HIV related deaths despite the efforts to strengthen HIV prevention and treatments services, including ART. It is important to demonstrate how these services have contributed to reducing the epidemic using available population data.

Methods

We estimated the prevalence and incidence rates from a cohort running over 23 years in Magu District, Mwanza Region-North West Tanzania. Adults 15 years and over who were residents of the Kisesa observational HIV cohort study between 2006 and 2016 were eligible for inclusion. Survival analysis was used to calculate person-time at risk, incidence rates and 95% confidence intervals (CI). Cox regression models were used for the risk factor analyses disaggregated by sex and age group.

Results

The HIV prevalence in the sero-surveys decreased from 7.2% in 2006/07 to 6.6% in 2016, with a notable decrease of over 50% for both men and women aged 15-24 years. The incidence rate for HIV was estimated to be 5.5 (95% CI 4.6 - 6.6) per 1000 person-years in women compared to 4.6 (95% CI 3.5 – 5.8) in men, with a decrease over time. Despite the availability of ART services, the uptake is still small.

Conclusions

New infections are still occurring, with high HIV incidence in individuals aged below 45 years. With new guidelines and the 95-95-95 UNAIDS target, prevalence and incidence must be adequately assessed. In addition, there is a need for additional efforts to assess the impact of HIV/AIDS prevention programmes and intervention services, especially in these areas where resources are limited.

Social cohesion, social trust, social participation and sexual behaviors of adolescents in rural Tanzania

Background

Social cohesion, defined as a glue holding society together, has been found to influence several aspects of human behavior. Social cohesion, being composed of social trust and social participation, is a social factor that may influence sexual behaviors. Unfortunately, studies investigating the influence of social cohesion on sexual behaviors among young people are scarce. This study examined the influence of social cohesion on safe sexual behavior among adolescents in rural Tanzania.

Methods

A cross-sectional study was conducted among 403 school adolescents of the Newala district, between May and August 2010. Socio-demographic characteristics, social cohesion (social trust and social participation) and sexual behavior (age at sexual debut, intention to use and reported condom use, number of sexual partners) were obtained through self-administered questionnaires. Data analysis was performed using descriptive statistics and binary logistic regression.

Results

Sexual debut at under 13 years of age was reported by 12% of the respondent. A majority (71%) reported multiple sexual partnerships and half of the participants reported to have used a condom at their last sexual encounter. The intention to use a condom was reported by 77% of the respondents. Having multiple sexual partnerships was associated with social trust only (odds ratio: 3.5, 95% CI 1.01–12.3) whereas reported condom use was related with social cohesion (odds ratio 4.8 95% CI 1.66–14.06). Social cohesion, trust or participation was not associated with young age at sexual debut or intention to use a condom. Being a female (odds ratio 2.07 95% CI 1.04–4.12.) was associated with intention to use a condom.

Conclusion

This study indicates that social cohesion and socio-demographic factors influence actual behavior performance and behavioral intentions. The findings point to the importance of collecting more evidence on social cohesion and sexual behaviors in different settings and designing interventions that enhance social cohesion among adolescents in order to reinforce positive sexual behaviors.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-6428-7) contains supplementary material, which is available to authorized users.

Prevalence of self-reported symptoms of sexually transmitted infections, knowledge and sexual behaviour among youth in semi-rural Tanzania in the period of adolescent friendly health services strategy implementation

Background

Global evidence shows that sexually transmitted infections (STIs) prevalence and sexual risk behaviours are high among youth, and knowledge about STIs is low. In Tanzania, there is limited recent evidence regarding these issues. The aim of this study was to describe the health seeking behaviour of youth reporting STI symptoms in semi-rural Tanzania and to evaluate the association of socio-demographic characteristics, STI knowledge and sexual risk behaviour with STI symptom reporting.

Methods

This was a cross-sectional study involving 2251 sexually experienced youth (15–24 years), who participated in a larger baseline survey of a cohort within Ifakara town. Interview data were electronically collected by trained field workers. Logistic regression analysis was used to identify factors that influence the risk of reporting STI symptoms within the past year, using Stata 12.1.

Results

The prevalence of self-reported STI symptoms in the past year was 19.9%. Almost all of youth had heard of STIs and 32.7% of youth could mention at least one sign. 34.4% had sought care for their STI symptoms, the majority at private facilities. Only 20% of HIV-STI co-infected youth was aware of their HIV status.

Youth with more knowledge of STI symptoms reported to have had symptoms more often (OR = 1.28; 95% CI 1.01–1.62), and those reporting having first sex at 16 or under were more likely to report STI symptoms than those who delayed to 17–19 years (OR 1.27; 95% CI 1.003–1.62).

Conclusion

These findings highlight the need to improve the implementation of Adolescent Friendly Health Services available in Tanzania (especially in semi-rural areas). The inclusion of private facilities and pharmacies in AFHS scale-up would potentially raise the level of STI knowledge, lower the STI prevalence and reduce HIV incidence among youth.

Predictors of non-adherence to antiretroviral therapy among HIV infected patients in northern Tanzania

BACKGROUND

Antiretroviral therapy (ART) has been shown to reduce HIV-related morbidity and mortality amongst those living with HIV and reduce transmission of the virus to those who are yet to be infected. However, these outcomes depend on maximum ART adherence, and HIV programs around the world make efforts to ensure optimal adherence. Predictors of ART non-adherence vary considerably across populations and settings with respect to demographic, psychological, behavioral and economic factors. The objective of this study is to investigate risk factors that predict non-adherence to antiretroviral treatment among HIV-infected individuals in northern Tanzania.

METHODS

At Kilimanjaro Christian Medical Centre (KCMC), a tertiary and referral hospital in northern Tanzania, we used an existing ART database to randomly select HIV-infected patients above 18 years of age who have been on triple ART for at least two years. We used interviewer administered structured questionnaires to cross-sectionally determine predictors of ART non-adherence. We determined non-adherence through retrospective review of pharmacy drug refill (PDR) records of the interviewed participants using a pharmacy database.

RESULTS

Non-adherence was defined as collecting less than 95% of expected monthly refills in the previous 2 years. Multivariable logistic regression model was used to determine the predictors of non-adherence. Of the 256 patients enrolled mean age was 44 years (SD ± 11) and median CD4 count was 499 cells per microliter (IQR 332-690). Median PDR adherence was 71% (IQR 58%-75%). Non-adherence was associated with younger age and unemployment.

CONCLUSION

In this setting, adherence strategies could be adapted to address issues facing young adults, and those with household challenges such as unemployment. Further research is required to better understand the potential roles of these factors in suboptimal adherence.

Effects of schistosomiasis on susceptibility to HIV-1 infection and HIV-1 viral load at HIV-1 seroconversion: A nested case-control study

BACKGROUND

Schistosomiasis affects 218 million people worldwide, with most infections in Africa. Prevalence studies suggest that people with chronic schistosomiasis may have higher risk of HIV-1 acquisition and impaired ability to control HIV-1 replication once infected. We hypothesized that: (1) pre-existing schistosome infection may increase the odds of HIV-1 acquisition and that the effects may differ between men and women, and (2) individuals with active schistosome infection at the time of HIV-1 acquisition may have impaired immune control of HIV-1, resulting in higher HIV-1 viral loads at HIV-1 seroconversion.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a nested case-control study within a large population-based survey of HIV-1 transmission in Tanzania. A population of adults from seven villages was tested for HIV in 2007, 2010, and 2013 and dried blood spots were archived for future studies with participants' consent. Approximately 40% of this population has Schistosoma mansoni infection, and 2% has S. haematobium. We tested for schistosome antigens in the pre- and post-HIV-1-seroconversion blood spots of people who acquired HIV-1. We also tested blood spots of matched controls who did not acquire HIV-1 and calculated the odds that a person with schistosomiasis would become HIV-1-infected compared to these matched controls. Analysis was stratified by gender. We compared 73 HIV-1 seroconverters with 265 controls. Women with schistosome infections had a higher odds of HIV-1 acquisition than those without (adjusted OR = 2.8 [1.2-6.6], p = 0.019). Schistosome-infected men did not have an increased odds of HIV-1 acquisition (adjusted OR = 0.7 [0.3-1.8], p = 0.42). We additionally compared HIV-1 RNA levels in the post-seroconversion blood spots in HIV-1 seroconverters with schistosomiasis versus those without who became HIV-infected in 2010, before antiretroviral therapy was widely available in the region. The median whole blood HIV-1 RNA level in the 15 HIV-1 seroconverters with schistosome infection was significantly higher than in the 22 without schistosomiasis: 4.4 [3.9-4.6] log10 copies/mL versus 3.7 [3.2-4.3], p = 0.017.

CONCLUSIONS/SIGNIFICANCE

We confirm, in an area with endemic S. mansoni, that pre-existing schistosome infection increases odds of HIV-1 acquisition in women and raises HIV-1 viral load at the time of HIV-1 seroconversion. This is the first study to demonstrate the effect of schistosome infection on HIV-1 susceptibility and viral control, and to differentiate effects by gender. Validation studies will be needed at additional sites.

Household survey of HIV incidence in Rwanda: a national observational cohort study

BACKGROUND

In Rwanda, HIV prevalence among adults aged 15-49 years has been stable at 3% since 2005. The aim of this study was to characterise HIV incidence across Rwanda.

METHODS

We did a nationally representative, prospective HIV incidence survey for the period of 2013-14, which used two-stage sampling. We randomly selected 492 villages in the first sampling stage and 14 households per village in the second stage. Participants completed a questionnaire and 14 140 people were tested for HIV. 13 728 participants were HIV negative, and were enrolled in the incidence cohort. Participants were retested and surveyed again after 12 months. Weights were calculated as the inverse of the probability to select the villages and the households.

FINDINGS

The study period was from Nov 5, 2013, to Nov 15, 2014. Among 14 222 respondents from 6792 households, 14 140 were tested for HIV and 13 728 were HIV negative. Of 12 593 people who participated in the endpoint data collection activities, 5965 (47·4%) were men and the mean age was 30 years (SD 10·8). 11 237 (89·2%) participants lived in rural areas, 4826 (38·3%) were single, and 7140 (56·7%) were married or cohabitating. During the year, 35 participants had seroconversion, including 13 men and 22 women, resulting in an overall incidence of 0·27 per 100 person-years (95% CI 0·18-0·35). Incidence was 0·21 per 100 person-years (0·10-0·32) in men and 0·32 per 100 person-years (0·19-0·45) in women. Our findings suggested multiple breakouts, with multiple seroconversions occurring in three villages and two households. Incidence was higher in adults aged 36-45 years (0·37 per 100 person-years, 0·12-0·62; adjusted hazard ratio [aHR] 4·49, 95% CI 1·30-14·70) relative to those aged 16-25, higher in western province (0·57 per 100 person-years, 0·31-0·87; aHR 5·90, 1·33-25·28) relative to the northern province, and higher in urban areas (0·65 per 100 person-years, 0·23-1·07; aHR 3·10, 1·28-6·99) than in rural areas.

INTERPRETATION

The incidence of HIV in Rwanda was higher than that previously estimated from models, with outbreaks seeming to contribute to the ongoing epidemic. Characterisation of incident infections can help the national HIV programmes to plan for preventive interventions tailored to the most at risk populations.

FUNDING

Global Fund to Fight HIV, Tuberculosis and Malaria, WHO Rwanda, UNAIDS Rwanda, and the Government of Rwanda.

The population-level impact of public-sector antiretroviral therapy rollout on adult mortality in rural Malawi

BACKGROUND

Recent evidence from health and demographic surveillance sites (HDSS) has shown that increasing access to antiretroviral therapy (ART) is reducing mortality rates in sub-Saharan Africa (SSA). However, due to limited vital statistics registration in many of the countries most affected by the HIV/AIDS epidemic, there is limited evidence of the magnitude of ART’s effect outside of specific HDSS sites. This paper leverages longitudinal household/family roster data from the Malawi Longitudinal Survey of Families and Health (MLSFH) to estimate the effect of ART availability in public clinics on population-level mortality based on a geographically dispersed sample of individuals in rural Malawi.

OBJECTIVE

We seek to provide evidence on the population-level magnitude of the ART-associated mortality decline in rural Malawi and confirm that this population is experiencing similar declines in mortality as those seen in HDSS sites.

METHODS

We analyze longitudinal household/family-roster data from four waves of the MLSFH to estimate mortality change after the introduction of ART to study areas. We analyze life expectancy using the Kaplan–Meier estimator and examine how the mortality hazard changed over time by individual characteristics with Cox regression.

RESULTS

In the four years following rollout of ART, life expectancy at age 15 increased by 3.1 years (95% CI 1.1, 5.1), and median length of life rose by over ten years.

CONTRIBUTION

Our observations show that the increased availability of ART resulted in a substantial and sustained reversal of mortality trends in SSA and assuage concerns that the post-ART reversals in mortality are not occurring at the same magnitude outside of specific HDSSs.

"I don't have options but to persevere." Experiences and practices of care for HIV and diabetes in rural Tanzania: a qualitative study of patients and family caregivers

Background

The high prevalence of chronic diseases in Tanzania is putting a strain on the already stretched health care services, patients and their families. This study sought to find out how health care for diabetes and HIV is perceived, practiced and experienced by patients and family caregivers, to inform strategies to improve continuity of care.

Methods

Thirty two in-depth interviews were conducted among 19 patients (10 HIV, 9 diabetes) and 13 family caregivers (6 HIV, 7 diabetes). Diabetes patients and caregivers were accessed through one referral facility. HIV patients and caregivers were accessed through HIV clinics at the district hospital, one health centre and one dispensary respectively. The innovative care for chronic conditions framework informed the study design. Data was analysed with the help of Nvivo 10.

Results

Three major themes emerged; preparedness and practices in care, health care at health facilities and community support in care for HIV and diabetes. In preparedness and practices, HIV patients and caregivers knew more about aspects of HIV than did diabetes patients and caregivers on diabetes aspects. Continued education on care for the conditions was better structured for HIV than diabetes. On care at facilities, HIV and diabetes patients reported that they appreciated familiarity with providers, warm reception, gentle correction of mistakes and privacy during care. HIV services were free of charge at all levels. Costs involved in seeking services resulted in some diabetes patients to not keep appointments. There was limited community support for care of diabetes patients. Community support for HIV care was through community health workers, patient groups, and village leaders.

Conclusion

Diabetes and HIV have socio-cultural and economic implications for patients and their families. The HIV programme is successfully using decentralization of health services, task shifting and CHWs to address these implications. For diabetes and NCDs, decentralization and task shifting are also important and, strengthening of community involvement is warranted for continuity of care and patient centeredness in care. While considering differences between HIV and diabetes, we have shown that Tanzania’s rich experiences in community involvement in health can be leveraged for care and treatment of diabetes and other NCDs.

Migration, sexual behaviour, and HIV risk: a general population cohort in rural South Africa

BACKGROUND

Increased sexual risk behaviour and HIV prevalence have been reported in migrants compared with nonmigrants in sub-Saharan Africa. We investigated the association of residential and migration patterns with sexual HIV risk behaviours and HIV prevalence in an open, general population cohort in rural KwaZulu-Natal, South Africa.

METHODS

In a mainly rural demographic surveillance area in northern KwaZulu-Natal, South Africa, we collected longitudinal demographic, migration, sexual behaviour, and HIV status data through household surveillance twice per year and individual surveillance once per year. All resident household members and a sample of non-resident household members (stratified by sex and migration patterns) were eligible for participation. Participants reported sexual risk behaviours, including data for multiple, concurrent, and casual sexual partners and condom use, and gave a dried blood spot sample via fingerprick for HIV testing. We investigated population-level differences in sexual HIV risk behaviours and HIV prevalence with respect to migration indicators using logistic regression models.

FINDINGS

Between Jan 1, 2005, and Dec 31, 2011, the total eligible population at each surveillance round ranged between 21 129 and 22 726 women (aged 17-49 years) and between 20 399 and 22 100 men (aged 17-54 years). The number of eligible residents in any round ranged from 24 395 to 26 664 and the number of eligible non-residents ranged from 17 002 to 18 891 between rounds. The stratified sample of non-residents included between 2350 and 3366 individuals each year. Sexual risk behaviours were significantly more common in non-residents than in residents for both men and women. Estimated differences in sexual risk behaviours, but not HIV prevalence, varied between the migration indicators: recent migration, mobility, and migration type. HIV prevalence was significantly increased in current residents with a recent history of migration compared with other residents in the study area in men(adjusted odds ratio 1·19, 95% CI 1·07-1·33) and in women (1·18, 1·10-1·26).

INTERPRETATION

Local information about migrants and highly mobile individuals could help to target intervention strategies that are based on the identification of transmission hotspots.Funding Wellcome Trust.

Embracing different approaches to estimating HIV incidence, prevalence and mortality

Background:

Joint United Nations Programme on HIV/AIDS (UNAIDS) and Murray et al. have both produced sets of estimates for worldwide HIV incidence, prevalence and mortality. Understanding differences in these estimates can strengthen the interpretation of each.

Methods:

We describe differences in the two sets of estimates. Where possible, we have drawn on additional published data to which estimates can be compared.

Findings:

UNAIDS estimates that there were 6 million more people living with HIV (PLHIV) in 2013 (35 million) compared with the Murray et al. estimates (29 million). Murray et al. estimate that new infections and AIDS deaths have declined more gradually than does UNAIDS. Just under one third of the difference in PLHIV is in Africa, where Murray et al. have relied more on estimates of adult mortality trends than on data on survival times. Another third of the difference is in North America, Europe, Central Asia and Australasia. Here Murray et al. estimates of new infections are substantially lower than the number of new HIV/AIDS diagnoses reported by countries, whereas published UNAIDS estimate tend to be greater. The remaining differences are in Latin America and Asia where the data upon which the UNAIDS methods currently rely are more sparse, whereas the mortality data leveraged by Murray et al. may be stronger. In this region, however, anomalies appear to exist between the both sets of estimates and other data.

Interpretation:

Both estimates indicate that approximately 30 million PLHIV and that antiretroviral therapy has driven large reductions in mortality. Both estimates are useful but show instructive discrepancies with additional data sources. We find little evidence to suggest that either set of estimates can be considered systematically more accurate. Further work should seek to build estimates on as wide a base of data as possible.

The impact of voluntary counselling and testing services on sexual behaviour change and HIV incidence: observations from a cohort study in rural Tanzania

Background

It is widely assumed that voluntary counselling and testing (VCT) services contribute to HIV prevention by motivating clients to reduce sexual risk-taking. However, findings from sub-Saharan Africa have been mixed, particularly among HIV-negative persons. We explored associations between VCT use and changes in sexual risk behaviours and HIV incidence using data from a community HIV cohort study in northwest Tanzania.

Methods

Data on VCT use, sexual behaviour and HIV status were available from three HIV serological surveillance rounds undertaken in 2003–4 (Sero4), 2006–7 (Sero5) and 2010 (Sero6). We used multinomial logistic regression to assess changes in sexual risk behaviours between rounds, and Poisson regression to estimate HIV incidence.

Results

The analyses included 3,613 participants attending Sero4 and Sero5 (3,474 HIV-negative and 139 HIV-positive at earlier round) and 2,998 attending Sero5 and Sero6 (2,858 HIV-negative and 140 HIV-positive at earlier round). Among HIV-negative individuals VCT use was associated with reductions in the number of sexual partners in the last year (aRR Seros 4–5: 1.42, 95% CI 1.07-1.88; aRR Seros 5–6: 1.68, 95% CI 1.25-2.26) and in the likelihood of having a non-cohabiting partner in the last year (aRR Seros 4–5: 1.57, 95% CI 1.10-2.25; aRR Seros 5–6: 1.48, 95% CI 1.07-2.04) or a high-risk partner in the last year (aRR Seros 5–6 1.57, 95% CI 1.06-2.31). However, VCT was also associated with stopping using condoms with non-cohabiting partners between Seros 4–5 (aRR 4.88, 95% CI 1.39-17.16). There were no statistically significant associations between VCT use and changes in HIV incidence, nor changes in sexual behaviour among HIV-positive individuals, possibly due to small sample sizes.

Conclusions

We found moderate associations between VCT use and reductions in some sexual risk behaviours among HIV-negative participants, but no impacts among HIV-positive individuals in the context of low overall VCT uptake. Furthermore, there were no significant changes in HIV incidence associated with VCT use, although declining background incidence and small sample sizes may have prevented us from detecting this. The impact of VCT services will ultimately depend upon rates of uptake, with further research required to better understand processes of behaviour change following VCT use.

Adjusting the HIV prevalence for non-respondents using mortality rates in an open cohort in northwest Tanzania

Objective

To estimate HIV prevalence in adults who have not tested for HIV using age‐specific mortality rates and to adjust the overall population HIV prevalence to include both tested and untested adults.

Methods

An open cohort study was established since 1994 with demographic surveillance system (DSS) and five serological surveys conducted. Deaths from Kisesa DSS were used to estimate mortality rates and 95% confidence intervals by HIV status for 3‐ 5‐year periods (1995–1999, 2000–2004, and 2005–2009). Assuming that mortality rates in individuals who did not test for HIV are similar to those in tested individuals, and dependent on age, sex and HIV status and HIV, prevalence was estimated.

Results

In 1995–1999, mortality rates (per 1000 person years) were 43.7 (95% CI 35.7–53.4) for HIV positive, 2.6 (95% CI 2.1–3.2) in HIV negative and 16.4 (95% CI 14.4–18.7) in untested. In 2000–2004, mortality rates were 43.3 (95% CI 36.2–51.9) in HIV positive, 3.3 (95% CI 2.8–4.0) in HIV negative and 11.9 (95% CI 10.5–13.6) in untested. In 2005–2009, mortality rates were 30.7 (95% CI 24.8–38.0) in HIV positive, 4.1 (95% CI 3.5–4.9) in HIV negative and 5.7 (95% CI 5.0–6.6) in untested residents. In the three survey periods (1995–1999, 2000–2004, 2005–2009), the adjusted period prevalences of HIV, including the untested, were 13.5%, 11.6% and 7.1%, compared with the observed prevalence in the tested of 6.0%, 6.8 and 8.0%. The estimated prevalence in the untested was 33.4%, 21.6% and 6.1% in the three survey periods.

Conclusion

The simple model was able to estimate HIV prevalence where a DSS provided mortality data for untested residents.

Using HIV-attributable mortality to assess the impact of antiretroviral therapy on adult mortality in rural Tanzania

Background

The Tanzanian national HIV care and treatment programme has provided free antiretroviral therapy (ART) to HIV-positive persons since 2004. ART has been available to participants of the Kisesa open cohort study since 2005, but data to 2007 showed a slow uptake of ART and a modest impact on mortality. Additional data from the 2010 HIV serological survey provide an opportunity to update the estimated impact of ART in this setting.

Methods

The Kisesa Health and Demographic Surveillance Site (HDSS) has collected HIV serological data and demographic data, including verbal autopsy (VA) interviews since 1994. Serological data to the end of 2010 were used to make two estimates of HIV-attributable mortality, the first among HIV positives using the difference in mortality between HIV positives and HIV negatives, and the second in the population using the difference between the observed mortality rate in the whole population and the mortality rate among the HIV negatives. Four time periods (1994–1999, 2000–2004, 2005–2007, and 2008–2010) were used and HIV-attributable mortality estimates were analysed in detail for trends over time. A computer algorithm, InterVA-4, was applied to VA data to estimate the HIV-attributable mortality for the population, and this was compared to the estimates from the serological survey data.

Results

Among HIV-positive adults aged 45–59 years, high mortality rates were observed across all time periods in both males and females. In HIV-positive men, the HIV-attributable mortality was 91.6% (95% confidence interval (CI): 84.6%–95.3%) in 2000–2004 and 86.3% (95% CI: 71.1%–93.3%) in 2008–2010, while among women, the HIV-attributable mortality was 87.8% (95% CI: 71.1%–94.3%) in 2000–2004 and 85.8% (95% CI: 59.6%–94.4%) in 2008–2010. In the whole population, using the serological data, the HIV-attributable mortality among men aged 30–44 years decreased from 57.2% (95% CI: 46.9%–65.3%) in 2000–2004 to 36.5% (95% CI: 18.8%–50.1%) in 2008–2010, while among women the corresponding decrease was from 57.3% (95% CI: 49.7%–63.6%) to 38.7% (95% CI: 27.4%–48.2%). The HIV-attributable mortality in the population using estimates from the InterVA model was lower than that from HIV sero-status data in the period prior to ART, but slightly higher once ART became available.

Discussion

In the Kisesa HDSS, ART availability corresponds with a decline in adult overall mortality, although not as large as expected. Using InterVA to estimate HIV-attributable mortality showed smaller changes in HIV-related mortality following ART availability than the serological results.

Using vignettes in qualitative research to explore barriers and facilitating factors to the uptake of prevention of mother-to-child transmission services in rural Tanzania: a critical analysis

Background

Vignettes are short stories about a hypothetical person, traditionally used within research (quantitative or qualitative) on sensitive topics in the developed world. Studies using vignettes in the developing world are emerging, but with no critical examination of their usefulness in such settings. We describe the development and application of vignettes to a qualitative investigation of barriers to uptake of prevention of mother-to-child transmission (PMTCT) HIV services in rural Tanzania in 2012, and critique the successes and challenges of using the technique in this setting.

Methods

Participatory Learning and Action (PLA) group activities (3 male; 3 female groups from Kisesa, north-west Tanzania) were used to develop a vignette representing realistic experiences of an HIV-infected pregnant woman in the community. The vignette was discussed during in-depth interviews with 16 HIV-positive women, 3 partners/relatives, and 5 HIV-negative women who had given birth recently. A critical analysis was applied to assess the development, implementation and usefulness of the vignette.

Results

The majority of in-depth interviewees understood the concept of the vignette and felt the story was realistic, although the story or questions needed repeating in some cases. In-depth interviewers generally applied the vignette as intended, though occasionally were unsure whether to steer the conversation back to the vignette character when participants segued into personal experiences. Interviewees were occasionally confused by questions and responded with what the character should do rather than would do; also confusing fieldworkers and presenting difficulties for researchers in interpretation. Use of the vignette achieved the main objectives, putting most participants at ease and generating data on barriers to PMTCT service uptake. Participants’ responses to the vignette often reflected their own experience (revealed later in the interviews).

Conclusions

Participatory group research is an effective method for developing vignettes. A vignette was incorporated into qualitative interview discussion guides and used successfully in rural Africa to draw out barriers to PMTCT service use; vignettes may also be valuable in HIV, health service use and drug adherence research in this setting. Application of this technique can prove challenging for fieldworkers, so thorough training should be provided prior to its use.

Does the Spectrum model accurately predict trends in adult mortality? Evaluation of model estimates using empirical data from a rural HIV community cohort study in North-Western Tanzania

Introduction

Spectrum epidemiological models are used by UNAIDS to provide global, regional and national HIV estimates and projections, which are then used for evidence-based health planning for HIV services. However, there are no validations of the Spectrum model against empirical serological and mortality data from populations in sub-Saharan Africa.

Methods

Serologic, demographic and verbal autopsy data have been regularly collected among over 30,000 residents in north-western Tanzania since 1994. Five-year age-specific mortality rates (ASMRs) per 1,000 person years and the probability of dying between 15 and 60 years of age (₄₅Q₁₅,) were calculated and compared with the Spectrum model outputs. Mortality trends by HIV status are shown for periods before the introduction of antiretroviral therapy (1994–1999, 2000–2005) and the first 5 years afterwards (2005–2009).

Results

Among 30–34 year olds of both sexes, observed ASMRs per 1,000 person years were 13.33 (95% CI: 10.75–16.52) in the period 1994–1999, 11.03 (95% CI: 8.84–13.77) in 2000–2004, and 6.22 (95% CI; 4.75–8.15) in 2005–2009. Among the same age group, the ASMRs estimated by the Spectrum model were 10.55, 11.13 and 8.15 for the periods 1994–1999, 2000–2004 and 2005–2009, respectively. The cohort data, for both sexes combined, showed that the ₄₅Q₁₅ declined from 39% (95% CI: 27–55%) in 1994 to 22% (95% CI: 17–29%) in 2009, whereas the Spectrum model predicted a decline from 43% in 1994 to 37% in 2009.

Conclusion

From 1994 to 2009, the observed decrease in ASMRs was steeper in younger age groups than that predicted by the Spectrum model, perhaps because the Spectrum model under-estimated the ASMRs in 30–34 year olds in 1994–99. However, the Spectrum model predicted a greater decrease in ₄₅Q₁₅ mortality than observed in the cohort, although the reasons for this over-estimate are unclear.

Is the risk of HIV acquisition increased during and immediately after pregnancy? A secondary analysis of pooled HIV community-based studies from the ALPHA network

BACKGROUND

Previous studies of HIV acquisition in pregnancy have been in specific population groups, such as sero-discordant couples which have shown an increased risk of HIV acquisition during pregnancy and studies of sexually active women where the results have been ambiguous. However these studies are unable to tell us what the overall impact of pregnancy is on HIV acquisition in the general population.

METHODS

Data from six community-based HIV cohorts were pooled to give 2,628 sero-conversions and a total of 178,000 person years of observation. Multiple imputation was used to allow for the uncertainty of exact sero-conversion date in surveillance intervals greater than the length of a pregnancy. Results were combined using Rubin's rules to give appropriate error bounds. The analysis was stratified into two periods: pre- and post- widespread availability of prevention of mother-to-child HIV transmission services. This allows us to assess whether there is reporting bias relating to a person's knowledge of their own HIV status which would become more widespread in the latter time period.

RESULTS

Results suggest that women while pregnant have a lower risk of acquiring HIV infection over all periods (HRR 0.79, 95%CI 0.70-0.89) than women who were not pregnant. There is no evidence for a difference in the rate of HIV acquisition between postpartum and non-pregnant women (HRR 0.92 95%CI 0.84-1.03).

DISCUSSION

Although there may be immunological reasons for increased risk of HIV acquisition during pregnancy, at a population level this study indicates a lower risk of HIV acquisition for pregnant women. Pregnant women may be more likely to be concordant with their current sexual partner than non-pregnant women, i.e. either already HIV positive prior to the pregnancy or if negative at the time of becoming pregnant more likely to have a negative partner.

Deciphering the complex distribution of human immunodeficiency virus type 1 subtypes among different cohorts in Northern Tanzania

Background

Increased understanding of the genetic diversity of HIV-1 is challenging but important in the development of an effective vaccine. We aimed to describe the distribution of HIV-1 subtypes in northern Tanzania among women enrolled in studies preparing for HIV-1 prevention trials (hospitality facility-worker cohorts), and among men and women in an open cohort demographic surveillance system (Kisesa cohort).

Methods

The polymerase encompassing partial reverse transcriptase was sequenced and phylogenetic analysis performed and subtype determined. Questionnaires documented demographic data. We examined factors associated with subtype using multinomial logistic regression, adjusted for study, age, and sex.

Results

Among 140 individuals (125 women and 15 men), subtype A1 predominated (54, 39%), followed by C (46, 33%), D (25, 18%) and unique recombinant forms (URFs) (15, 11%). There was weak evidence to suggest different subtype frequencies by study (for example, 18% URFs in the Kisesa cohort versus 5–9% in the hospitality facility-worker cohorts; adjusted relative-risk ratio (aRR) = 2.35 [95% CI 0.59,9.32]; global p = 0.09). Compared to men, women were less likely to have subtype D versus A (aRR = 0.12 [95% CI 0.02,0.76]; global p = 0.05). There was a trend to suggest lower relative risk of subtype D compared to A with older age (aRR = 0.44 [95% CI 0.23,0.85] per 10 years; global p = 0.05).

Conclusions

We observed multiple subtypes, confirming the complex genetic diversity of HIV-1 strains circulating in northern Tanzania, and found some differences between cohorts and by age and sex. This has important implications for vaccine design and development, providing opportunity to determine vaccine efficacy in diverse HIV-1 strains.

The trade-off between accuracy and accessibility of syphilis screening assays

The availability of rapid and sensitive methods to diagnose syphilis facilitates screening of pregnant women, which is one of the most cost-effective health interventions available. We have evaluated two screening methods in Tanzania: an enzyme immunoassay (EIA), and a point-of-care test (POCT). We evaluated the performance of each test against the Treponema pallidum particle agglutination assay (TPPA) as the reference method, and the accessibility of testing in a rural district of Tanzania. The POCT was performed in the clinic on whole blood, while the other assays were performed on plasma in the laboratory. Samples were also tested by the rapid plasma Reagin (RPR) test. With TPPA as reference assay, the sensitivity and specificity of EIA were 95.3% and 97.8%, and of the POCT were 59.6% and 99.4% respectively. The sensitivity of the POCT and EIA for active syphilis cases (TPPA positive and RPR titer ≥ 1/8) were 82% and 100% respectively. Only 15% of antenatal clinic attenders in this district visited a health facility with a laboratory capable of performing the EIA. Although it is less sensitive than EIA, its greater accessibility, and the fact that treatment can be given on the same day, means that the use of POCT would result in a higher proportion of women with syphilis receiving treatment than with the EIA in this district of Tanzania.

Do accurate HIV and antiretroviral therapy knowledge, and previous testing experiences increase the uptake of HIV voluntary counselling and testing? Results from a cohort study in rural Tanzania

BACKGROUND

Despite the introduction of free antiretroviral therapy (ART), the use of voluntary counselling and testing (VCT) services remains persistently low in many African countries. This study investigates how prior experience of HIV and VCT, and knowledge about HIV and ART influence VCT use in rural Tanzania.

METHODS

In 2006-7, VCT was offered to study participants during the fifth survey round of an HIV community cohort study that includes HIV testing for research purposes without results disclosure, and a questionnaire covering knowledge, attitudes and practices around HIV infection and HIV services. Categorical variables were created for HIV knowledge and ART knowledge, with "good" HIV and ART knowledge defined as correctly answering at least 4/6 and 5/7 questions about HIV and ART respectively. Experience of HIV was defined as knowing people living with HIV, or having died from AIDS. Logistic regression methods were used to assess how HIV and ART knowledge, and prior experiences of HIV and VCT were associated with VCT uptake, with adjustment for HIV status and socio-demographic confounders.

RESULTS

2,695/3,886 (69%) men and 2,708/5,575 women (49%) had "good" HIV knowledge, while 613/3,886 (16%) men and 585/5575 (10%) women had "good" ART knowledge. Misconceptions about HIV transmission were common, including through kissing (55% of women, 43% of men), or mosquito bites (42% of women, 34% of men).19% of men and 16% of women used VCT during the survey. After controlling for HIV status and socio-demographic factors, the odds of VCT use were lower among those with poor HIV knowledge (aOR = 0.5; p = 0.01 for men and aOR = 0.6; p < 0.01 for women) and poor ART knowledge (aOR = 0.8; p = 0.06 for men, aOR = 0.8; p < 0.01 for women), and higher among those with HIV experience (aOR = 1.3 for men and aOR = 1.6 for women, p < 0.01) and positive prior VCT experience (aOR = 2.0 for all men and aOR = 2.0 for HIV-negative women only, p < 0.001).

CONCLUSIONS

Two years after the introduction of free ART in this setting, misconceptions regarding HIV transmission remain rife and knowledge regarding treatment is worryingly poor, especially among women and HIV-positive people. Further HIV-related information, education and communication activities are urgently needed to improve VCT uptake in rural Tanzania.

HIV incidence from the first population-based cohort study in India

Background

Understanding about who acquires new HIV infection and the determinants of why some persons get infected and others do not is fundamental to controlling HIV in the population. We assess HIV incidence and its associations in the population of a high HIV burden district in Andhra Pradesh state in southern India by a population-based longitudinal cohort study.

Methods

We re-surveyed a population-based cohort of 12,617 adults in Guntur district of Andhra Pradesh for which we had reported a baseline HIV prevalence of 1.72% (rural 1.64%, urban 1.89%) among the 15–49 years age group in 2004–2005. We conducted interviews to assess risk behaviour and performed HIV testing again in 2010–2011. We assessed the rate of new HIV infection and its associations using multiple logistic regression.

Results

The participation rate in the follow-up was 74.9% and 63.9% of the baseline rural and urban samples, respectively. Over a mean follow-up of 5.63 years, the incidence of HIV was 1.26 per 1000 person-years (95% CI 0.83-1.69), after adjusting for slight compositional bias in the follow-up sample. The incidence per 1000 person-years was higher among rural men (1.68) than urban men (0.85), and among rural women (1.28) than urban women (0.54). The strongest association with incidence was a HIV positive spouse in the baseline for both men (odds ratio 266, 95% CI 62–1137) and women (odds ratio 28, 95% CI 9–88). Among men the other significant associations with HIV incidence were frequent use of condom for sex over the past 6 months, non-circumcision, more than one lifetime woman sex partner or ever visited sex worker, and transport-related occupation; for women the other significant associations were having had HIV testing other than antenatal check-up, previously married but currently not, and tobacco use.

Conclusion

These first population-based cohort incidence data from India suggest that rural areas of high HIV burden states would need more attention to prevent new HIV infections, and that spouses of HIV positive persons and some other risk groups need to be targeted more effectively by HIV prevention programmes.

Estimates of age-specific reductions in HIV prevalence in Uganda: Bayesian melding estimation and probabilistic population forecast with an HIV-enabled cohort component projection model

BACKGROUND

Much of our knowledge of the epidemiology and demography of HIV epidemics in Africa is derived from models fit to sparse, non-representative data. These often average over age and other important dimensions, rarely quantify uncertainty, and typically do not impose consistency on the epidemiology and the demography of the population.

OBJECTIVE

This work conducts an empirical investigation of the history of the HIV epidemic in Uganda and Tanzania through the late 1990s, focusing on sex-age-specific incidence, uses those results to produce probabilistic forecasts of HIV prevalence ten years later, and compares those to measures of HIV prevalence at the later time to describe the sex-age pattern of changes in prevalence over the intervening period.

METHODS

We adapt an epidemographic model of a population affected by HIV so that its parameters can be estimated using both the Bayesian melding with IMIS estimation method and maximum likelihood methods. Using the Bayesian version of the model we produce probabilistic forecasts of the population with HIV.

RESULTS

We produce estimates of sex-age-specific HIV incidence in Uganda and Tanzania in the late 1990s, produce probabilistic forecasts of the HIV epidemics in Uganda and Tanzania during the early 2000s, describe the sex-age pattern of changes in HIV prevalence in Uganda during the early 2000s, and compare the performance and results of the Bayesian and maximum likelihood estimation procedures.

CONCLUSIONS

We demonstrate that: (1) it is possible to model HIV epidemics in Africa taking account of sex and age, (2) there are important advantages to the Bayesian estimation method, including rigorous quantification of uncertainty and the ability to make probabilistic forecasts, and (3) that there were important age-specific changes in HIV incidence in Uganda during the early 2000s.

HIV status and participation in HIV surveillance in the era of antiretroviral treatment: a study of linked population-based and clinical data in rural South Africa

OBJECTIVE

To examine whether HIV status affects participation in a population-based longitudinal HIV surveillance in the context of an expanding HIV treatment and care programme in rural South Africa.

METHOD

We regressed consent to participate in the HIV surveillance during the most recent fieldworker visit on HIV status (based on previous surveillance participation or enrollment in pre-antiretroviral treatment (pre-ART) care or ART in the local HIV treatment and care programme), controlling for sex, age and year of the visit (N = 25,940). We then repeated the regression using the same sample but, in one model, stratifying HIV-infected persons into three groups (neither enrolled in pre-ART care nor receiving ART; enrolled in pre-ART care but not receiving ART; receiving ART) and, in another model, additionally stratifying the group enrolled in pre-ART and the group receiving ART into those with CD4 count ≤ 200/μl (i.e. the ART eligibility threshold at the time) vs. those with CD4 count >200/μl.

RESULTS

HIV-infected individuals were significantly less likely to consent to participate in the surveillance than HIV-uninfected individuals [adjusted odds ratio (aOR), 0.74; 95% confidence interval, 0.70-0.79, P < 0.001], controlling for other factors. Persons who were receiving ART were less likely to consent to participate (aOR, 0.75, 0.68-0.84, P < 0.001) than those who had never sought HIV treatment or care (aOR, 0.82, 0.75-0.89, P < 0.001), but more likely to consent than persons enrolled in pre-ART care (aOR 0.62, 0.56-0.69, P < 0.001). Those with CD4 count ≤ 200/μl were significantly less likely to consent to participate than those with CD4 count >200/μl in both the group enrolled in pre-ART and the group receiving ART.

CONCLUSION

As HIV test results are not made available to participants in the HIV surveillance, our findings agree with the hypothesis that HIV-infected persons are less likely than HIV-uninfected persons to participate in HIV surveillance because they fear the negative consequences of others learning about their HIV infection. Our results further suggest that the increased knowledge of HIV status that accompanies improved ART access can reduce surveillance participation of HIV-infected persons, but that this effect decreases after ART initiation, in particular in successfully treated patients.

Trends in the uptake of voluntary counselling and testing for HIV in rural Tanzania in the context of the scale up of antiretroviral therapy

OBJECTIVES

To describe trends in voluntary counselling and testing (VCT) use and to assess whether high-risk and infected individuals are receiving counselling and learning their HIV status in rural Tanzania.

METHODS

During two rounds of linked serological surveys (2003-2004 and 2006-2007) with anonymous HIV testing among adults, VCT was offered to all participants. The crude and adjusted odds ratios for completing VCT in each survey were calculated to compare uptake by demographic, behavioural and clinical characteristics, stratified by sex. Repeat testing patterns were also investigated.

RESULTS

The proportion of participants completing VCT increased from 10% in 2003-2004 to 17% in 2006-2007, and among HIV-infected persons from 14% to 25%. A higher proportion of men than women completed VCT in both rounds, but the difference declined over time. Socio-demographic and behavioural factors associated with VCT completion were similar across rounds, including higher adjusted odds of VCT with increasing numbers of sexual partners in the past 12 months. The proportion having ever-completed VCT reached 26% among 2006-2007 attendees, with repeat testing rates highest among those aged 35-44 years. Among 3923 participants attending both rounds, VCT completion in 2006-2007 was 17% among 3702 who were HIV negative in both rounds, 19% among 124 who were HIV infected in both rounds and 22% among 96 who seroconverted between rounds.

CONCLUSION

VCT services are attracting HIV-infected and high-risk individuals. However, 2 years after the introduction of antiretroviral therapy, the overall uptake remains low. Intensive mobilisation efforts are needed to achieve regular and universal VCT use.

Using age-specific mortality of HIV infected persons to predict anti-retroviral treatment need: a comparative analysis of data from five African population-based cohort studies

OBJECTIVES

To present a simple method for estimating population-level anti-retroviral therapy (ART) need that does not rely on knowledge of past HIV incidence.

METHODS

A new approach to estimating ART need is developed based on calculating age-specific proportions of HIV-infected adults expected to die within a fixed number of years in the absence of treatment. Mortality data for HIV-infected adults in the pre-treatment era from five African HIV cohort studies were combined to construct a life table, starting at age 15, smoothed with a Weibull model. Assuming that ART should be made available to anyone expected to die within 3 years, conditional 3-year survival probabilities were computed to represent proportions needing ART. The build-up of ART need in a successful programme continuously recruiting infected adults into treatment as they age to within 3 years of expected death was represented by annually extending the conditional survival range.

RESULTS

The Weibull model: survival probability in the infected state from age 15 = exp(-0.0073 × (age - 15)(1.69)) fitted the pooled age-specific mortality data very closely. Initial treatment need for infected persons increased rapidly with age, from 15% at age 20-24 to 32% at age 40-44 and 42% at age 60-64. Overall need in the treatment of naïve population was 24%, doubling within 5 years in a programme continually recruiting patients entering the high-risk period for dying.

CONCLUSION

A reasonable projection of treatment need in an ART naive population can be made based on the age and gender profile of HIV-infected people.

Association of Schistosomiasis and HIV infection in Tanzania

Animal and human studies suggest that Schistosoma mansoni infection may increase risk of human immunodeficiency virus (HIV) acquisition. Therefore, we tested 345 reproductive age women in rural Tanzanian villages near Lake Victoria, where S. mansoni is hyperendemic, for sexually transmitted infections (STIs) and schistosomiasis by circulating anodic antigen (CAA) serum assay. Over one-half (54%) had an active schistosome infection; 6% were HIV-seropositive. By univariate analysis, only schistosome infection predicted HIV infection (odds ratio [OR] = 3.9, 95% confidence interval = [1.3-12.0], P = 0.015) and remained significant using multivariate analysis to control for age, STIs, and distance from the lake (OR = 6.2 [1.7-22.9], P = 0.006). HIV prevalence was higher among women with more intense schistosome infections (P = 0.005), and the median schistosome intensity was higher in HIV-infected than -uninfected women (400 versus 15 pg CAA/mL, P = 0.01). This finding suggests that S. mansoni infection may be a modifiable HIV risk factor that places millions of people worldwide at increased risk of HIV acquisition.

The impact of antiretroviral therapy on adult mortality in rural Tanzania

OBJECTIVE

To describe the impact of antiretroviral therapy (ART) on mortality rates among adults participating in an HIV community cohort study in north-west Tanzania.

METHODS

Serological and demographic surveillance rounds have been undertaken in a population of approximately 30,000 people since 1994. Free HIV care including ART has been available since 2005. Event history analysis was used to compare mortality rates among HIV-negative and HIV-positive adults in the 5-year period before and after the introduction of ART. Crude and adjusted hazard ratios were calculated using exponential regression models. Interaction between time period and HIV status was assessed to investigate whether there was a non-linear relationship between these two variables.

RESULTS

Male and female mortality patterns varied over the pre- and post-ART period. In women, the crude death rate fell for both HIV negatives and HIV positives hazard rate ratio (HRR = 0.71; 95%CI 0.51-0.99 and HRR = 0.68; 95%CI: 0.46-0.99, respectively). For men, the mortality among the HIV negatives increased (HRR = 1.47; 95%CI: 1.06-2.03) while the decline in mortality among the HIV positives (HRR = 0.77; 95%CI 0.52-1.13) was not statistically significant. The largest decrease in HIV-positive mortality over the two periods was among the 30- to 44-year-old age group for women and among the 45- to 59-year-old age group for men.

CONCLUSION

There has been a modest effect on mortality in the study population following the introduction of free ART 5 years ago. Improving access to treatment and placing greater focus on retaining individuals on treatment are essential if the full potential of treatment for reducing HIV-related mortality is to be realised.

Rapid increase in prevalence of male circumcision in rural Tanzania in the absence of a promotional campaign

Objectives

To estimate the prevalence of circumcision among young men in rural Mwanza, North-Western Tanzania, and document trends in circumcision prevalence over time. To investigate associations of circumcision with socio-demographic characteristics, reported sexual behaviours and sexually transmitted infections (STIs).

Design

A cross-sectional survey in communities which had previously participated in a cluster-randomized trial of an adolescent sexual health intervention that did not include male circumcision in 20 rural communities.

Methods

In 2007/08, 7300 young men (age 16–23 years) were interviewed and examined by a clinician. The prevalence of circumcision by age was compared with data collected during the trial in 1998–2002. Odds ratios (OR) and 95% confidence intervals (CI) for the association of circumcision with socio-demographic characteristics, reported sexual behaviours and with HIV and other STIs were estimated using multivariable conditional logistic regression.

Results

The prevalence of male circumcision was 40.6%, and age-specific prevalence had more than doubled since 2001/2002. Circumcised men reported less risky sexual behaviours, being more likely to report having ever used a condom (adjusted OR = 2.62, 95%CI:2.32–2.95). Men circumcised before sexual debut were at reduced risk of being HIV seropositive compared with non-circumcised men (adjusted OR = 0.50, 95%CI:0.25–0.97), and also had reduced risks of HSV-2 infection and genital ulcer syndrome in the past 12 months compared with non-circumcised men.

Conclusions

There was a steep increase in circumcision prevalence between 2001/02 and 2007/08 in the absence of a promotional campaign. Circumcised men reported safer sexual practices than non-circumcised men and had lower prevalence of HIV and HSV-2 infection.

Evaluation of knowledge levels amongst village AIDS committees after undergoing HIV educational sessions: results from a pilot study in rural Tanzania

Background

Village AIDS committees (VAC) were formed by the Tanzanian government in 2003 to provide HIV education to their communities. However, their potential has not been realised due to their limited knowledge and misconceptions surrounding HIV, which could be addressed through training of VAC members. In an attempt to increase HIV knowledge levels and address common misconceptions amongst the VACs, an HIV curriculum was delivered to members in rural north western Tanzania.

Methods

An evaluation of HIV knowledge was conducted prior to and post-delivery of HIV training sessions, within members of three VACs in Kisesa ward. Quantitative surveys were used with several open-ended questions to identify local misconceptions and evaluate HIV knowledge levels. Short educational training sessions covering HIV transmission, prevention and treatment were conducted, with each VAC using quizzes, role-plays and participatory learning and action tools. Post-training surveys occurred up to seven days after the final training session.

Results

Before the training, "good" HIV knowledge was higher amongst men than women (p = 0.041), and among those with previous HIV education (p = 0.002). The trade-centre had a faster turn-over of VAC members, and proximity to the trade-centre was associated with a shorter time on the committee.

Training improved HIV knowledge levels with more members achieving a "good" score in the post-training survey compared with the baseline survey (p = < 0.001). The training programme was popular, with 100% of participants requesting further HIV training in the future and 51.7% requesting training at three-monthly intervals.

Conclusions

In this setting, a series of HIV training sessions for VACs demonstrated encouraging results, with increased HIV knowledge levels following short educational sessions. Further work is required to assess the success of VAC members in disseminating this HIV education to their communities, as well as up-scaling this pilot study to other regions in Tanzania with different misconceptions.

Risk factors for HIV-1 infection in a longitudinal, prospective cohort of adults from the Mbeya Region, Tanzania

BACKGROUND

To control the global HIV epidemic, targeted interventions to reduce the incidence of HIV infections are urgently needed until an effective HIV vaccine is available. This study describes HIV-1 incidence and associated risk factors in a general population cohort of adults from Mbeya region, Tanzania, who participated in a vaccine preparedness study.

METHODS

We conducted a closed prospective cohort study with 6-monthly follow-up from 2002 to 2006 enrolling adults from the general population. HIV-1 incidence and risk factors for HIV-1 acquisition were analyzed using Cox regression.

RESULTS

We observed 2578 seronegative participants for a mean period of 3.06 person years (PY) (7471 PY in total). Overall HIV-1 incidence was 1.35 per 100 PY (95% confidence interval [CI], 1.10-1.64/100 PY). The highest overall HIV-1 incidence was found in females from Itende village (1.55 per 100 PY; 95% CI, 0.99-2.30/100 PY); the highest age-specific incidence was observed in semiurban males aged 30 to 34 years (2.75 per 100 PY; 95% CI, 0.75-7.04). HIV-1 acquisition was independently associated with female gender (hazard ratio [HR], 1.64; 95% CI, 1.05-2.57), younger age at enrollment (age 18-19 versus 35-39 years: HR, 0.29; 95% CI, 0.11-0.75), alcohol consumption (almost daily versus none: HR, 2.01; 95% CI, 1.00-4.07), education level (secondary school versus none: HR, 0.39; 95% CI, 0.17-0.89), and number of lifetime sex partners (more than five versus one: HR, 2.22; 95% CI, 1.13-4.36).

CONCLUSIONS

A high incidence of HIV was observed in this cohort, and incident infection was strongly associated with young age, alcohol consumption, low school education level, and number of sex partners. Targeted interventions are needed to address the elevated risk associated with these factors.

Incidence of HIV in Windhoek, Namibia: demographic and socio-economic associations

Objective

To estimate HIV incidence and prevalence in Windhoek, Namibia and to analyze socio-economic factors related to HIV infection.

Method

In 2006/7, baseline surveys were performed with 1,753 private households living in the greater Windhoek area; follow-up visits took place in 2008 and 2009. Face-to-face socio-economic questionnaires were administrated by trained interviewers; biomedical markers were collected by nurses; GPS codes of household residences were recorded.

Results

The HIV prevalence in the population (aged>12 years) was 11.8% in 2006/7 and 14.6% in 2009. HIV incidence between 2007 and 2009 was 2.4 per 100 person year (95%CI = 1.9–2.9). HIV incidence and prevalence were higher in female populations. HIV incidence appeared non-associated with any socioeconomic factor, indicating universal risk for the population. For women a positive trend was found between low per-capita consumption and HIV acquisition. A HIV knowledge score was strongly associated with HIV incidence for both men and women. High HIV prevalence and incidence was concentrated in the north-western part of the city, an area with lower HIV knowledge, higher HIV risk perception and lower per-capita consumption.

Discussion

The HIV incidence and prevalence figures do not suggest a declining epidemic in Windhoek. Higher vulnerability of women is recorded, most likely related to economic dependency and increasing transactional sex in Namibia. The lack of relation between HIV incidence and socio-economic factors confirms HIV risks for the overall urban community. Appropriate knowledge is strongly associated to lower HIV incidence and prevalence, underscoring the importance of continuous information and education activities for prevention of infection. Geographical areas were identified that would require prioritized HIV campaigning.

More on the cohort-component model of population projection in the context of HIV/AIDS: A Leslie matrix representation and new estimates

This article presents an extension of the cohort-component model of population projection (CCMPP) first formulated by Heuveline (2003) that is capable of modeling a population affected by HIV. Heuveline proposes a maximum likelihood approach to estimate the age profile of HIV incidence that produced the HIV epidemics in East Africa during the 1990s. We extend this work by developing the Leslie matrix representation of the CCMPP, which greatly facilitates the implementation of the model for parameter estimation and projection. The Leslie matrix also contains information about the stable tendencies of the corresponding population, such as the stable age distribution and time to stability. Another contribution of this work is that we update the sources of data used to estimate the parameters, and use these data to estimate a modified version of the CCMPP that includes (estimated) parameters governing the survival experience of the infected population. A further application of the model to a small population with high HIV prevalence in rural South Africa is presented as an additional demonstration. This work lays the foundation for development of more robust and flexible Bayesian estimation methods that will greatly enhance the utility of this and similar models.

Pathology practice in a resource-poor setting: Mwanza, Tanzania

Practicing pathology in a resource-poor setting presents many challenges that are unfamiliar to pathologists in developed countries. Typically, the number of pathologists in a resource-poor country is small, even as a percentage of the total medical workforce. Although pathology should play a central role in the delivery of appropriate health care to the patient, this role is often hidden and not well recognized by patients, clinical colleagues, or other stakeholders, such as administrators and politicians. The public tends to think of the pathologist as the "Doctor of the Dead." The financial rewards are also small. Consequently, it is difficult to recruit physicians into pathology. The lack of human and material resources allocated to pathology leads inevitably to a large gap in health care for many patients, with an unmeasured negative effect, at both the individual and societal levels. Correct management of the patient, even when available, is not administered because of the lack of pathologic information. Surgery may be performed without the benefit of preoperative or postoperative pathologic confirmation of the diagnosis, let alone identification of important prognostic information. The pathologist plays a key role as an educator in developing countries to medical students, allied health professionals, and medical colleagues and is, therefore, called upon to provide many hours of teaching. The pathologist is uniquely qualified to provide knowledge and understanding regarding the diseases in the region where he or she practices. Although many of these challenges are universal, they are perhaps nowhere more acute than in resource-poor settings.

The impact of mobility on HIV control: a modelling study

Mobility is associated with HIV due to more risky sexual behaviour of mobile groups such as travellers and migrants. Limited participation of such groups may reduce the effectiveness of HIV interventions disproportionally. The established STDSIM model, which simulates transmission and control of HIV and STD, was extended to simulate mobility patterns based on data from Tanzania. We explored the impact of non-participation of mobile groups (travellers and recent migrants) on the effectiveness of two interventions: condom promotion and health education aiming at partner reduction. If mobile groups do not participate, the effectiveness of both interventions could be reduced by 40%. The impact of targeting travellers with a combined HIV campaign is close to that of a general population intervention. In conclusion, it is important to account for possible non-participation of migrants and travellers. If non-participation is substantial, impact of interventions can be greatly improved by actively approaching these people.

Trends in HIV & syphilis prevalence and correlates of HIV infection: results from cross-sectional surveys among women attending ante-natal clinics in Northern Tanzania

Background

Sentinel surveillance for HIV in ante-natal clinics (ANC) remains the primary method for collecting timely trend data on HIV prevalence in most of sub-Saharan Africa. We describe prevalence of HIV and syphilis infection and trends over time in HIV prevalence among women attending ante-natal clinics (ANC) in Magu district and Mwanza city, part of Mwanza region in Northern Tanzania. HIV prevalence from ANC surveys in 2000 and 2002 was 10.5% and 10.8% respectively. In previous rounds urban residence, residential mobility, the length of time sexually active before marriage, time since marriage and age of the partner were associated with HIV infection.

Methods

A third round of HIV sentinel surveillance was conducted at ante-natal clinics in Mwanza region, Tanzania during 2006. We interviewed women attending 27 ante-natal clinics. In 15 clinics we also anonymously tested women for syphilis and HIV infection and linked these results to the questionnaire data.

Results

HIV prevalence was 7.6% overall in 2006 and 7.4% at the 11 clinics used in previous rounds. Geographical variations in HIV prevalence, apparent in previous rounds, have largely disappeared but syphilis prevalence is still higher in rural clinics. HIV prevalence has declined in urban clinics and is stable in rural clinics. The correlates of HIV infection have changed over time. In this round older age, lower gravidity, remarriage, duration of marriage, sexual activity before marriage, long interval between last birth and pregnancy and child death were all associated with infection.

Conclusions

HIV prevalence trends concur with results from a community-based cohort in the region. Correlates of HIV infection have also changed and more proximate, individual level factors are now more important, in line with the changing epidemiology of infection in this population.

HIV-1 incidence rates and risk factors in agricultural workers and dependents in rural Kenya: 36-month follow-up of the Kericho HIV cohort study

BACKGROUND

Incidence data from prospective cohort studies using rigorous laboratory methods are important in designing and evaluating HIV vaccine and therapeutic clinical trials and health care programs. We report 36-month HIV-1 incidence rates and demographic and psychosocial risks from the Kericho cohort in rural Kenya's southern Rift Valley Province.

METHODS

Thirty-six month, prospective, closed, observational cohort study of adult plantation workers and dependents followed biannually. HIV-1 incidence rates per 100 person-years (py) were calculated, and Cox regression analyses were used to estimate hazards ratios (HR) associated with seroconversion.

RESULTS

Two thousand four hundred volunteers (mean age +/- SD = 30.1 +/- 8.5 years; 36.5% women) participated. Twenty-nine new HIV cases were identified in year 1 of follow-up, which increased to cumulative totals of 49 and 63 cases in years 2 and 3, respectively. The corresponding 1-, 2-, and 3-year incidence rates were 1.41 [95% confidence interval (CI) = 0.95-2.02], 1.16 (95% CI = 0.86-1.54), and 1.00 (95% CI = 0.77-1.28) per 100 py. Risk factors associated with HIV seroconversion included the following: of the Luo tribe (HR = 3.31; 95% CI = 1.65-6.63), marriage more than once (HR = 2.83; 95% CI = 1.20-6.69), self-reported male circumcision (HR = 0.32; 95% CI = 0.17-0.60), history of sexually transmitted infection (HR = 2.40; 95% CI = 1.09-5.26), history of substance abuse during sex (HR = 2.44; 95% CI = 1.16-5.13), and history of transactional sex (HR = 3.30; 95% CI = 1.79-6.09).

CONCLUSIONS

HIV-1 incidence rates were relatively low in adult plantation workers and dependents in rural Kenya. Cohorts including higher risk populations (eg, commercial sex workers) warrant consideration for regional HIV preventive vaccine trials. Even low incidence, well-described cohorts generate valuable epidemiological clinical trial data.

Doubts, denial and divine intervention: understanding delayed attendance and poor retention rates at a HIV treatment programme in rural Tanzania

Irregular or delayed attendance at HIV treatment clinics among HIV-positive individuals can have negative implications for clinical outcomes and may ultimately undermine the effectiveness of national treatment programmes. This study explores factors influencing attendance at HIV clinic appointments among patients in a rural ward in north-west Tanzania. Forty-two in-depth interviews (IDI) and four focus group discussions were conducted with HIV-infected persons who had been referred to a nearby antiretroviral therapy (ART) clinic, and IDI were undertaken with 11 healthcare workers involved in diagnosis, referral and care of HIV-positive patients. The Health Belief Model was applied to explore the role of health-related beliefs and the perceived barriers and benefits associated with regular clinic attendance. Perceived susceptibility to HIV-related illnesses emerged as an important factor influencing clinic attendance, and was often manifest through expressions of acceptance or denial of HIV status and knowledge of HIV disease progression. Denial of HIV status was often associated with using alternative healers, and could occur prior to, during, or after starting ART. Perceptions of illness severity also influenced HIV clinic attendance, and often evolved in relation to changes in physical symptoms. Barriers to clinic attendance frequently included health systems factors, while physical and social benefits encouraged regular clinic attendance. Self-confidence in being able to sustain clinic attendance was often determined by patients' expectations or experiences of family support. These findings suggest that multi-faceted interventions are required to promote regular HIV clinic attendance, including on-going education, counselling and support in both clinic and community settings. These interventions also need to recognise the evolving needs of patients that accompany changes in physical health, and should address local beliefs around HIV aetiology. Decentralisation of HIV services to rural communities should be considered as a priority to redress the balance between perceived barriers to, and benefits of accessing HIV treatment programmes.

Prevalence and incidence of HIV-1 and HIV-2 before, during and after a civil war in an occupational cohort in Guinea-Bissau, West Africa

OBJECTIVES

To study prevalence and incidence of HIV-1 and HIV-2 between 1990 and 2007 and to examine impact of the civil war in 1998-1999. We also wanted to investigate possible interaction between HIV-1 and HIV-2.

DESIGN

Open prospective cohort study of 4592 police officers in Guinea-Bissau, West Africa.

METHODS

Analysis of HIV-1 and HIV-2 prevalence and incidence divided in 2-3 years time strata.

RESULTS

HIV-1 prevalence (including HIV-1/HIV-2 dual reactivity) increased gradually from 0.6 to 3.6% before the war and was 9.5% in the first serosurvey after the war. HIV-1 incidence more than doubled during and shortly after the war, from 0.50 to 1.22 per 100 person-years. Both prevalence and incidence of HIV-1 decreased in the following periods after the war. HIV-2 prevalence decreased from 13.4 to 6.2% during the entire study period and HIV-2 incidence decreased from 1.38 to 0.18 per 100 person-years. Adjusted incidence rate ratios of HIV-1 incidence in HIV-2-positive participants compared with HIV-negative participants ranged from 1.02 to 1.18 (not significant) depending on the confounding variables included.

CONCLUSION

HIV-1 has increased, whereas HIV-2 has decreased and the risk of acquiring HIV-1 is now more than four times higher as compared with HIV-2. The civil war in 1998-1999 appears to have induced a temporary increase in HIV-1 transmission, but now a stabilization of HIV-1 incidence and prevalence seems to have taken place. There was no evidence of a protective effect of HIV-2 against HIV-1 infection.

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.

Impact of an intensive HIV prevention programme for female sex workers on HIV prevalence among antenatal clinic attenders in Karnataka state, south India: an ecological analysis

OBJECTIVES

To examine the impact of an intensive HIV preventive intervention (IPI) among female sex workers (FSW) on community HIV transmission, as represented by HIV prevalence among young antenatal clinic (ANC) attenders in Karnataka state, south India.

METHODS

The IPI was initiated in 18 of the 27 districts in Karnataka in 2003, and was generally at scale by mid-2005, covering over 80% of the urban FSW population. We examined trends over time in HIV prevalence from annual HIV surveillance conducted among ANC attenders in Karnataka under the age of 25 years from 2003 to 2007, comparing the IPI with the other districts.

RESULTS

Overall, HIV prevalence among ANC attenders under 25 years of age declined from 1.40% to 0.77%. In a multivariate model, the decline in HIV prevalence in the IPI districts compared to the other districts was statistically significant (P = 0.01), with an adjusted annual odds ratio of 0.88 (95% CI 0.79-0.97). The decline in standardized HIV prevalence in the IPI districts over the period was 56%, compared to 5% in the non-IPI districts.

CONCLUSIONS

Although this analysis is limited by lack of precise comparative data on intervention coverage and intensity, it supports the notion that scaled-up, intensive, targeted HIV preventive interventions among high-risk groups can have a measurable and relatively rapid impact on HIV transmission in the general population, particularly young sexually active populations as represented by ANC attenders. Such focused intervention programmes should be rapidly taken to scale in all HIV epidemics, and especially in concentrated epidemics such as in India.

Uptake of HIV voluntary counselling and testing services in rural Tanzania: implications for effective HIV prevention and equitable access to treatment

OBJECTIVE

To describe the associations between socio-demographic, behavioural and clinical characteristics and the use of HIV voluntary counselling and testing (VCT) services among residents in a rural ward in Tanzania.

METHODS

Eight thousand nine hundred and seventy participants from a community-based cohort were interviewed, provided blood for research HIV testing, and were offered VCT. Univariate and multivariate logistic regression was used to identify socio-demographic, clinical and behavioural factors associated with VCT use.

RESULTS

Although 31% (1246/3980) of men and 24% (1195/4990) of women expressed an interest in the service, only 12% of men and 7% of women subsequently completed VCT. Socio-demographic factors, such as marital status, area of residence, religion and ethnicity influenced VCT completion among males and females in different ways, while self-perceived risk of HIV, prior knowledge of VCT, and sex with a high-risk partner emerged as important predictors of VCT completion among both sexes. Among males only, those infected with HIV for 5 years or less tended to self-select for VCT compared to HIV-negatives (adjusted odds ratio = 1.43; 95% CI: 0.99-2.14). This contributed to a higher proportion of HIV-positive males knowing their status compared to HIV-positive females.

CONCLUSIONS

In this setting, a disproportionate number of HIV-positive women are failing to learn their status, which has implications for equitable access to onward referral for care and treatment services. Evidence that some high-risk behaviours may prompt VCT use is encouraging, although further interventions are required to improve knowledge about HIV risk and the benefits of VCT. Targeted interventions are also needed to promote VCT uptake among married women and rural residents.

Estimating incidence from prevalence in generalised HIV epidemics: methods and validation

BACKGROUND

HIV surveillance of generalised epidemics in Africa primarily relies on prevalence at antenatal clinics, but estimates of incidence in the general population would be more useful. Repeated cross-sectional measures of HIV prevalence are now becoming available for general populations in many countries, and we aim to develop and validate methods that use these data to estimate HIV incidence.

METHODS AND FINDINGS

Two methods were developed that decompose observed changes in prevalence between two serosurveys into the contributions of new infections and mortality. Method 1 uses cohort mortality rates, and method 2 uses information on survival after infection. The performance of these two methods was assessed using simulated data from a mathematical model and actual data from three community-based cohort studies in Africa. Comparison with simulated data indicated that these methods can accurately estimates incidence rates and changes in incidence in a variety of epidemic conditions. Method 1 is simple to implement but relies on locally appropriate mortality data, whilst method 2 can make use of the same survival distribution in a wide range of scenarios. The estimates from both methods are within the 95% confidence intervals of almost all actual measurements of HIV incidence in adults and young people, and the patterns of incidence over age are correctly captured.

CONCLUSIONS

It is possible to estimate incidence from cross-sectional prevalence data with sufficient accuracy to monitor the HIV epidemic. Although these methods will theoretically work in any context, we have able to test them only in southern and eastern Africa, where HIV epidemics are mature and generalised. The choice of method will depend on the local availability of HIV mortality data.

Survival after HIV infection in the pre-antiretroviral therapy era in a rural Tanzanian cohort

BACKGROUND

Survival patterns after HIV infection in African populations in the era before antiretroviral therapy (ART) form an important baseline for measuring future successes of treatment programmes. Few studies have followed seroconverters for 10 or more years to describe such patterns.

METHODS

The Kisesa open cohort study conducted four rounds of village-based HIV testing and 20 rounds of household-based demographic surveillance between 1994 and 2006. Approximate infection dates were established for individual seroconverters by allocating a date between the last negative and first positive test. Person-years lived post-infection were computed, allowing for left truncation and right censoring, and Kaplan-Meier survival functions were constructed, truncating the analysis at the start of 2005 when ART first became available in the community. Weibull models were fitted to estimate median survival time, and parametric regression methods were used to investigate the influence of sex and age at infection.

RESULTS

A total of 369 seroconverters were identified, providing 890 person-years of follow-up during which 44 deaths were observed. The Kaplan-Meier function showed 67% surviving 9 years post-infection, and the overall predicted median survival was 11.5 years. Survival was strongly related to age at infection (hazard ratio 1.06 for each additional year of age, and weakly to sex. A strong effect of age was evident even after allowing for mortality from non-HIV-related causes using cause deletion methods to estimate net mortality.

CONCLUSION

The survival of HIV-infected individuals was comparable to that reported in developed country studies before the introduction of HAART. Survival patterns in Kisesa are marginally more favourable than those reported in cohort studies in Uganda.