Age- and sex-specific HIV-1 prevalence in the urban community setting of Addis Ababa, Ethiopia

ABO blood groups and risk of human immunodeficiency virus infection: A systematic review and meta-analysis

The last few decades have seen a pandemic of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS), which continues to cause substantial morbidity and mortality. ABO blood groups are anthropological and genetic characteristics of a population whose associations with HIV infection are still controversial. This systematic review with meta-analysis was undertaken to investigate whether certain blood groups may have associations with HIV infection. PubMed, Scopus and Web of Science databases were systematically searched as of 6 September 2021. Grey literature was identified through screening Google Scholar, and reference lists of relevant studies. All observational studies providing data on ABO blood group distribution among HIV-infected and uninfected participants were included. Using a random effect model, risk ratios (RR) and 95% confidence intervals (CIs) were pooled to quantify this relationship. Fifty eligible studies with a total of 3,068,244 participants and 6508 HIV-infected cases were included. The overall analysis found that blood group AB increased the risk of HIV infection by 19% as compared with non-AB blood groups (RR = 1.19, 95% CI: 1.03-1.39, p = 0.02). Pooled estimates for other blood groups failed to reach statistical significance. Subgroup analyses identified a positive relationship between AB blood group and HIV infection within Asia, patient populations (as opposed to blood donors and general populations), studies with lower sample sizes, high-income countries and studies with a moderate quality score. The sequential omission and re-analysis of studies within sensitivity analyses produced no change in the overall pooled effect. In conclusion, this study identified that blood group AB carriers were more susceptible to HIV infection. Future investigations should be directed toward clarification of the exact role of ABO blood groups in HIV infection and the possible underlying mechanisms.

Trends and epidemiological analysis of hepatitis B virus, hepatitis C virus, human immunodeficiency virus, and human T-cell lymphotropic virus among Iranian blood donors: strategies for improving blood safety

BACKGROUND

Blood transfusion is associated with potential risks of transfusion-transmitted infections (TTIs). Different strategies are needed to monitor blood safety and screen the donors' efficacy, such as evaluation of the prevalence and trends of TTIs. This study was conducted to evaluate the prevalence and trends of TTIs, including hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and human T-cell lymphotropic virus (HTLV 1/2), and the impact of the donors' characteristics such as age, sex, and donor status on the prevalence of TTIs in blood donors in seven large provinces of Iran from 2010 to 2018.

METHODS

This study was conducted on the data collected from all blood donations in seven Iranian Blood Transfusion Centers including Ardabil, Alborz, Guilan, West Azarbaijan, North, Razavi, and South Khorasan from April 2010 to March 2018. Demographic characteristics, number of donations, donor status, and screening and confirmatory serological results of all blood donations were collected from Iranian Blood Transfusion Organizations (IBTO) national database. The prevalence and trend of HBV, HCV, HIV, and HTLV 1/2 infections were reported according to the donation year and donor's characteristics.

RESULTS

The analysis of the prevalence and trend of TTIs in 3,622,860 blood donors showed a significant decreasing trend in first-time and regular donors. Additionally, compared to first- time donors, regular donors made safer blood donations with lower risks of HBV, HIV, HCV and HTLV 1/2 (P < 0.0001). Although the prevalence of HTLV 1/2 and HBV was higher in females, TTIs had a significant decreasing trend in males and females. Finally, it was found that the prevalence of HBV and HTLV 1/2 increased with age up to 40-49 years and then decreased thereafter.

CONCLUSIONS

The decreasing trends of TTIs in Iranian donors during 9 years may indicate that the various strategies implemented by IBTO have been effective in recent years. Other factors such as a decrease in the prevalence of specific TTIs in the general population might have also contributed to these declines.

HIV Prevalence Correlates with High-Risk Sexual Behavior in Ethiopia's Regions

BACKGROUND

HIV prevalence varies between 0.9 and 6.5% in Ethiopia's eleven regions. Little has been published examining the reasons for this variation.

METHODS

We evaluated the relationship between HIV prevalence by region and a range of risk factors in the 2005 and 2011 Ethiopian Demographic Health Surveys. Pearson's correlation was used to assess the relationship between HIV prevalence and each variable.

RESULTS

There was a strong association between HIV prevalence and three markers of sexual risk: mean lifetime number of partners (men: r = 0.87; P < 0.001; women: r = 0.60; P = 0.05); reporting sex with a non-married, non-cohabiting partner (men: r = 0.92; P < 0.001, women r = 0.93; P < 0.001); and premarital sex. Condom usage and HIV testing were positively associated with HIV prevalence, while the prevalence of circumcision, polygamy, age at sexual debut and male migration were not associated with HIV prevalence.

CONCLUSION

Variation in sexual behavior may contribute to the large variations in HIV prevalence by region in Ethiopia. Population-level interventions to reduce risky sexual behavior in high HIV incidence regions should be considered.

Epidemiological and demographic HIV/AIDS projections: South Africa

The Epidemic Projection Package (EPP) recently developed by the UNAIDS Reference Group on Estimates, Models and Projections and the Spectrum model program developed by the Futures Group were used to model the South African HIV epidemic, project future trends in HIV/AIDS and estimate the demographic impact of AIDS. The national HIV prevalence surveys among pregnant women from 1990-2001 and the first national, population-based HIV survey in 2002 served as the data sets used to calibrate the input HIV prevalence values for the model. The scenario created by the model showed that a dramatic rise in HIV prevalence during the 1990s has peaked in 2002 with 4.69 million infected people and it is projected that the epidemic in South Africa has now begun to level off. Adult (15-49 years) incidence rates have decreased substantially in the past five years since 1997 (4.2%) and are expected to reach a level of 1.7% in 2003. The annual number of deaths due to AIDS is projected to peak with 487 320 AIDS deaths in the year 2008. By 2020, the total population of South Africa is expected to be 23% smaller than it would be without AIDS, however, a negative population growth rate is not expected during the projection period. Life expectancy at birth is expected to hit a low of 45.6 years in the time period 2005-2010, which is 22 years less than it would have been in the absence of AIDS. Ten years from now over 2.5 million AIDS orphans are projected for South Africa. Models play an important role in estimating HIV variables that are difficult to measure. Projections of the future HIV/AIDS burden in South Africa underscore the importance of acting now to reduce the number of new infections and plan for medical and social care needs.

Modelling HIV incidence and survival from age-specific seroprevalence after antiretroviral treatment scale-up in rural South Africa

OBJECTIVE

Our study uses sex-specific and age-specific HIV prevalence data from an ongoing population-based demographic and HIV survey to infer HIV incidence and survival in rural KwaZulu-Natal between 2003 and 2011, a period when antiretroviral treatment (ART) was rolled out on a large scale.

DESIGN

Catalytic mathematical model for estimating HIV incidence and differential survival in HIV-infected persons on multiple rounds of HIV seroprevalence.

METHODS

We evaluate trends of HIV incidence and survival by estimating parameters separately for women and men aged 15-49 years during three calendar periods (2003-2005, 2006-2008, 2009-2011) reflecting increasing ART coverage. We compare model-based estimates of HIV incidence with observed cohort-based estimates from the longitudinal HIV surveillance.

RESULTS

Median survival after HIV infection increased significantly between 2003-2005 and 2009-2011 from 10.0 [95% confidence interval (CI) 8.8-11.2] to 14.2 (95% CI 12.6-15.8) years in women (P < 0.001) and from 10.0 (95% CI 9.2-10.8) to 14.0 (95% CI 10.6-17.4) years in men (P = 0.02). Our model suggests no statistically significant reduction of HIV incidence in the age-group 15-49 years in 2009-2011 compared with 2003-2005. Age-specific and sex-specific model-based HIV incidence estimates were in good agreement with observed cohort-based estimates from the ongoing HIV surveillance.

CONCLUSION

Our catalytic modelling approach using cross-sectional age-specific HIV prevalence data could be useful to monitor trends of HIV incidence and survival in other African settings with a high ART coverage.

A history of chagas disease transmission, control, and re-emergence in peri-rural La Joya, Peru

Background

The history of Chagas disease control in Peru and many other nations is marked by scattered and poorly documented vector control campaigns. The complexities of human migration and sporadic control campaigns complicate evaluation of the burden of Chagas disease and dynamics of Trypanosoma cruzi transmission.

Methodology/Principal Findings

We conducted a cross-sectional serological and entomological study to evaluate temporal and spatial patterns of T. cruzi transmission in a peri-rural region of La Joya, Peru. We use a multivariate catalytic model and Bayesian methods to estimate incidence of infection over time and thereby elucidate the complex history of transmission in the area. Of 1,333 study participants, 101 (7.6%; 95% CI: 6.2–9.0%) were confirmed T. cruzi seropositive. Spatial clustering of parasitic infection was found in vector insects, but not in human cases. Expanded catalytic models suggest that transmission was interrupted in the study area in 1996 (95% credible interval: 1991–2000), with a resultant decline in the average annual incidence of infection from 0.9% (95% credible interval: 0.6–1.3%) to 0.1% (95% credible interval: 0.005–0.3%). Through a search of archival newspaper reports, we uncovered documentation of a 1995 vector control campaign, and thereby independently validated the model estimates.

Conclusions/Significance

High levels of T. cruzi transmission had been ongoing in peri-rural La Joya prior to interruption of parasite transmission through a little-documented vector control campaign in 1995. Despite the efficacy of the 1995 control campaign, T. cruzi was rapidly reemerging in vector populations in La Joya, emphasizing the need for continuing surveillance and control at the rural-urban interface.

The historically rural problem of Chagas disease is increasing in urban areas in Latin America. Peri-rural development may play a critical role in the urbanization of Chagas disease and other parasitic infections. We conducted a cross-sectional study in an urbanizing rural area in southern Peru, and we encountered a complex history of Chagas disease in this peri-rural environment. Specifically, we discovered: (1) long-standing parasite transmission leading to substantial burden of infection; (2) interruption in parasite transmission resulting from an undocumented insecticide application campaign; (3) relatively rapid re-emergence of parasite-infected vector insects resulting from an unsustained control campaign; (4) extensive migration among peri-rural inhabitants. Long-standing parasite infection in peri-rural areas with highly mobile populations provides a plausible mechanism for the expansion of parasite transmission to nearby urban centers. Lack of commitment to control campaigns in peri-rural areas may have unforeseen and undesired consequences for nearby urban centers. Novel methods and perspectives are needed to address the complexities of human migration and erratic interventions.

Non-vertical HIV transmission to children in sub-Saharan Africa

This review considers whether HIV prevalence data on children in sub-Saharan Africa support the hypothesis that blood exposures account for a large proportion of HIV infections in Africa. Data from a systematic search on HIV-infected children support two analyses. In 25 studies where the mothers' HIV status was not matched with data on each child (excluding non-representative samples of children), the observed prevalence in children in 20 studies was greater than expected from vertical transmission. The population-weighted difference – 1.3% – was approximately one-third of observed prevalence in children. In 32 studies that match HIV-positive children with HIV-negative mothers, 406 discordant mother–child pairs were identified, and in studies identifying at least five non-vertical infections in children, 17.5% of HIV-positive children had HIV-negative mothers. In discussing an important role for unsafe health care in exceptionally rapid HIV transmission in Africa, leading AIDS researchers cite low HIV prevalence in children not yet sexually active. The assumption that childhood HIV prevalence would increase with age in children, if injections transmitted HIV is shown to be erroneous; it fails to account for early mortality in HIV-positive children. Evidence of child-to-child HIV transmission supports the theory that nosocomial infections are important to the AIDS pandemic, and procedures more prevalent than blood transfusions, such as injections, are likely involved.

Steep declines in population-level AIDS mortality following the introduction of antiretroviral therapy in Addis Ababa, Ethiopia

OBJECTIVES

Assessments of population-level effects of antiretroviral therapy (ART) programmes in Africa are rare. We use data from burial sites to estimate trends in adult AIDS mortality and the mitigating effects of ART in Addis Ababa. ART has been available since 2003, and for free since 2005.

METHODS

To substitute for deficient vital registration, we use surveillance of burials at all cemeteries. We present trends in all-cause mortality, and estimate AIDS mortality (ages 20-64 years) from lay reports of causes of death. These lay reports are first used as a diagnostic test for the true cause of death. As reference standard, we use the cause of death established via verbal autopsy interviews conducted in 2004. The positive predictive value and sensitivity are subsequently used as anchors to estimate the number of AIDS deaths for the period 2001-2007. Estimates are compared with Spectrum projections.

RESULTS

Between 2001 and 2005, the number of AIDS deaths declined by 21.9 and 9.3% for men and women, respectively. Between 2005 and 2007, the number of AIDS deaths declined by 38.2 for men and 42.9% for women. Compared with the expected number in the absence of ART, the reduction in AIDS deaths in 2007 is estimated to be between 56.8 and 63.3%, depending on the coverage of the burial surveillance.

CONCLUSION

Five years into the ART programme, adult AIDS mortality has been reduced by more than half. Following the free provision of ART in 2005, the decline accelerated and became more sex balanced. Substantial AIDS mortality, however, persists.

Enrollment and retention of HIV discordant couples in Lusaka, Zambia

BACKGROUND

Biased enrollment and attrition compromise the power of clinical trials and limit generalizability of findings. We identify predictors of enrollment and retention for HIV-discordant couples enrolled in prospective studies in Zambia.

PRINCIPAL FINDINGS

A total of 1995 discordant couples were invited to enroll. Predictors of nonenrollment, loss to follow-up, and missed appointments were evaluated using multivariate models. MF couples were more likely to be eligible and to enroll and less likely to be lost to follow-up than FM couples. Substantial losses to follow-up occurred between testing and enrollment (21.3% of MF and 28.1% of FM) and between enrollment and the first follow-up visit (24.9% of MF and 30.5% of FM). Among MF and FM couples, residence far from the clinic, younger age, and women's age at first intercourse </=17 years were predictive of attrition. No income, </=2 lifetime sex partners, no history of sexually transmitted infection in women, and recent extramarital contact in their male partners predicted attrition in FM couples.

CONCLUSIONS

Discordant couples are critical to observational studies and clinical trials to prevent male-to-female and female-to-male transmission. Retention biases must be taken into account during analysis. Run-in designs that delay randomization may improve retention in clinical trials.

HIV-1 Subtype C gag-specific T-cell responses in relation to human leukocyte antigens in a diverse population of HIV-infected Ethiopians

Knowledge of the most dominant T-cell epitopes in the context of the local human leukocyte antigen (HLA) background is a prerequisite for the development of an effective HIV vaccine. In 100 Ethiopian subjects, 16 different HLA-A, 23 HLA-B, and 12 HLA-C specificities were observed. Ninety-four percent of the population carried at least 1 of the 5 most common HLA-A and/or HLA-B specificities. HIV-specific T-cell responses were measured in 48 HIV-infected Ethiopian subjects representing a wide range of ethnicities in Ethiopia using the interferon (IFN)-gamma enzyme-linked immunospot (Elispot) assay and 49 clade C-specific synthetic Gag peptides. Fifty-eight percent of the HIV-positive study subjects showed T-cell responses directed to 1 or more HIV Gag peptides. Most Gag-specific responses were directed against the subset of peptides spanning Gag p24. The breadth of response ranged from 1 to 9 peptides, with most (78%) individuals showing detectable responses to <3 Gag peptides. The magnitude of HIV-specific T-cell responses was not associated with HIV viral load but correlated positively with CD4 T-cell counts. The most frequently targeted Gag peptides overlapped with those previously described for HIV-1 subtype C-infected southern Africans, and therefore can be used in a multiethnic vaccine.

Quantifying HIV-1 transmission due to contaminated injections

Assessments of the importance of different routes of HIV-1 (HIV) transmission are vital for prioritization of control efforts. Lack of consistent direct data and large uncertainty in the risk of HIV transmission from HIV-contaminated injections has made quantifying the proportion of transmission caused by contaminated injections in sub-Saharan Africa difficult and unavoidably subjective. Depending on the risk assumed, estimates have ranged from 2.5% to 30% or more. We present a method based on an age-structured transmission model that allows the relative contribution of HIV-contaminated injections, and other routes of HIV transmission, to be robustly estimated, both fully quantifying and substantially reducing the associated uncertainty. To do this, we adopt a Bayesian perspective, and show how prior beliefs regarding the safety of injections and the proportion of HIV incidence due to contaminated injections should, in many cases, be substantially modified in light of age-stratified incidence and injection data, resulting in improved (posterior) estimates. Applying the method to data from rural southwest Uganda, we show that the highest estimates of the proportion of incidence due to injections are reduced from 15.5% (95% credible interval) (0.7%, 44.9%) to 5.2% (0.5%, 17.0%) if random mixing is assumed, and from 14.6% (0.7%, 42.5%) to 11.8% (1.2%, 32.5%) under assortative mixing. Lower, and more widely accepted, estimates remain largely unchanged, between 1% and 3% (0.1-6.3%). Although important uncertainty remains, our analysis shows that in rural Uganda, contaminated injections are unlikely to account for a large proportion of HIV incidence. This result is likely to be generalizable to many other populations in sub-Saharan Africa.

HIV/AIDS in Ethiopia: where is the epidemic heading?

OBJECTIVES

A possible decline in prevalence of HIV in some sub-Saharan African countries has been reported recently. The present study aimed to evaluate the prevalence and incidence of HIV and behavioural data to investigate trends in HIV/AIDS in Ethiopia.

METHODS

A review was conducted of published reports and literature, raw and modelled (using Epidemic Projection Package and Spectrum software) surveillance data and estimates from antenatal clinics (ANCs) and data from voluntary counselling and testing centres. Observations were restricted to the adult population.

RESULTS

Between 2001 and 2003, more ANC sites showed a decline than a rise in HIV prevalence, but most lacked statistical significance. Modelled data suggested a rise in prevalence of HIV in rural areas (2003: 2.6%) and in all Ethiopia (2003: 4.4%), but a stable or declining prevalence in Addis Ababa (2003: 14.6%) and other urban areas (2003: 11.8%). Modelled HIV incidence, inferred from prevalence changes, showed a slowly rising trend in Addis Ababa (2003: 2.0%), other urban areas (2003: 1.7%), and rural Ethiopia (2003: 0.46%). The total burden of HIV/AIDS is expected also to rise substantially due to population growth. In Addis Ababa, crude data on HIV prevalence from ANCs too suggested a falling trend. Voluntary counselling and testing data from 2002 to 2004 supported this trend but indicated a mixed trend pattern for high risk behaviour. No other serial behavioural trend data were available.

CONCLUSIONS

Lack of quality data on behavioural trends impedes the interpretation of prevalence and incidence data in Ethiopia. Modelled data suggest an expanding HIV epidemic in rural and all Ethiopia, but a possible decline in some urban areas. Crude site prevalence values may be more sensitive to acute changes, possibly indicating a slowing/reversal of the epidemic's expansion.

HIV-1 subtype C dissemination in southern Brazil

OBJECTIVES

To describe the molecular and epidemiological profile of HIV-1 in patients followed at the University Hospital of Rio Grande, Brazil.

DESIGN AND METHODS

A cross-sectional study was conducted from September to December 2002. Plasma viral RNA of 85 patients was extracted and protease and reverse transcriptase genes were polymerase chain reaction-amplified and sequenced. Sequences were subtyped and examined to antiretroviral resistance mutations. Laboratory data and past history of antiretroviral treatment were also collected.

RESULTS

Most viruses were either subtype B (42%) or subtype C (45%). No risk behaviour, sexual orientation or laboratory parameter was associated with any specific subtype, but subtype C tended to be more frequently found in women (P = 0.06). The prevalence of subtype C has increased over the HIV/AIDS epidemic, accounting for almost 60% of cases diagnosed in 2002. Intra-subtype genetic distances were smaller in subtype C than in subtype B, suggesting a more recent introduction of the former in the epidemic. Of patients under treatment, 60% had at least one antiretroviral drug resistance mutation, but no mutation was specifically associated with any HIV-1 subtype. Only one resistance mutation each was found in drug-naive patients with subtypes B and C.

CONCLUSION

Despite the fact that subtype C appeared in southern Brazil more recently than subtype B, it is now the predominant strain in Rio Grande. The epidemic spread of subtype C could be taking place in Brazil, and possibly in south America, a phenomenon similar to that seen in other countries where this subtype is now totally dominant.

Adolescent reproductive health and awareness of HIV among rural high school students, North Western Ethiopia

Ethiopia is faced with an increasing problem from HIV infection, and the vulnerability of adolescents is a key concern. There is little information on the knowledge, attitudes and practices of this age group with respect to HIV, sexually transmitted diseases and preventive measures. We conducted a cross-sectional study among 260 students from two rural high schools in North Western Ethiopia. We found that although the general awareness of HIV was high, correct knowledge of the virus and its modes of transmission was shown in only 44% of adolescent boys and 41% of adolescent girls. Knowledge of HIV and condoms was lower among students whose parents were farmers, significant so among girls (p=0.02). Use of condoms among sexually active single male students (49%) was insufficient but was higher than among adolescents in many other African settings. Knowledge of STDs was generally low: 82% of adolescent males and 37% of adolescent females had some awareness of STDs. Almost 20% of sexually active males in the study had previously experienced an STD, almost all of whom had visited a commercial sex worker. Targeted interventions are warranted among adolescents and sex workers in Ethiopia complemented by STD treatment services.

Transmission of HIV-1 infection in sub-Saharan Africa and effect of elimination of unsafe injections

During the past year, a group has argued that unsafe injections are a major if not the main mode of HIV-1 transmission in sub-Saharan Africa. We review the main arguments used to question the epidemiological interpretations on the lead role of unsafe sex in HIV-1 transmission, and conclude there is no compelling evidence that unsafe injections are a predominant mode of HIV-1 transmission in sub-Saharan Africa. Conversely, though there is a clear need to eliminate all unsafe injections, epidemiological evidence indicates that sexual transmission continues to be by far the major mode of spread of HIV-1 in the region. Increased efforts are needed to reduce sexual transmission of HIV-1.

Recombination of HIV type 1C (C'/C") in Ethiopia: possible link of EthHIV-1C' to subtype C sequences from the high-prevalence epidemics in India and Southern Africa

The magnitude and complexity of the HIV-1 genetic diversity are major challenges for vaccine development. Investigation of the genotypes circulating in areas of high incidence, as well as their interactions, will be a milestone in the development of an efficacious vaccine. Because HIV-1 subtype C (HIV-1C) is responsible for most of the 36 million infections worldwide we investigated the HIV-1C strains circulating in Ethiopia in a retrospective, cross-sectional study. Serum samples from HIV-1-positive individuals were collected in seven Ethiopian cities and towns. Nucleotide sequences of the gag, pol, and env genes were analyzed. We performed phylogenetic analysis by the neighbor-joining and maximum-likelihood methods with sequences from 30 isolates, and we determined recombination by the bootscanning method as implemented in the SIMPLOT program. Sequence analyses of a 2600-nucleotide fragment (including the gag gene, the protease, and the 5' half of reverse transcriptase of the pol gene) and the corresponding V1V2/C2V3 envelope regions confirmed that two distinct HIV-1C genotypes (C' and C") are cocirculating in Ethiopia, as shown previously by the analysis of the C2V3 envelope region. We have identified intrasubtype recombination between the two HIV-1C genotypes, C' and C", with 6 of the 30 (20%) analyzed viruses being recombinants. The C' sequences were phylogenetically linked to the fast spreading viruses in India and southern Africa. Furthermore, all the recombinant viruses shared the C' V1V3 region of the envelope, suggesting that the prevalence of viruses with the C' envelope is increasing compared to the C" envelope. The possibility that viruses with a C' envelope have a biological advantage over the viruses with a C" envelope should be further investigated in biological and epidemiological studies.

Methods and procedures for estimating HIV/AIDS and its impact: the UNAIDS/WHO estimates for the end of 2001

BACKGROUND

The Joint United Nations Programme on HIV and AIDS (UNAIDS) and the World Health Organization (WHO) have produced country-specific estimates of HIV/AIDS biannually since 1997. These estimates are a primary source of information about the extent and spread of the HIV/AIDS epidemic and its impact. The importance of having comparable country-specific estimates of HIV/AIDS is growing as estimates are used to determine how international resources to fight HIV/AIDS will be allocated to countries.

OBJECTIVES

This paper describes the procedures and process used to make the 2001 round of UNAIDS/WHO estimates of HIV/AIDS. The paper focuses on the different approaches used to make estimates of prevalence in countries with generalized and low-level and concentrated epidemics as well as on new curve-fitting software that was developed to produce epidemic curves for each country. In addition, it presents the assumptions used (e.g. survival from infection to death, the rate of mother-to-child transmission) that are required to derive estimates of incidence and mortality in adults, as well as prevalence, incidence and mortality in children.

CONCLUSION

The paper describes the general process by which the estimation and modelling procedures have been refined and improved over time. The paper also discusses the limitations and weaknesses of the procedures and the data used to make the estimates, and suggests areas where further improvements need to be made.

HIV type 1 C and C' subclusters based on long terminal repeat sequences in the Ethiopian type 1 subtype C epidemic

While the Ethiopian HIV-1 epidemic is dominated by subtype C, two distinguishable cocirculating C genotypes have been identified based on sequences of the C2V3 envelope region. In this study we sequenced and analyzed the long terminal repeat (LTR) sequence from 22 Ethiopian HIV-1-positive individuals. The two phylogenetically distinguishable genotypes C (n = 13) and C' (n = 4) are separated by significant bootstrap values. Nucleotide differences between the two groups were identified in the NF-AT, TCF-1alpha, and SP1 transcription factor binding sites, whereas the NF-kappaB and NRE-core sequences were identical between the two groups. Five isolates that could not be classified C or C' were found to be recombinants within the LTR sequence upon boots can analysis. Comparison of all the LTR sequences with their corresponding C2V3 envelope sequence revealed four intersubtype C/C' recombinant isolates. Thus, the prevalence of C/C' recombinant viruses is well over 40%. Interestingly, the C2V3 envelope sequences of all recombinant viruses belonged to the genotype C', whereas every LTR sequence belonged to the genotype C. This result indicates that recombination between the two genotypes is unidirectional, possibly as the result of evolutionary pressure on the respective biological functions of the LTR promoter and the envelope protein.

HIV prevalence in 72 000 urban and rural male army recruits, Ethiopia

BACKGROUND

The recent estimate of around 2 million HIV-infected people in Ethiopia derives from data that are sparse, especially in the rural areas where the majority (> 85%) of the population lives. We assessed HIV prevalence in almost 72 000 army recruits who resided in urban and rural areas prior to recruitment.

METHODS

Rapid HIV tests, HIVSPOT and Determine, were conducted on blood samples drawn at enrolment from almost 10 000 urban recruits, in 1999, and 62 000 rural recruits, in 2000. Socio-demographic data from recruits were available.

RESULTS

In urban recruits, overall HIV prevalence was 7.2%, ranging from 4.3 to 10.5% depending on region. In rural recruits, overall HIV prevalence was 3.8%, but the majority were farmers (57%) and students (18%) with an HIV prevalence of 2.7% and 2.6%, respectively. (Higher) level of education in rural recruits was associated with HIV infection. Rural recruits of the Muslim religion were less likely to be HIV infected than recruits of the Orthodox Christian religion (odds ratio: 0.7; 95% confidence interval, 0.65-0.84). Urban and rural residents of Amhara region were at higher risk of HIV infection.

CONCLUSION

Prevalence in both rural and urban army recruits is below previous estimates. Geographic distribution of HIV is uneven. The impact of religion, education, and region on HIV prevalence suggests avenues for targeting HIV prevention efforts in Ethiopia.

HIV risk in relation to marriage in areas with high prevalence of HIV infection

In sub-Saharan Africa, the prevalence of HIV infection among young women is much higher than that among young men. Many women enter marriage HIV-infected, suggesting that men may be predominantly infected by their wives. Using data from cross-sectional surveys in Kisumu, Kenya, and Ndola, Zambia, in 1997, the prevalence of HIV infection at marriage was estimated from age at marriage and age- and sex-specific prevalence of HIV infection among unmarried individuals. Using a deterministic model, this prevalence was compared with measured concordance of HIV infection among recently married couples to estimate transmission probabilities within marriage and extramarital incidence of HIV infection. Over a wide range of assumptions, we estimated that at least one quarter of cases of HIV infection in recently married men were acquired from extramarital partnerships, and for both men and women, less than one half of cases of HIV infection were acquired from their spouse. In these sites, many infections in married men, even in those with HIV-infected wives, may be acquired from outside the marriage.

Mortality impact of AIDS in Addis Ababa, Ethiopia

OBJECTIVE

To measure the impact of HIV on mortality in Addis Ababa, Ethiopia.

DESIGN

A retrospective review of burials at three cemeteries, 1987-2001 and a prospective surveillance of burials at all (n = 70) cemeteries, February-May, 2001.

METHODS

The age, sex, and date of burial were recorded; in the absence of denominators, we compared the ratio of deaths of persons 25-49 versus 5-14 years of age per calendar year, using logistic regression, adjusting for sex and site. The age- and sex- specific mortality were calculated and compared with pre-HIV mortality in 1984.

RESULTS

Of 17,519 deaths, retrospectively reviewed, complete data were available for 6342 (47%) females and 7269 (53%) males. During 1987-2001, the '25-49' versus '5-14' group all-cause mortality ratio increased by 8.5% per calendar year (P < 0.05). A total of 5101 deaths were recorded in the prospective surveillance. Crude mortality rates were 9.5/1000 per year (men) and 7.1/1000 per year (women). In comparison with 1984, 5.0-times as many men and 5.3-times as many women died in the age group 35-39 years. Attributing the increase in mortality in ages 15-60 to HIV in the period 1984-2001, Ethiopian men and women have a probability of 18.8 and 17.8%, respectively, of dying of HIV before age 60.

CONCLUSION

Burials increased significantly among the '25-49', versus the '5-14' group, during the period 1987-2001. This trend, and a five-times higher mortality in 2001 than in 1984 in those aged 35-39 years demonstrate a severe impact of HIV on mortality. Continuing surveillance of burials is recommended.

HIV infection in rural villages of Cameroon

OBJECTIVE

To evaluate HIV-1 antibody seroprevalence and risk factors for HIV seropositivity in rural areas of Cameroon.

METHOD

The prevalences of HIV antibodies in 53 villages in rural Cameroon visited during May-October 2000 were determined with an HIV1/2 rapid assay, standard ELISA, and western blot. Demographic data and risk factors were elicited via face-to-face interviews with a structured questionnaire.

RESULTS

HIV seroprevalence was 5.8% (243/4156, 95% confidence interval [CI] = 5.1-6.6) overall, 6.3% (151/2394, 95% CI = 5.4-7.4) among females and 5.2% (92/1762, 95% CI = 4.3-6.4) among males. HIV seroprevalence among persons aged 15 - 70 years did not differ significantly by province (5.6% in Center, 4.5% in East, 6.9% in South, and 5.8% in South-West) ( =.10). Analysis of age- and gender-standardized prevalence by village across provinces indicated a near-significant difference (nonparametric Wilcoxon signed rank test, =.06), with highest prevalence in South-West, followed by South, Center, and East. Multivariate analysis revealed that single women were significantly more likely to be HIV seropositive than were married or widowed women. Women with a history of sexual relations while traveling were at significantly increased risk of HIV seropositivity (OR adjusted for age and marital status = 2.4, 95% CI = 1.4-9.7). Among men, those who reported ever having a sexually transmitted disease were at significantly increased risk of HIV-seropositivity (OR adjusted for age = 1.8, 95% CI = 1.1-2.8).

CONCLUSION

We have documented a wide range of HIV prevalences among rural villages of Cameroon. Age, marital status (in women) and sexual risk factors appear to be associated with HIV infection in this setting.

HIV type 1 strains from East and West Africa are intermixed in Sudan

The genetic subtypes of HIV-1 in the Sudan epidemic have not been characterized. Here we report the partial sequencing and analysis of 30 strains collected from HIV-1-positive patients and blood donors in Khartoum in 1998 and 1999. From analysis of partial pol and env sequences, it was determined that 50% were subtype D and 30% were subtype C. Of interest, some subtype D clustered with those from East Africa whereas others joined subtype D from West Africa. Subtype A, subtype B, and three unique recombinants were also found, some partially unclassifiable. One unclassified strain matched another reported previously from the Democratic Republic of Congo. Sudan borders nine other African countries, and has suffered more than 20 years of civil strife with large population displacements. The intermixing of HIV-1 subtypes previously separated in Africa may be occurring there, with the potential to generate novel new strains by recombination.

Higher prevalence of anti-HCV antibodies among HIV-positive compared to HIV-negative inhabitants of Addis Ababa, Ethiopia

Serum samples (n = 4,593) collected in 1994 as part of a representative household community survey of the population of Addis Ababa who were 0-49 years old were tested for hepatitis C (HCV) antibodies. A third generation ELISA was used for primary screening and a line immunoblot assay for confirmation. HCV antibody prevalence was 0.9% (95% CI, 0.6-1.2%) and higher among HIV-positive compared to HIV-negative individuals (4.5% vs. 0.8%, respectively, P < 0.001). Similar higher prevalence of HCV antibodies was seen among HIV-positive compared to HIV-negative antenatal care attenders (2.9% vs. 0.8%, respectively, P = 0.003, n = 1,725), and sex workers (5.3% vs. 1.3%, respectively, P = 0.02, n = 383). Such association between HCV and HIV infection has not been described previously in Africa. After stratification by HIV status, HCV prevalence among women of the general population was identical to that of sex workers, suggesting that HCV sexual transmission is not common in this population and that HIV infection does not enhance susceptibility to HCV sexual transmission.

Primary HIV-1 subtype C infection in Ethiopia

Between 1997 and 2001, 1624 Ethiopian factory workers were enrolled in prospective HIV-1 cohorts in Ethiopia, at Akaki and Wonji towns. HIV-1 seroprevalence at intake was 11.8% (Akaki) and 7.1% (Wonji). HIV-1 incidence was .75 per 100 person-years (Akaki) and .35 per 100 person-years (Wonji). During follow up, CD4 T-cell counts remained significantly lower and CD8 T-cell counts significantly higher in Ethiopian seroconverters compared with Dutch seroconverters. Viral loads were lower in Ethiopian seroconverters versus Dutch seroconverters in the first months after seroconversion, subsequently increasing to similar levels. All 20 Ethiopian seroconverters were infected with HIV-1 subtype C (15 with sub-cluster C' and 5 with sub-cluster C). Viral loads were higher in sub-cluster C'-infected Ethiopian seroconverters. One subject demonstrated a window period of at least 204 days, combined with a high preseroconversion viral load and no decline of CD4 T cells over a follow-up period of at least 3 years.

Decline in prevalence of HIV-1 infection and syphilis among young women attending antenatal care clinics in Addis Ababa, Ethiopia: results from sentinel surveillance, 1995-2001

From 1995 to 2001, five rounds of sentinel surveillance were carried out for young women attending antenatal care clinics at four health centers in Addis Ababa, the capital city of Ethiopia, to monitor trends in the prevalence of HIV infection and syphilis. Serum samples were tested for antibodies to HIV (enzyme-linked immunosorbent assay and Western blotting) and antibodies to Treponema pallidum (T. pallidum hemagglutination assay and rapid plasma reagin test). Prevalence ratios for an increase in one calendar year were estimated using log-binomial models. Between 1995 and 2001, the prevalence of HIV infection among young women (age range, 15-24 years) attending antenatal care clinics in inner city health centers declined from 24.2% to 15.1% (prevalence ratio for an increase in one calendar year, 0.91; 95% confidence interval, 0.87-0.95). No change was observed for older age groups or in outer city health centers. The decline in the prevalence of active syphilis (T. pallidum hemagglutination assay and rapid plasma reagin testing positive for antibodies to T. pallidum) was more pronounced among and also restricted to the young age groups (age range, 15-24 years) in the inner city (from 7.6% in 1995 to 1.3% in 2001; prevalence ratio, 0.69; 95% confidence interval, 0.59-0.80). The declining trends in the prevalence of HIV infection and syphilis among young women attending antenatal care clinics in the inner city are encouraging, but these findings require confirmation in future years and for other population groups.

Comparison of HIV prevalences in community-based and antenatal clinic surveys in rural Mwanza, Tanzania

OBJECTIVES

First, to compare the prevalence of HIV infection among women in the general population and antenatal clinic (ANC) attenders in rural Mwanza, Tanzania, and second, to validate a method for adjusting HIV prevalence in ANC attenders to estimate the prevalence in the general female population aged 15-44 years.

METHODS

A cross-sectional population survey was conducted in 12 rural communities of Mwanza Region between 1991 and 1992. From the same communities sequential ANC attenders were recruited on two occasions between 1991 and 1993. Consenting subjects were interviewed, examined, treated and a serum sample was tested for HIV. The HIV prevalence in women in the general population was compared with unadjusted and adjusted prevalences in ANC attenders. Parity-adjusted prevalences were obtained by applying correction factors to the observed prevalences in parous and nulliparous ANC attenders.

RESULTS

A total of 5675 women aged 15-44 years from the general population and 2265 ANC attenders had complete socio-demographic and laboratory data. Unadjusted HIV prevalence was significantly lower in ANC attenders (3.6%) than women from the general population (4.7%, P = 0.025), but after adjustment there was no significant difference between the two groups (4.6 versus 4.7%, P = 0.95).

CONCLUSION

In this rural population, the HIV prevalence in ANC attenders underestimated the prevalence among women in the general population, but this difference was eliminated by applying parity-based correction factors. Information on parity should be routinely collected in ANC-based HIV sentinel surveillance.

Study of bias in antenatal clinic HIV-1 surveillance data in a high contraceptive prevalence population in sub-Saharan Africa

OBJECTIVE

To describe patterns, sources and consequences of bias in antenatal clinic (ANC) HIV prevalence estimates in a high contraceptive prevalence population.

BACKGROUND

HIV surveillance in Africa relies on data from pregnant women attending ANCs. HIV estimates from pregnant women understate female infection levels in low income, high fertility populations. Bias in high contraceptive use, delayed sexual debut populations remains undescribed.

DESIGN AND METHOD

Comparison of parallel cross-sectional population and antenatal survey data from rural Zimbabwe, where 60% of women are recent contraceptive users.

RESULTS

HIV prevalence in recently pregnant women (25.7%; n = 576) and all women (25.5%; n = 5138) is similar over the age-range 15-44 years. As in high fertility populations, HIV prevalence is higher in pregnant women at young ages and lower at older ages but the crossover point occurs later due to delayed sexual activity. HIV understatement at older ages due to HIV-associated infertility is mitigated by less HIV infection and less frequent ANC attendance in contraceptive users. The local ANC HIV prevalence estimate is lower [21.2%; n = 1215; risk ratio versus pregnant women in the general population, 0.8; 95% confidence interval (CI), 0.7-1.0], possibly because women from more remote areas are included. ANC estimates overstate the relative risk of HIV in more educated women (age-adjusted odds ratio, 1.1; 95% CI, 0.8-1.4 versus 0.7; 95% CI, 0.6-0.9).

CONCLUSIONS

ANC estimates understate female HIV prevalence in this low fertility population but, here, the primary cause is not selection of pregnant women. ANC estimate adjustment procedures that control for contraceptive use and age at first sex are needed.

Risk factors for human immunodeficiency virus infection in Ethiopian children with tuberculosis

BACKGROUND

Separate risk factors for HIV infection and for tuberculosis (TB) are well-studied, but it is unclear whether these risk factors still apply in the new epidemiologic situation of dual infection. This study examines risk factors associated with seropositivity for HIV in Ethiopian children with clinical TB.

METHODS

A prospective, controlled study of children with TB diagnosed in Addis Ababa from December 11, 1995, to January 28, 1997, in which HIV-positive children were compared with HIV-negative children with regard to sociodemographic background, previous medical history and vaccination.

RESULTS

HIV prevalence among children with clinical TB was 11.2%. High educational status of mothers, low age, loss of one or two parents and earlier Calmette-Guérin bacillus (BCG) vaccination of the child were factors independently related to HIV infection.

CONCLUSION

Factors associated with HIV infection among children with clinical TB include higher education of parents, higher income and better living conditions. The HIV epidemic might thus modify traditional risk factors for tuberculosis. It might also decrease the overall effect of BCG vaccination given that BCG did not provide protection in children infected with HIV. An expected increase of dually infected children who are younger, more in need of hospitalization and often lacking one or both parents will put an additional burden on the Ethiopian health care system.

The development of the HIV epidemic in Karonga District, Malawi

OBJECTIVE

To investigate the prevalence and sociodemographic risk factors for HIV infection, during the early stages of the epidemic, in a rural area of northern Malawi.

METHODS

As part of a community-based study of mycobacteria, socioeconomic data and HIV results are available on approximately 30,000 individuals from random population samples in 1981-1984 and 1987-1989 from a rural area of Malawi. These have been analysed to characterize the early stages of the HIV epidemic.

RESULTS

The earliest HIV-positive specimens were collected in 1982. HIV prevalence in individuals aged 15-49 years was 0.1% in the early 1980s and 2.0% in the late 1980s. In the early 1980s, eight out of 11 HIV-positive individuals were new immigrants to the district or had recently returned there. In the late 1980s, immigration and having spent time outside the district continued to be major risk factors for HIV. HIV infection was more common in those with occupations other than subsistence farming, in those with more schooling, and in those in the best housing. The association with schooling was seen at all ages for both men and women.

CONCLUSION

Immigration and travel were important in the repeated introduction and establishment of the HIV epidemic. The association with schooling is similar to that found elsewhere in Africa.

Factors influencing the difference in HIV prevalence between antenatal clinic and general population in sub-Saharan Africa

OBJECTIVE

To compare HIV prevalence in antenatal clinics (ANC) and the general population, and to identify factors determining the differences that were found.

DESIGN

Cross-sectional surveys in the general population and in ANC in three cities.

METHODS

HIV prevalence measured in adults in the community was compared with that measured by sentinel surveillance in ANC in Yaoundé, Cameroon, Kisumu, Kenya, and Ndola, Zambia.

RESULTS

In Yaoundé and Ndola, the HIV prevalence in ANC attenders was lower than that in women in the population overall, and for age groups over 20 years. In Kisumu, the HIV prevalence in ANC attenders was similar to that in women in the population at all ages. The only factors identified that influenced the results were age, marital status, parity, schooling, and contraceptive use. The HIV prevalence in women in ANC was similar to that in the combined male and female population aged 15-40 years in Yaoundé and Ndola, but overestimated it in Kisumu. In Yaoundé and Ndola, the overall HIV prevalence in men was approximated by using the age of the father of the child reported by ANC attenders, but this method overestimated the HIV prevalence in Kisumu, and did not give good age-specific estimates.

CONCLUSION

Few factors influenced the difference in HIV prevalence between ANC and the population, which could aid the development of adjustment procedures to estimate population HIV prevalence. However, the differences between cities were considerable, making standard adjustments difficult. The method of estimating male HIV prevalence should be tested in other sites.

Timing of the HIV-1 subtype C epidemic in Ethiopia based on early virus strains and subsequent virus diversification

OBJECTIVE

To trace the introduction of HIV-1 subtype C into Ethiopia based on virus diversification during the epidemic.

DESIGN

A set of 474 serum samples obtained in Ethiopia in 1982-1985 was tested for HIV-1. HIV-1 env gp120 V3 and gag or pol regions were sequenced and analysed together with sequences from later stages of the epidemic.

RESULTS

None of 98 samples from 1982-1983, one of 193 samples from 1984, and one of 183 samples from 1985 were HIV-1 positive. Phylogenetic analysis of virus sequences from positive samples revealed that they belong to the Ethiopian C, and not the C', cluster. Analysis of 81 Ethiopian C V3 sequences from 1984-1997 revealed that the consensus sequence of the Ethiopian epidemic has been stable over time. Both the 1984 and 1985 V3 sequences, in contrast with three out of 27 (11%) of the 1988 and none out of 51 of the 1992-1997 sequences, had no synonymous substitutions compared to the reconstructed common ancestor of the Ethiopian C viruses. A highly significant correlation between sampling years of the V3 sequences and their synonymous distances to the common ancestor was demonstrated.

CONCLUSIONS

The increasing genetic heterogeneity together with stable consensus sequence of the Ethiopian HIV-1 C population demonstrates that evolution of the virus population is characterized by an unbiased expansion around a stationary consensus. Based on the rate of synonymous diversification of HIV-1 strains within the Ethiopian population, we were able to estimate 1983 (95% confidence interval, 1980-1984) as the year of HIV-1 C introduction into Ethiopia.

Why do young women have a much higher prevalence of HIV than young men? A study in Kisumu, Kenya and Ndola, Zambia

OBJECTIVE

To examine the factors responsible for the disparity in HIV prevalence between young men and women in two urban populations in Africa with high HIV prevalence.

DESIGN

Cross-sectional survey, aiming to include 1000 men and 1000 women aged 15-49 years in Kisumu, Kenya and Ndola, Zambia.

METHODS

Participants were interviewed and tested for HIV and other sexually transmitted infections. Analyses compared the marital and non-marital partnership patterns in young men and women, and estimated the likelihood of having an HIV-infected partner.

RESULTS

Overall, 26% of individuals in Kisumu and 28% in Ndola were HIV-positive. In both sites, HIV prevalence in women was six times that in men among sexually active 1 5-19 year olds, three times that in men among 20-24 year olds, and equal to that in men among 25-49 year olds. Age at sexual debut was similar in men and women, and men had more partners than women. Women married younger than men and marriage was a risk factor for HIV, but the disparity in HIV prevalence was present in both married and unmarried individuals. Women often had older partners, and men rarely had partners much older than themselves. Nevertheless, the estimated prevalence of HIV in the partners of unmarried men aged under 20 was as high as that for unmarried women. HIV prevalence was very high even among women reporting one lifetime partner and few episodes of sexual intercourse.

CONCLUSIONS

Behavioural factors could not fully explain the discrepancy in HIV prevalence between men and women. Despite the tendency for women to have older partners, young men were at least as likely to encounter an HIV-infected partner as young women. It is likely that the greater susceptibility of women to HIV infection is an important factor both in explaining the male-female discrepancy in HIV prevalence and in driving the epidemic. Herpes simplex virus type 2 infection, which is more prevalent in young women than in young men, is probably one of the factors that increases women's susceptibility to HIV infection.

Timing of the introduction into Ethiopia of subcluster C' of HIV type 1 subtype C

Viruses circulating in Ethiopia during the 1990s cluster with main subtype C, but a significant subcluster, C', was noted in multiple analyses. This subcluster of subtype C(C') was in a fifty-fifty equilibrium with the main subtype C (Abebe et al., AIDS Res Hum Retroviruses 2000;16:1909-1914). To analyze genetic diversification within the subcluster of HIV-1 subtype C designated C' in the course of the epidemic in Ethiopia, we analyzed 165 env gp120 V3 sequences obtained between 1988 and 1999. We observed a highly significant positive correlation between sampling years of individual sequences and their synonymous distances to the reconstructed common ancestor of the HIV-1 subtype C' subcluster. The extrapolation of the regression line of synonymous distances back to the date when no synonymous heterogeneity was present among the Ethiopian HIV-1 C' population allowed us to estimate 1982 (95% CI, 1980-1983) as the year of the onset of HIV-1 C' genetic diversification and expansion in Ethiopia. These results are in agreement with retrospective epidemiological and serological data, which demonstrated the absence of an HIV-1 epidemic in the Ethiopian population before the 1980s.

No difference in in vitro susceptibility to HIV type 1 between high-risk HIV-negative Ethiopian commercial sex workers and low-risk control subjects

Host factors such as increased beta-chemokine production, HIV-1 coreceptor expression level, and HIV-1 coreceptor polymorphism have been thought to influence susceptibility to HIV-1 infection. To determine the protective role of these factors in Ethiopians who remained HIV-1 uninfected, despite multiple high-risk sexual exposures, we studied 21 Ethiopian women who had been employed as commercial sex workers (CSWs) for five or more years. The HIV-1-resistant CSWs were compared with low-risk age-matched female controls who had a comparable CD4+ cell percentage and mean fluorescence intensity (MFI). Genetic polymorphism in the CCR5, CCR2b, or SDF-1 genes appeared not to be associated with resistance in the Ethiopian CSWs. Expression levels of CCR5 and CXCR4 on naive, memory, and total CD4+ T cells tended to be higher in the resistant CSWs, while the production of beta-chemokines RANTES, MIP-1alpha, and MIP-1beta by phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMCs) was lower compared with low-risk HIV-1 negative controls. In vitro susceptibility of PHA-stimulated PBMCs to primary, CCR5-restricted, Ethiopian HIV-1 isolates was comparable between resistant CSWs and low-risk controls. In vitro susceptibility was positively correlated to CD4+ cell mean fluorescence intensity and negatively correlated to CCR5 expression levels, suggesting that infection of PBMCs was primarily dependent on expression levels of CD4 and that CCR5 expression, above a certain threshold, did not further increase susceptibility. Our results show that coreceptor polymorphism, coreceptor expression levels, beta-chemokine production, and cellular resistance to in vitro HIV-1 infection are not associated with protection in high-risk HIV-1-negative Ethiopian CSWs.

Factors associated with HIV-1 infection among sex workers of Addis Ababa, Ethiopia

OBJECTIVE

To study the prevalence and risk factors for HIV infection among sex workers of Addis Ababa, Ethiopia.

DESIGN AND METHODS

Cross-sectional survey on socio-demographic characteristics, behaviours, and HIV serological status of sex workers attending two health centres of Addis Ababa.

RESULTS

HIV prevalence among sex workers was 274 of 372 (73.7%). Several factors were significantly associated with an increased risk of being HIV-infected [among others, working in 'shared rooms', high number of clients, use of injectable hormones, and positive Treponema pallidum particle agglutination (TPPA) serology], and others with a decreased risk (being born in Addis Ababa, high level of education, peer education on sex work, condom use, use of oral pill, and use of condoms for contraception). Of interest, sex workers who were using condoms for contraception were, compared with others, more likely to use condoms consistently (65 versus 24%, respectively; P < 0.001), and less likely to be HIV-infected (55 versus 86%, respectively; P < 0.001). In multivariate analysis [log-binomial model, giving estimates of the prevalence ratio (PR)], being born in Addis Ababa (PR = 0.74; 95% confidence interval (CI), 0.61-0.91), using condoms for contraception (PR = 0.73; 95% CI, 0.64-0.85), and a positive TPPA serology (PR = 1.21; 95% CI, 1.09-1.36), remained significantly associated with HIV infection.

CONCLUSIONS

HIV prevalence was remarkably high among sex workers of Addis Ababa. Condom use was higher, and HIV prevalence lower, in sex workers using condoms not only for prevention of HIV and sexually transmitted diseases, but also for contraceptive purpose. This finding is of particular interest for its implications for prevention strategies among sex workers in the developing world.

Identification of a genetic subcluster of HIV type 1 subtype C (C') widespread in Ethiopia

Others and we have previously shown that subtype C is the predominant HIV-1 subtype and the major cause of AIDS in Ethiopia. The present study shows that subtype C in Ethiopia has a genetic subcluster, designated C', has not increased in frequency, or spread geographically, over the period 1988 (%C' = 23/53) to 1996-1997 (%C' = 26/50). There is no association of the HIV-1 subtype C or subcluster C' with geographic location, time of sample collection, or risk group in Ethiopia. Of 105 randomly collected samples representing 7 different towns in Ethiopia, all but 2 (1 subtype A from Addis Ababa, 1997 and 1 subtype D from Dessie, 1996) belong to subtype C.

Sputum concentration improves diagnosis of tuberculosis in a setting with a high prevalence of HIV

Sputum microscopy for acid-fast bacilli (AFB), although relatively insensitive, is still the cornerstone of tuberculosis (TB) diagnosis in the developing world. Its diagnostic value has been eroded owing to the increasing number of HIV-related smear-negative pulmonary TB cases. Concentration of sputum by centrifugation after liquefaction with sodium hypochlorite is a possible means of increasing the sensitivity of direct microscopy. This procedure has been studied recently in developing countries although with conflicting results. The aim of our study, performed in 1996 in Addis Ababa, Ethiopia, was to evaluate the sensitivity of the concentration method in a large cohort of consecutive patients with suspected pulmonary TB. We show that the overall sensitivity increased from 54.2% using conventional direct microscopy to 63.1% after concentration (P < 0x0015). In HIV-positive patients, sensitivity increased from 38.5% before to 50.0% after concentration (P < 0x0034). The significant increase in yield of AFB in HIV-positive patients suggests that this method has a place in routine diagnosis of pulmonary TB in countries with a high prevalence of HIV.

Monitoring the AIDS epidemic using HIV prevalence data among young women attending antenatal clinics: prospects and problems

OBJECTIVE

To assess the potential of antenatal surveillance data on HIV prevalence in young women as an indicator of trends in HIV incidence.

DESIGN

Review of empirical data and discussion of problems encountered with surveillance systems, illustrated using cohort-component projection models.

METHODS

Simple descriptive analyses are presented of prevalence and incidence data, with projection models used to explore aspects of the dynamic relationships between changes in HIV incidence and prevalence in young pregnant women for which empirical data are not yet available. Incidence changes due to change in risk among sexually active, and change in pattern of sexual debut are explored separately, and the resulting prevalence trends in pregnant women under age 25 years, and those expecting their first two births are described.

RESULTS

HIV prevalence levels in young pregnant women categorized by age and by parity have different relationships to recent incidence levels. Age categorized prevalence data provide a reasonable indication of incidence under stable conditions, but may be very misleading if the age pattern of sexual debut changes. Prevalence levels categorized by parity are a reliable guide to incidence in the sexually active, but not necessarily to incidence in the population as a whole.

CONCLUSIONS

Ante-natal surveillance systems should categorize prevalence data by both age and parity to aid in the interpretation of underlying incidence levels.

Seven-year trends in HIV-1 infection rates, and changes in sexual behaviour, among adults in rural Uganda

OBJECTIVE

To assess trends in HIV-1 infection rates and changes in sexual behaviour over 7 years in rural Uganda.

METHODS

An adult cohort followed through eight medical-serological annual surveys since 1989-1990. All consenting participants gave a blood sample and were interviewed on sexual behaviour.

RESULTS

On average, 65% of residents gave a blood sample at each round. Overall HIV-1 prevalence declined from 8.2% at round 1 to 6.9% at round 8 (P = 0.008). Decline was most evident among men aged 20-24 years (11.7 to 3.6%; P < 0.001) and women aged 13-19 (4.4% to 1.4%; P = 0.003) and 20-24 (20.9% to 13.8%; P = 0.003). However, prevalence increased significantly among women aged 25-34 (13.1% to 16.6%; P = 0.04). Although overall incidence declined from 7.7/1000 person-years (PY) in 1990 to 4.6/1000 PY in 1996, neither this nor the age-sex specific rates changed significantly (P > 0.2). Age-standardized death rates for HIV-negative individuals were 6.5/1000 PY in 1990 and 8.2/1000 PY in 1996; corresponding rates for HIV-positive individuals were 129.7 and 102.7/1000 PY, respectively. There were no significant trends in age-adjusted death rates during follow-up for either group. There was evidence of behaviour change towards increase in condom use in males and females, marriage at later age for girls, later sexual debut for boys and a fall in fertility especially among unmarried teenagers.

CONCLUSIONS

This is the first general population cohort study showing overall long-term significant reduction in HIV prevalence and parallel evidence of sexual behaviour change. There are however no significant reductions in either HIV incidence or mortality.

Clinical management and prevention of sexually transmitted diseases: a review focusing on women

This review highlights some of the difficulties inherent in controlling sexually transmitted diseases (STDs) in developing countries--especially amongst women. Considerable efforts have been made to improve the syndromic approach to STD management but the poor performance of the algorithm for managing vaginal discharge limits the effectiveness of this strategy. The facilitating role of the human immunodeficiency virus (HIV) has been the main impetus to STD control rather than reduction of morbidity in women, especially pregnant women and their children. There are no easy solutions--but action on several fronts, with more attention to core groups, men and adolescents is indicated.

Country-specific estimates and models of HIV and AIDS: methods and limitations

OBJECTIVE

This paper presents the methods used to calculate the end of 1997 country-specific estimates of HIV and AIDS produced by the UNAIDS/WHO Working Group on Global HIV/AIDS and STD Surveillance. The objective of this exercise was to improve estimates on HIV/AIDS by using country-specific models of HIV/AIDS epidemics. The paper describes and discusses the processes and obstacles that were encountered in this multi-partner collaboration including national and international experts.

METHODS

The 1997 estimates required two basic steps. First, point prevalence estimates for 1994 and 1997 were carried out and the starting year of the epidemic was determined for each country. The procedures used to calculate the estimates of prevalence differed according to the assumed type of the epidemic and the available data. The second step involved using these estimates of prevalence over time and the starting date of the epidemic to determine the epidemic curve that best described the spread of HIV in each particular country. A simple epidemiological program (EPIMODEL) was used for the calculation of estimates on incidence and mortality from this epidemic curve.

RESULTS

Regional models that were used in previous estimation exercises were not able to capture the diversity of HIV epidemics between countries and regions. The result of this first country-specific estimation process yielded higher estimates of HIV infection than previously thought likely, with over 30 million people estimated to be living with HIV/AIDS. The application of survival times that are specific to countries and regions also resulted in higher estimates of mortality, which more accurately describe the impact of the epidemics. At the end of 1997, it was estimated that 11.7 million people worldwide had died as a result of HIV/AIDS since the beginning of the epidemic.

CONCLUSION

This exercise is an important step in improving understanding of the spread of HIV in different parts of the world. There are, however, shortcomings in the current systems of monitoring the epidemic. Improvements in HIV surveillance systems are needed in many parts of the world. In addition, further research is needed to understand fully the effects of the fertility reduction as a result of HIV, differing sex ratios in HIV infection and other factors influencing the course and measurement of the epidemic.

HIV-1 subtype C syncytium- and non-syncytium-inducing phenotypes and coreceptor usage among Ethiopian patients with AIDS

OBJECTIVE

To assess syncytium-inducing (SI) and non-syncytium-inducing (NSI) frequencies, coreceptor usage and gp120 V3 sequences of HIV-1 isolates from Ethiopian AIDS patients.

PATIENTS

Cross-sectional study on 48 hospitalized AIDS patients (CD4 T cells < 200 x 10(6) cell/l) with stage III or IV of the WHO staging system for HIV-1 infection and disease.

METHODS

Peripheral blood mononuclear cells (PBMC) from all 48 patients were tested by MT-2 assay to determine SI/NSI phenotypes. Lymphocyte subsets were enumerated using Coulter counting and FACScan analysis. Viral load determination used a nucleic acid sequence-based amplification assay (NASBA). Coreceptor usage of HIV-1 biological clones was measured using U87 CD4/chemokine receptor transfectants and phytohemagglutinin-stimulated PBMC of healthy donors with wild-type CCR5 and homozygous mutation CCR5delta32 (a 32 base-pair deletion in CCR5). Reverse transcriptase polymerase chain reaction sequencing was performed on the third variable region (V3) of the HIV-1 gene gp120. Sequence alignments were done manually; phylogenetic analyses used PHYLIP software packages.

RESULTS

SI viruses were detected for 3/48 (6%) AIDS patients only. Lower mean absolute CD4 counts were determined in patients with SI virus compared with NSI (P = 0.04), but no differences in viral load were observed. All patients were found to be infected with HIV-1 subtype C, based on V3 sequencing. NSI biological clones used CCR5 as coreceptor; SI biological clones used CXCR4 and/or CCR5 and/or CCR3.

CONCLUSIONS

Ethiopian patients with HIV-1 C-subtype AIDS harbour a remarkably low frequency of SI phenotype viruses. Coreceptor usage of these viruses correlates with their biological phenotypes.

Spread of HIV infection in a rural area of Tanzania

OBJECTIVE

To assess the spread of HIV into rural areas.

METHODS

Since 1994 a demographic surveillance system (with 5-monthly rounds) and open adult cohort study have been established in a rural ward in Tanzania. Two sero-surveys of all resident adults aged 15-44 and 15-46 years were conducted in 1994 1995 and 1996-1997 respectively. Qualitative data were collected on mobility, bars and commercial sex.

RESULTS

Attendance of the two rounds of survey was 5820 (78%) and 6413 (80%) in 1994/1995 and 1996/1997 respectively. HIV prevalence increased from 5.8% to 6.6%. HIV incidence was 0.73 and 0.84 per 100 person years among men and women respectively. HIV incidence under the age of 20 years was low among both sexes. Striking differences in HIV prevalence and incidence were observed within the small geographic area studied: HIV prevalence in the trading center was twice that in the area surrounding the trading center (within 2 km) and three to four times that in the rural villages (within 8 km of the trading center). Aggregate level data showed significant differences between the trading center and nearby rural villages in terms of sexual behavior, commercial sex workers, mobility of the population, and alcohol use.

CONCLUSION

This study documents the existence of very substantial HIV prevalence and incidence differences within a small geographic rural area. The rapid decrease in HIV prevalence within a small rural area emphasizes the importance of concentrating HIV prevention efforts on high transmission areas, such as trading centers, especially in resource-poor settings. Furthermore, this has considerable implications for monitoring the spread of HIV through sentinel sites, as such sites are typically located in high transmission areas.

Sexual behaviours, perception of risk of HIV infection, and factors associated with attending HIV post-test counselling in Ethiopia

OBJECTIVES

To describe sexual behaviours, perception of risk of HIV infection, and factors associated with attending HIV post-test counselling (PTC) among Ethiopian adults.

METHODS

Data on socio-demographic characteristics, knowledge of HIV infection, sexual history, medical examination, and HIV and syphilis serological status were compared, through uni- and multivariate analysis, in relation to attending PTC within 60 days of HIV testing.

RESULTS

Between February 1997 and June 1998, 751 factory workers were enrolled in a cohort study of HIV infection progression. Despite reporting high-risk sexual behaviours, mainly for males (64% of males and 6% of females had more than five sexual partners in their lifetime, 16% of males and 2% of females reported having had recent casual partners), and knowing that HIV is commonly transmitted heterosexually in Ethiopia (97% of answers being correct, both genders combined), only 17% of males and 2% of females acknowledged having had activities which had put them at risk of HIV infection. HIV prevalence was 12%, and did not differ by gender. Of all study participants, 327 (43.5%) returned for PTC within 60 days of HIV testing. PTC attendance did not differ by age, gender, or HIV serological status. Factors independently associated with PTC attendance in males were: good knowledge of HIV infection, [odds ratio (OR) = 1.661, belief that medical follow-up improves the course of HIV infection (OR = 2.02), history of genital symptoms (OR = 2.83), positive syphilis serology (OR = 2.62), recent weight loss (OR = 1.89), and, with a negative association, being a manual worker (OR = 0.40), and history of recent casual sexual relationships (OR = 0.35). In women, belief that HIV/AIDS can be cured (OR = 3.16), never having been married (OR = 5.02), having five or less children (OR = 2.16), having been raped (OR = 3.42), and having used health facilities in the past year (OR = 1.73) were all positively and independently associated with PTC attendance.

CONCLUSION

Study participants reported high-risk sexual behaviours, yet had a low perception of individual risk. Men attended for PTC because of their knowledge of HIV infection, their past sexual history or their current health status. Women attended for PTC because of their plans for the future, marriage and/or children, rather than their past sexual exposure. Only in cases of rape were they willing to learn of their HIV status.