Female sex workers population size estimation in Rwanda using a three-source capture-recapture method.

Establishing accurate population size estimates (PSE) is important for prioritising and planning provision of services. Multiple source capture-recapture sampling method increases PSE accuracy and reliability. In August 2018, the three-source capture-recapture (3S-CRC) method was employed with a stringent assumption of sample independence to estimate the number of female sex workers (FSW) in Rwanda. Using Rwanda 2017 FSW hotspots mapping data, street and venue-based FSW were sampled at the sector level of each province and tagged with two unique gifts. Each capture was completed within one week to minimise FSW migration between provinces and recall bias. The three captures had 1042, 1204 and 1488 FSW. There were 111 FSW recaptured between captures 1 and 2; 237 between captures 2 and 3; 203 between captures 1 and 3 and 46 captured in all three. The PSE for street and venue-based FSW in Rwanda lies within 95% credible set: 8328-22 806 with corresponding median of 13 716 FSW. The 3S-CRC technique was low-cost and relatively easy to use for PSE in hard-to-reach populations. This estimate provides the basis for determining the denominators to assess HIV programme performance towards FSW and epidemic control and warrants further PSE for home- and cyber-based FSW in Rwanda.

Survival by AIDS defining condition in rural Uganda.

OBJECTIVES: To report the initial AIDS defining conditions, CD4 lymphocyte counts around the time of AIDS diagnosis, and survival by AIDS defining condition in a population based cohort in rural Uganda. METHODS: Participants in an HIV natural history cohort in rural Uganda were reviewed every 3 months at routine visits and at other times when they were ill. The date and nature of the first AIDS defining condition in participants developing AIDS during follow up between the start of the cohort in 1990 and the end of 1998 were noted. The CD4 count at, or within, 3 months of this time was recorded for those participants who developed AIDS (WHO stage 4) after 1993. RESULTS: The median survival from developing AIDS to death was 9.3 months and the median CD4 lymphocyte count around the time of developing AIDS was 150 cells x 10(6)/l. The most frequent AIDS defining conditions were wasting syndrome, oesophageal candidiasis, and mucocutaneous herpes simplex virus infection (HSV) for more than 1 month. The median survival with wasting syndrome, Kaposi's sarcoma, and oesophageal candidiasis was less than 3.5 months; however, survival with cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis was greater than 20 months. There was little relation between CD4 count around the time of development of the AIDS defining condition and the median survival with that condition. CONCLUSIONS: The survival for most AIDS defining conditions was generally shorter and the median CD4 lymphocyte count higher than studies reported from developed countries. However, the conditions with the longest survival (cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis) had a similar survival to that in developed countries and these conditions have a high background level in this population.

Case-control study of risk factors for incident HIV infection in rural Uganda.

OBJECTIVE: To identify risk factors associated with HIV incidence in a rural Ugandan population. DESIGN: Case-control study. METHODS: Men and women who seroconverted between 1990 and 1997 (cases) and seronegative subjects (controls) were drawn from a general population cohort of approximately 5000 adults in rural, southwestern Uganda. Information on risk factors was ascertained through a detailed interview and physical examination by clinicians who were blind to the study subjects' HIV status. All patients were interviewed within 2 years of their estimated date of seroconversion. RESULTS: Data were available on 130 men (37 cases, 93 controls) and 133 women (46 cases, 87 controls). There was a significantly higher risk of infection in men (odds ratio [OR], 6.51; 95% confidence interval [CI], 1.06-39.84) and women (OR, 4.75; 95% CI, 1.26-17.9) who were unmarried and in a steady relationship, and in men who were divorced, separated, or widowed (OR, 4.33; 95% CI, 1.32-14.25) compared with those who were married. There was a significantly higher risk of HIV infection in men (OR, 3.78; 95% CI, 1.20-11.93) and women (OR, 20.78; 95% CI, 2.94-141.2) who reported > or =5 lifetime sexual partners compared with those who reported at most 1 partner. For men, there was an increased risk of infection associated with receiving increasing numbers of injections in the 6 months prior to interview (p < .001 for trend). Women reporting sex against their will in the year prior to interview were at higher risk of infection (OR, 7.84; 95% CI, 1.29-47.86; p = .020). CONCLUSIONS: The strongest risk factor for HIV incidence in this rural Ugandan population is lifetime sexual partners. The increased risks found for women reporting coercive sex and men reporting injections require further investigation.

Rates of HIV-1 transmission within marriage in rural Uganda in relation to the HIV sero-status of the partners.

OBJECTIVE: To assess the efficacy of transmission of HIV-1 within married couples in rural Uganda according to the sero-status of the partners. DESIGN: Estimation of HIV incidence rates for 2200 adults in a population cohort followed for 7 years comparing male-to-female with female-to-male transmission and sero-discordant with concordant sero-negative couples. METHODS: Each year, adults (over 12 years of age) resident in the study area were linked to their spouses if also censused as resident. The HIV sero-status was determined annually. RESULTS: At baseline 7% of married adults were in sero-discordant marriages and in half of these the man was HIV-positive. Among those with HIV-positive spouses, the age-adjusted HIV incidence in women was twice that of men (rate ratio (RR) = 2.2 95% confidence interval (CI) 0.9-5.4) whereas, among those with HIV-negative spouses, the incidence in women was less than half that of men (RR = 0.4, 95% CI 0.2-0.8). The age-adjusted incidence among women with HIV-positive spouses was 105.8 times (95% CI 33.6-332.7) that of women with HIV-negative spouses, the equivalent ratio for men being 11.6 (95% CI 5.8-23.4). CONCLUSION: Men are twice as likely as women to bring HIV infection into a marriage, presumably through extra-marital sexual behaviour. Within sero-discordant marriages women become infected twice as fast as men, probably because of increased biological susceptibility. Married adults, particularly women, with HIV-positive spouses are at very high risk of HIV infection. Married couples in this population should be encouraged to attend for HIV counselling together so that sero-discordant couples can be identified and advised accordingly.

The prognostic value of the World Health Organisation staging system for HIV infection and disease in rural Uganda.

OBJECTIVE: To assess whether the WHO staging classification for HIV provides prognostically valuable and applicable information in rural Uganda. PATIENTS AND STUDY DESIGN: Data were obtained from a population-based cohort of 232 HIV-infected individuals. METHODS: Clinical information was obtained using a detailed questionnaire and ascertained by physical examination. Participants were seen routinely every 3 months and when they were sick. A computer algorithm based on clinical history, examination and laboratory findings was used to stage HIV-positive participants at each routine visit. Kaplan-Meier survival estimates and the Cox proportional hazard model were used to assess the prognostic strength of the clinical and laboratory categories of the system. RESULTS: An attendance rate of 81% and 799 person-years of follow-up were achieved. Survival probability estimates at 6 years from being seen in clinical stages 1, 2, 3 and 4 were 63, 46, 24 and 6% respectively. When staging was revised to incorporate lymphocyte categories, the survival probabilities were 73, 62, 39 and 6% respectively. Unexplained prolonged fever and severe bacterial infection had survival probabilities closer to stage 2 conditions, mucocutaneous herpes simplex virus infection for more than 1 month and crytosporidiosis with diarrhoea for more than 1 month closer to stage 3 and oral candidiasis closer to stage 4 conditions. CONCLUSIONS: Even without the laboratory markers, the clinical category of the WHO staging system is useful for predicting survival in individuals with HIV disease. This is important for areas with limited access to laboratory markers. A simple rearrangement of a few clinical conditions could improve the prognostic significance of the WHO system.

HIV-1 disease progression and AIDS-defining disorders in rural Uganda.

BACKGROUND: The majority of people infected with HIV-1 live in Africa, yet little is known about the natural history of the disease in that continent. We studied survival times, disease progression, and AIDS-defining disorders, according to the proposed WHO staging system, in a population-based, rural cohort in Uganda. METHODS: In 1990 we recruited a random sample of people already infected with HIV-1 (as prevalent cases) detected during the initial survey round of a general-population study to form a natural-history cohort. Individuals from the general-population cohort who seroconverted between 1990 and 1995 (incident cases) were also invited to enroll. Participants were seen routinely every 3 months and when they were III. FINDINGS: By the end of 1995, 93 prevalent cases and 86 incident cases had been enrolled. Four patients in the prevalent group were in stage 4 (AIDS) at the initial visit. During the next 5 years, 37 prevalent cases progressed to AIDS. Seven incident cases progressed to AIDS and the cumulative progression to AIDS at 1, 3, and 5 years after seroconversion was 2%, 6%, and 22%, respectively. The cumulative probability of AIDS at 4 years from entering stages 1, 2, and 3 was 11%, 33%, and 58%, respectively. There were 47 deaths among prevalent cases and seven among incident cases during follow-up. The cumulative mortality 4 years after patients entered stages 1, 2, 3, and 4 was 9%, 33%, 56%, and 86%, respectively. The median survival after the onset of AIDS was 9.3 months. INTERPRETATION: Our results are important for the setting of priorities and rationalisation of treatment availability in countries with poor resources. We found that progression rates to AIDS are similar to those in developed countries for homosexual cohorts and greater than for cohorts infected by other modes of transmission. However, we have found that the rates of all-cause mortality are much higher and the progression times to death are shorter than in developed countries.

PIP: The authors studied AIDS-defining disorders, disease progression, and survival times in cohorts of HIV-infected people in a rural region of Uganda. A random sample of people already infected with HIV-1 was recruited in 1990. The subjects had been detected during the initial survey round of a general-population study to form a natural-history cohort. Individuals from the general-population cohort who seroconverted between 1990 and 1995 were also invited to enroll in the study. Participants were seen routinely every 3 months and when they were ill. By the end of 1995, 93 prevalent cases and 86 incident cases had been enrolled. Four patients in the prevalent group were in World Health Organization-defined stage 4 HIV disease, AIDS, at the initial visit. Over the next 5 years, 37 prevalent cases progressed to AIDS. Seven incident cases progressed to AIDS and the cumulative progression to AIDS at 1, 3, and 5 years after seroconversion was 2%, 6%, and 22%, respectively. The cumulative probability of AIDS at 4 years from entering stages 1, 2, and 3 was 11%, 33%, and 58%, respectively. There were 47 deaths among prevalent cases and seven among incident cases during follow-up. The cumulative mortality 4 years after patients entered stages 1, 2, 3, and 4 was 9%, 33%, 56%, and 86%, respectively. The median survival duration after the onset of AIDS was 9.3 months.

An HIV-1 natural history cohort and survival times in rural Uganda.

OBJECTIVE: To describe a population-based rural cohort of HIV-1-seropositive and seronegative individuals established in 1990 in south-west Uganda, and determine survival times in the cohort. DESIGN: Prospective cohort study. METHODS: Participants were recruited from a large population study, and invited to attend a clinic every 3 months. They were seen by clinicians who administered detailed medical questionnaires and undertook a physical examination. RESULTS: By the end of 1995, 390 (79%) of the 491 people asked to enrol in the natural history cohort (NHC) had done so. Ninety-three were prevalent cases of HIV infection detected during the initial survey round of the general population cohort in 1989/1990, 66 were subsequent incident cases, 177 were age-matched HIV-negative controls and 54 were HIV-negative spouses of HIV-positive individuals. Twenty participants seroconverted in the NHC. The age-standardized mortality rates per 1000 person-years for the prevalent, incident, and negative cases were 156.5 [95% confidence interval (CI), 115.8-211.4], 35.0 (95% CI, 16.4 75.0) and 13.5 (95% CI, 7.3-25.1), respectively. The median survival time from enrolment to death for the prevalent cases was 4.5 years (95% CI, 3.5- > 5.2); > 5.4 years from seroconversion for the incident cases; and > 5.2 years from enrolment for the HIV-negative cases. The 5-year cumulative survival for prevalents, incidents and HIV-negative participants was 46%, 83% and 94%, respectively. CONCLUSIONS: We have described an NHC of HIV-positive and HIV-negative participants which is representative of the general population. The NHC was established over 5 years ago; it is continuing and we are maintaining good compliance rates. Survival probabilities in the cohort were lower than most other reported studies.

PIP: To enhance understanding of the natural history of HIV-1 infection among the general population in Africa, a population-based cohort of HIV-prevalent (n = 93) and HIV-incident (n = 66) cases, HIV-negative controls (n = 177), and seronegative partners of HIV-positive cases (n = 54) was recruited in rural southwest Uganda. Between 1990 and 1995, 1353 people-years (PY) of observation were achieved. There were 20 seroconversions during this period. The median duration from enrollment to seroconversion were 25 months for negative controls and 6 months for negative discordants. Of the 64 deaths over the 5-year study period, 54 involved HIV-infected subjects. The age-standardized mortality rates for the prevalent, incident, and negatives per 1000 PY of observation were 156.5 (95% confidence interval [CI], 115.8-211.4), 35.0 (95% CI, 17.4-75.0), and 13.5 (95% CI, 7.3-25.1), respectively. There were no significant differences in the gender-specific mortality rates per 1000 PY in males (48.9) and females (45.7). The median ages at death of prevalent, incident, and negative participants were 33, 53, and 53 years, respectively. The median survival times from enrollment to death were 4.5 years for prevalent cases, over 5.4 years for incident cases, and over 5.2 years for HIV-negative cases. At 5 years, the cumulative survival probabilities for prevalent, incident, and negative cases were 46%, 83%, and 94%, respectively, considerably lower than those reported in other studies. Follow-up of the cohort will continue, and future papers will address the clinical manifestations and other parameters of disease progression.

HIV-1 infection in a Ugandan town on the trans-African highway: prevalence and risk factors.

All adult residents (aged 13 years or more) of 154 randomly selected households in 3 urban and one semi-rural ward of a town in South West Uganda on the trans-African highway were invited to participate in a socio-demographic, behavioural and medical survey. An unambiguous HIV-1 serostatus was obtained for 389 (80%) adults. The overall sero-prevalence rate was 40.4%; all age groups except males aged 13-19 years had infection rates in excess of 20%. Rates above 50% were found in females aged 20-34 years and males aged 35-44 years. For females seropositivity rates increased steeply with increasing numbers of lifetime sexual partners up to a maximum of 3; in contrast, for males rates continued to increase with increasing numbers of partners. The risk of infection amongst those with only one reported partner was 17%. A high proportion of males (14%) and females (18%) reported a history of genital ulcer disease within the previous 6 months; on examination genital lesions were observed in 12% of all participants. Interventions with a single focus are unlikely to have much impact in such a situation and a strategy is suggested which includes 3 components, namely improved STD control, a reduction in partner change and an increase in condom utilization.

PIP: In mid-1991, in a Ugandan town on the trans-African highway, interviews were conducted with and blood specimens taken from 389 persons aged 13 to more than 45 years from 154 households to assess the prevalence of HIV-1 infection and to identify its risk factors. The overall HIV-1 prevalence rate stood at 40.4% (35.6% for men and 43.7% for women). The highest HIV-1 prevalence rates were among men aged 35-44 (56.7%) and women aged 20-24 and aged 25-34 (52.9% and 50.6%, respectively). The urban rate was higher than the semi-rural rate (44.1% vs. 25.6%; p 0.005). 65% of all households had at least one HIV-1 seropositive adult. Single adults had a lower HIV-1 seroprevalence rate than ever married adults (e.g., among men, 10.3% vs. 30.8-62.5%) (relative risk [RR] = 2.8; p 0.005). The Baganda ethnic group had the lowest rate, while the Rwandese group had the highest rate (35.8% vs. 59.2%; RR = 1.4). Education did not affect the prevalence rate. Employed persons were more likely to have HIV-1 infection than the unemployed (44.4% vs. 32.6%; p 0.05). The occupations with the highest HIV-1 infection rates were business person (56.2%) and bar attendant (50%). History of blood transfusion did not appear to be a risk factor for HIV-1 infection (28% vs. 41.3% for no history). 33 HIV-1 seropositive adults had never had sexual intercourse. Men were more likely to have had multiple sex partners than women (e.g., having at least 10 lifetime partners, 61% vs. 11%). Seropositivity rates increased greatly with rising numbers of lifetime sexual partners to a maximum of 3 for females, but it continued to rise for men. It increased for men as the number of contacts in the last month increased (p = 0.05 for trend). 14% of men and 18% of women had a genital ulcer disease in the last 6 months. These findings suggest a need for a three-pronged AIDS prevention strategy: improved sexually transmitted disease control, a reduction in partner change, and an increase in condom use.

Human immunodeficiency virus (HIV-1) seropositivity among children in a rural population of south-west Uganda: probable routes of exposure.

Serological studies on 7796 rural Ugandans showed 377 (4.8%) were HIV-1 antibody-positive, of whom 343 (8.2%) were adults, ten (0.4%) 5-12-year-olds and 24 (1.7%) under 5 years of age. Serological tests done on 18 mothers of the under-5s showed 17 to be HIV-1-positive. One mother was persistently negative. Her child had a history of multiple injections. Structured interviews with parents or guardians of the ten HIV-1-seropositive children aged 5-12 years to determine possible sources of exposure revealed that six were vertically infected and that blood transfusion, injections and sexual exposure each accounted for one case. It was not possible to identify a source of exposure in one instance. There was no evidence that casual household contact or scarifications played a role in the transmission of HIV-1 in children in this population. Our data show that in this rural population HIV-1 seropositivity in children is mainly associated with seropositivity in the mothers and that HIV-1 infection in children aged between 5 and 12 years is rare.

Risk factors for HIV-1 infection in adults in a rural Ugandan community: a case-control study.

OBJECTIVE: To study in depth sexual history and sexual behaviour variables as risk factors for HIV-1 infection in a rural Ugandan population. METHODS: Following a socioeconomic and serological survey of a rural population in Masaka District, south-west Uganda, 233 randomly selected HIV-1-positive cases and 233 negative controls matched on age and village of residence, were invited in October 1990 to participate in a case-control study. A total of 132 cases and 161 controls attended for in-depth investigation including an interview about sexual behaviour. RESULTS: The factor most strongly associated with increased risk of infection was a greater number of lifetime sexual partners, with odds ratios (OR) of 2.1 and 4.9 for those reporting 4-10 and 11 or more partners, respectively, compared with those reporting less than four partners. Having only one sexual partner did not provide complete protection, a total of seven (one male, six female) subjects reporting only one sexual partner were HIV-1-positive. Other significant factors were a history of genital ulcers [OR, 2.9; 95% confidence intervals (CI), 1.0-9.1) and not being a Muslim (OR, 5.4; 95% CI, 1.8-16.5) suggesting a possible protective effect of circumcision. There was a suggestion that those who married within the last 7 years (OR, 2.4; 95% CI, 0.9-6.1) and men exposed to menstrual blood (OR, 5.7; 95% CI, 0.7-49.8) were at an increased risk of HIV-1 infection. CONCLUSIONS: These results confirm the predominant role of sexual behaviour in the HIV-1 epidemic. Of particular concern is the observation of HIV-1 infection among those reporting only one partner. Where HIV-1 infection is widely distributed in the general population, risk reduction strategies should, in addition to the promotion of partner reduction, place strong emphasis on safe-sex techniques.

Risk factors for HIV-1 infection in adults in a rural Ugandan community: a population study.

OBJECTIVE: To determine sociodemographic risk factors associated with HIV-1 infection in a rural Ugandan population. DESIGN: A population-based survey. METHODS: All adult residents (aged > or = 13 years) in a cluster of 15 neighbouring villages of the Masaka District of south-west Uganda were invited to participate in a sociodemographic and serological survey. Questions relating to sexual behaviour were asked separately in an accompanying case-control study. Socioeconomic data and an unambiguous HIV-1 serostatus were obtained by house-to-house survey for 3809 (72%) of the adult population. The association between serostatus and the following variables were analysed: age, sex, marital status, tribe, religion, education, occupational group, place and frequency of travel and recent history of sexually transmitted disease. RESULTS: Women aged 13-21 years were at a much higher risk than men of the same age [odds ratio (OR), 8.6; 95% confidence interval (CI), 3.0-24.5]. Married people aged < 25 years were twice as likely to be infected as those who were not currently married (OR, 2.3; 95% CI, 1.5-3.7). In contrast, in those aged > or = 25 years, women were at a lower risk than men (OR, 0.72; 95% CI, 0.52-0.98) as were those who were currently married compared with those who were not (OR, 0.47; 95% CI, 0.34-0.64). In both age groups those with a history of a recent genital ulcer were approximately three times more likely to be infected. Muslims had lower risks than non-Muslims (OR, 0.58 for both age groups). CONCLUSIONS: The people most at risk of HIV-1 infection in this rural Ugandan population are young married women who had, presumably, commenced sexual activity recently.