Anita Sandström

Prevalence of HIV-1 infection in the Kagera region of Tanzania: a population-based study.

A population-based survey was carried out in the Kagera region of the United Republic of Tanzania in 1987 to determine the magnitude of HIV-1 infection and to study associated risk factors. The region was divided into one urban and three rural zones. A multistage cluster sampling technique was adopted. Antibodies to HIV-1 were determined by enzyme-linked immunosorbent assay and confirmed by Western blot analysis. A total of 2,475 adults (aged 15-54 years) and 1,961 children (aged 0-14 years) was studied. The overall prevalence of HIV-1 infection among adults was 9.6%, with a higher prevalence in the urban zone (24.2%) than in the three rural zones (10.0, 4.5 and 0.4%, respectively). The corresponding figures for children were 1.3% overall: 3.9% in the urban area and for the rural areas 1.2, 0.8 and 0.0%, respectively. The age-specific seroprevalence for adults was highest in the age group 25-34 years. The age-standardized sex-specific prevalence was higher among women than men in the urban zone, while it was the same in the rural zones. Change of sexual partners among adults was associated with an increased risk of HIV-1 seropositivity. Travelling outside the region but within the country was also found to be associated with increased risk of HIV-1 infection but only in the rural population.

Declining Hiv-2 prevalence and incidence among men in a community study from Guinea-bissau

Objective:To assess the present level of HIV-2 infection in an adult population in Bissau and to evaluate sex and age-specific changes in HIV-2 prevalence and incidence between 1987 and 1996. Design and methods:Sex and age-specific changes in HIV-2 prevalence were evaluated comparing a survey from 1987 in a sample of 100 houses with a survey performed in 1996 in an independent sample of 212 houses from the same study area. HIV-2 incidence rates were examined in an adult population (age ≥ 15 years) from 100 randomly selected houses followed with four consecutive HIV serosurveys from 1987 to 1996. Results:The HIV-2 prevalence in 1996 was 6.8% (men, 4.7%; women, 8.4%). Compared with the 1987 survey there was a significant decrease in prevalence among men [age-adjusted relative risk (RR), 0.50; 95% confidence interval (CI), 0.31–0.83], whereas it remained unchanged in women (RR, 1.00; 95% CI, 0.67–1.48). The male-to-female RR decreased from 0.99 (95% CI, 0.61–1.61) in 1987 to 0.51 (95% CI, 0.34–0.76) in 1996. The overall annual incidence rate was 0.54 per 100 person-years of observation (PYO), being higher in women (0.72 per 100 PYO) than in men (0.31 per 100 PYO). With the observation time divided into an early and a late period, there was a decrease in incidence with time among men (0.66 to 0.00 per 100 PYO), but no major change among women (0.59 to 0.85 per 100 PYO). The two trends differed significantly (P = 0.03). We observed a higher annual incidence rate amongst older women aged > 44 years (1.77 per 100 PYO) than among younger women (0.55 per 100 PYO; P = 0.05). Conclusion:There are no signs of an epidemic spread of HIV-2 in Bissau even though the HIV-1 prevalence is increasing rapidly. A significant reduction in the male HIV-2 prevalence and incidence rates has resulted in a major shift in the pattern of spread of HIV-2, from being equally distributed to being predominantly a female infection. Currently, older women in particular seem to have a high risk of getting infected.

Monitoring of HIV-1 infection prevalence and trends in the general population using pregnant women as a sentinel population: 9 years experience from the Kagera region of Tanzania.

Summary: In the Kagera region of Tanzania, a population‐based study was initiated in 1987 followed by the establishment of antenatal‐clinic‐based sentinel surveillance system in the town of Bukoba in 1990. Repeat studies in both populations in Bukoba in 1993 and 1996 made it possible to study the dynamics of HIV infection prevalence and incidence in the area. This study aims at comparing the findings from this sentinel surveillance system with those of cross‐sectional studies in the general population to assess its validity in estimating HIV prevalence and their trends in the general population. A multistage cluster sampling technique was used in the population‐based studies whereas the antenatal‐clinic‐based population was obtained by consecutively recruiting antenatal care attenders coming for the first time during a given pregnancy. Antibodies against HIV infection were tested using two independent enzyme‐linked immunosorbent assay (ELISA) antibody detection tests. Unlinked anonymous testing strategy was adopted for the sentinel population. Age‐adjusted prevalence among antenatal care attenders decreased from 22.4% (95% confidence interval [CI], 20.6‐25.2) in 1990 to 16.1% (95% CI, 15.9‐18.8) in 1993 and further to 13.7% (95% CI, 11.8‐14.3) in 1996. These results closely resemble those of the general population of adult women in the clinics catchment area (the town of Bukoba) where the ageadjusted prevalence of 29.1% (95% CI, 24.4‐34.6) in 1987 showed a decrease in the studies in 1993 18.7% (95% CI, 15.1‐23.0) and in 1996 14.9% (95% CI, 12.0‐17.1). The study indicates that general population trend estimates can be generated using sentinel surveillance data based on pregnant women visiting an antenatal clinic for the first time during a given pregnancy. The benefits of using this group outweigh its limitations that are brought about by possible selection bias. Continued surveillance of the epidemic based on antenatal care patients as a sentinel population is therefore recommended.

Prevalences of HTLV-1 infection and associated risk determinants in an urban population in Guinea-Bissau, West Africa.

Objective: To assess the prevalence and modes of transmission of HTLV‐1 infection in an adult population in Bissau, and to evaluate possible interactions between the pattern of spread of HTLV‐1 and HIV‐1/HIV‐2. Design and Methods: Univariate and multivariate analyses were used to evaluate gender‐ and age‐specific HTLV‐1 prevalences as well as associated risk determinants in an adult population based on a serosurvey comprising 2127 individuals from 304 randomly selected houses in Bissau. Results: Using stringent Western blot criteria, the overall seroprevalence of HTLV‐1 was 3.6%, 2.2% among men and 4.7% among women, respectively. One individual was seropositive to HTLV‐2. The prevalence of HTLV‐1, which increased with age in both genders, however more markedly among women, was >4 times higher (9.4%) among older individuals (>44 years of age) than among younger individuals (2.4%). Blood transfusion and HIV‐2 seropositivity were independently associated with HTLV‐1 seropositivity in men. Among women, both HIV‐2 seropositivity and HIV‐1 seropositivity were significant risk determinants. Having had sexual partners was associated with a fivefold increased risk among women but did not reach significance. Conclusion: The adult population of Guinea‐Bissau has a higher prevalence of HTLV‐1 than reported from most other countries in West Africa. The gender‐ and age‐specific pattern of spread of HTLV‐1 closely resembles that observed for HIV‐2, another retrovirus prevalent to the region. The close correlation between HTLV‐1 and HIV‐2 most likely reflects the shared risk factors related to sexual behavior. The implication of the high percentage of double infections in this population needs to be determined.

Decline in the prevalence of HIV-1 infection in young women in the Kagera region of Tanzania.

In northwestern Tanzania, a population-based survey of HIV-1 infection in the Kagera region in 1987 demonstrated a high prevalence (24.2%) in adults of Bukoba town, whereas it was lower (10.0%) in the surrounding rural district of Bukoba. In 1993 and 1996, population-based cross-sectional studies were carried out in urban and rural Bukoba districts, respectively, to monitor the time trend in the prevalence of HIV-1 infection in the region. In both studies, a multistage cluster sampling technique was adopted in selecting study individuals. Consenting individuals between 15 and 54 years of age were interviewed using a structured questionnaire. Following individual counseling, blood samples were drawn and tested for HIV infection using enzyme-linked immunosorbent assay (ELISA) antibody detection tests. The overall age-adjusted HIV-1 seroprevalence in urban Bukoba decreased from 24.2% (134 of 553) in 1987 to 18.3% (118 of 653) in 1993 (p = .008). The age-adjusted gender-specific prevalence declined significantly in women, from 29.1% (95 of 325) to 18.7% (74 of 395; p = .0009). Except for men > or = 35 years of age, whose prevalence appeared to have an upward trend between the two studies, all other age groups in both genders had a downward trend; this finding was most significant in women between 15 and 24 years of age (from 27.6% to 11.2%; p = .0004). For the rural population, the overall prevalence decreased from 10.0% (54 of 538) in 1987 to 6.8% (118 of 1728) in 1996 (p = .01). Except for rural women between 15 and 24 years of age whose prevalence decreased from 9.7% (12 of 124) to 3.1% (12 of 383; p = .002), other age groups in the rural populations showed no change in prevalence. Ongoing interventions in this area leading to behavioral change may have contributed to this observation. An incidence study is under way to confirm this observation and to investigate the factors that are responsible for the decline in the HIV-1 prevalence.

Protection from cholera by adding lime juice to food – results from community and laboratory studies in Guinea‐Bissau, West Africa

Summary Epidemiological studies have shown that food plays an important role in the transmission of Vibrio cholerae, and different foods have been incriminated in many epidemic outbreaks of cholera. Storing contaminated meals at ambient temperatures allows growth of V. cholerae. Some ingredients such as lime juice may inhibit the survival of V. cholerae in foods. During an epidemic caused by V. cholerae O1 in Guinea‐Bissau in 1996, a case control study was conducted in the capital Bissau, the main affected region with an attack rate of 7.4%. Cases were hospitalized patients and controls were matched for area, gender and age. Lime juice in the sauce eaten with rice gave a strong protective effect (odds ratio [OR] = 0.31, 95% confidence interval [CI] = 0.17–0.56), and tomato sauce was also protective (OR = 0.36, 95% CI = 0.24–0.54). On the other hand, use of a bucket for storage of water in the house was associated with increased risk (OR = 4.4, CI = 2.21–8.74). Laboratory experiments to elucidate the inhibitory effect of different concentrations of lime juice on survival of V. cholerae in meals showed that V. cholerae thrives in rice with peanut sauce, but lime juice inhibited its growth. Since lime juice is a common ingredient of sauces, its use should be further encouraged to prevent foodborne transmission in the household during cholera outbreaks.

Maternal mortality: only 42 days?

Objective A maternal death is defined by WHO as ‘the death of a woman while pregnant or within 42 days of termination of pregnancy…’. The origin of the 42 days is no longer clear. In developing countries, the burden imposed by pregnancy and birth on a womans body may extend beyond 42 days as pregnancy‐related anaemia can persist for longer and vaginal haemorrhaging and risk of infections are not necessarily over after six weeks. We therefore examined duration of excess mortality after delivery in rural Guinea‐Bissau.

Factors associated with maternal mortality in rural Guinea‐Bissau. A longitudinal population‐based study

Objective To assess demographic and obstetric risk factors for pregnancy‐related death in a multiethnic rural population in a developing country.

HIV-1 infection prevalence and incidence trends in areas of contrasting levels of infection in the Kagera region, Tanzania, 1987-2000.

This study aimed at assessing the extent to which decline in HIV infection prevalence reflects decline in incidence in 3 areas with contrasting initial exposure to the HIV epidemic in the Kagera region of Tanzania. A population sample was recruited for the baseline study in 1987 through a multistage cluster sampling technique to determine HIV prevalence. Seronegative individuals identified in the baseline and subsequent studies were followed up for 3 years to yield trends in incidence that were compared for the 3 areas. The overall age-adjusted HIV-1 prevalence in the high-prevalence area of Bukoba urban declined significantly from 24.2% in 1987 to 18.2% in 1993 and later to 13.3% in 1996 (P = 0.0001). In the medium-prevalence area of Muleba, overall age-adjusted prevalence declined significantly from 10.0% in 1987 to 6.8% in 1996 and later to 4.3% in 1999 (P = 0.0003), whereas in the low-prevalence area of Karagwe the prevalence declined from 4.5% in 1987 to 2.6% in 1999 (P = 0.01). In all 3 areas, the most significant decline was consistently observed among women in the age group 15-24 years. No age group exhibited a significant upward prevalence trend. The HIV-1 incidence for Bukoba urban declined from 47.5 to 9.1 per 1000 person-years of observation in 1989 and 1996, respectively, whereas in Muleba it decreased from 8.2 to 3.9 in 1989 and 2000, respectively. Sex-specific estimates indicated a significant decline among women in the high-prevalence area of Bukoba urban from 51.5 to 9.2 per 1000 person-years at risk (P = 0.001). It is concluded that the HIV-1 epidemic in Kagera is on the decrease as reflected by the decline in HIV-1 incidence and prevalence trends particularly among the 15-24 year olds. The decline in the 3 areas of differing magnitude implies that the HIV/AIDS epidemic may be arrested early without necessarily peaking to saturation levels.

Survival among motherless children in rural and urban areas in Guinea-Bissau

Aim: With the increasing incidence of HIV and TB, motherless children are becoming a rapidly growing problem in Africa. However, few studies describe the survival patterns of these children. The aim of this study was to investigate the mortality of motherless children in urban and rural areas of Guinea‐Bissau. Methods: A historical cohort study was set up in urban and rural areas in Guinea‐Bissau. Motherless children were selected from two study cohorts under demographic surveillance since 1990. The relatives of 128 motherless children from the rural cohort and 192 from the urban area, as well as a total of 807 controls, were examined and interviewed. Results: Controlling for significant background factors revealed that motherless children had a markedly higher mortality than that of controls in both urban (mortality rate ratio (MR) 2.32 (95% confidence interval 1.11‐4.84)) and rural areas (MR = 4.16 (2.79‐6.22)). Virtually all the excess mortality occurred among children under 2 y of age when their mother died. Few motherless children had been provided with surrogate breastfeeding.