A greater knowledge of the burden of HIV in rural areas of Southern Africa is needed, especially among older adults. We conducted a cross-sectional biomarker survey in the rural South African Agincourt Health and Sociodemographic Surveillance site in 2010–2011 and estimated HIV prevalence and risk factors. Using an age–sex stratified random sample of ages 15 +, a total of 5037 (65.7%) of a possible 7662 individuals were located and 4362 (86.6%) consented to HIV testing. HIV prevalence was high (19.4%) and characterized by a large gender gap (10.6% for men and 23.9% for women). Rates peaked at 45.3% among men and 46.1% among women – both at ages 35–39. Compared with a similar study in the rural KwaZulu-Natal Province, South Africa, peak prevalence occurred at later ages, and HIV prevalence was higher among older adults – with rates above 15% for men and 10% for women through to age 70. High prevalence continues to characterize Southern Africa, and recent evidence confirms that older adults cannot be excluded from policy considerations. The high prevalence among older adults suggests likely HIV infection at older ages. Prevention activities need to expand to older adults to reduce new infections. Treatment will be complicated by increased risk of noncommunicable diseases and by increasing numbers of older people living with HIV.

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Distributions of common species of Eucalyptus in south-eastem Australia are related to gradients in temperature and rainfall. To determine whether intrinsic water-use efficiency (as indexed by carbon isotope discrimination, A) or other leaf attributes were related to climate of native habitats, we sampled 17 populations representing 14 species of Eucalyptus growing in a common garden in southcentral New South Wales. Phreatophytes were clearly distinguished from populations that are totally dependent upon soil moisture derived from rainfall by having higher A at a particular level of rainfall. Among 12 non-phreatophytic populations (11 species), A was positively correlated with mean annual precipitation ( r = 0.75, P = 0.005), December-March precipitation ( r = 0.79, P = 0.002), an index of annual soil moisture ( r = 0.81, P = 0.001) and seasonality of precipitation ( r = 0.85, P < 0.001). There were similarly strong but negative correlations between A and potential evaporation during the summer months, but A was not correlated with annual potential evaporation of the source sites. Leaf mass per unit area (pe) was negatively correlated with indices of water availability, positively correlated with nitrogen per unit leaf area ( r = 0.90, P < 0.001), and negatively correlated with A ( r = -0.73, P = 0.007). A was negatively correlated with area-based leaf nitrogen ( r = -0.79, P = 0.002). These complementary correlations among A, p,, and nitrogen per unit leaf area indicate that variation in A may stem largely from variation in photosynthetic capacity. The results provide strong evidence that variation in A and p, reflect genetic adaptations to native habitats.

BackgroundTo inform health care and training, resource and research priorities, it is essential to establish how non-communicable disease risk factors vary by HIV-status in high HIV burden areas; and whether long-term anti-retroviral therapy (ART) plays a modifying role.MethodsAs part of a cohort initiation, we conducted a baseline HIV/cardiometabolic risk factor survey in 2010–2011 using an age-sex stratified random sample of ages 15+ in rural South Africa. We modelled cardiometabolic risk factors and their associations by HIV-status and self-reported ART status for ages 18+ using sex-stratified logistic regression models.ResultsAge-standardised HIV prevalence in women was 26% (95% CI 24-28%) and 19% (95% CI 17–21) in men. People with untreated HIV were less likely to have a high waist circumference in both women (OR 0.67; 95% CI 0.52-0.86) and men (OR 0.42; 95% CI 0.22-0.82). Untreated women were more likely to have low HDL and LDL, and treated women high triglycerides. Cardiometabolic risk factors increased with age except low HDL. The prevalence of hypertension was high (40% in women; 30% in men).ConclusionsSub-Saharan Africa is facing intersecting epidemics of HIV and hypertension. In this setting, around half the adult population require long-term care for at least one of HIV, hypertension or diabetes. Together with the adverse effects that HIV and its treatment have on lipids, this may have serious implications for the South African health care system. Monitoring of the interaction of HIV, ART use, and cardiometabolic disease is needed at both individual and population levels.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-015-1467-1) contains supplementary material, which is available to authorized users.