Browsing by Subject "Surveys"

Now showing 1 - 4 of 4
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    Open Access
    HIV prevalence by race co-varies closely with concurrency and number of sex partners in South Africa
    (Public Library of Science, 2013) Kenyon, Chris; Buyze, Jozefien; Colebunders, Robert
    BACKGROUND: HIV prevalence differs by more than an order of magnitude between South Africa's racial groups. Comparing the sexual behaviors and other risk factors for HIV transmission between the different races may shed light on the determinants of South Africa's generalized HIV epidemic. METHODS: Five nationally representative and one city-representative population-based surveys of sexual behavior were used to assess the extent to which various risk factors co-varied with HIV prevalence by race in South Africa. RESULTS: In 2004, the prevalence of HIV was 0.5%, 1%, 3.2% and 19.9% in 15-49 year old whites, Indians, coloureds and blacks respectively. The risk factors which co-varied with HIV prevalence by race in the six surveys were age of sexual debut (in five out of five surveys for men and three out of six surveys for women), age gap (zero surveys in men and three in women), mean number of sex partners in the previous year (five surveys in men and three in women) and concurrent partnerships (five surveys in men and one in women). Condom usage and circumcision were both more prevalent in the high HIV prevalence groups. The reported prevalence of concurrency was 6 to 17 times higher in the black as opposed to the white men in the five surveys. CONCLUSIONS: The differences in sexual behavior in general, and the prevalence of concurrency and the number of sexual partners in particular, offer a plausible and parsimonious cause to explain a part of the differing prevalences of HIV between South Africa's racial groups.
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    HIV prevalence correlates with high-risk sexual behavior in Ethiopia's regions
    (Public Library of Science, 2015) Kenyon, Chris R; Tsoumanis, Achilleas; Schwartz, Ilan Steven
    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.
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    Male circumcision and sexual risk behaviors may contribute to considerable ethnic disparities in HIV prevalence in Kenya: an ecological analysis
    (Public Library of Science, 2014) Kenyon, Chris Richard; Vu, Lung; Menten, Joris; Maughan-Brown, Brendan
    BACKGROUND: HIV prevalence varies between 0.8 and 20.2% in Kenya's various ethnic groups. The reasons underlying these variations have not been evaluated before. METHODS: We used data from seven national surveys spanning the period 1989 to 2008 to compare the prevalence of a range of risk factors in Kenya's ethnic groups. Spearman's and linear regression were used to assess the relationship between HIV prevalence and each variable by ethnic group. RESULTS: The ethnic groups exhibited significant differences in a number of HIV related risk factors. Although the highest HIV prevalence group (the Luo) had the highest rates of HIV testing (Men 2008 survey: 56.8%, 95% CI 51.0-62.5%) and condom usage at last sex (Men 2008∶28.6%, 95% CI 19.6-37.6%), they had the lowest prevalence of circumcision (20.9%, 95% CI 15.9-26.0) the highest prevalence of sex with a non-married, non-cohabiting partner (Men: 40.2%, 95% CI 33.2-47.1%) and pre-marital sex (Men 2008∶73.9%, 95% CI 67.5-80.3%) and the youngest mean age of debut for women (1989 Survey: 15.7 years old, 95% CI 15.2-16.2). At a provincial level there was an association between the prevalence of HIV and male concurrency (Spearman's rho = 0.79, P = 0.04). Ethnic groups with higher HIV prevalence were more likely to report condom use (Men 2008 survey: R2 = 0.62, P = 0.01) and having been for HIV testing (Men 2008 survey: R2 = 0.47, P = 0.04). CONCLUSION: In addition to differences in male circumcision prevalence, variation in sexual behavior may contribute to the large variations in HIV prevalence in Kenya's ethnic groups. To complement the prevention benefits of the medical male circumcision roll-out in several parts of Kenya, interventions to reduce risky sexual behavior should continue to be promoted.
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    Scent lure effect on camera-trap based leopard density estimates
    (Public Library of Science, 2016) Braczkowski, Alexander Richard; Balme, Guy Andrew; Dickman, Amy; Fattebert, Julien; Johnson, Paul; Dickerson, Tristan; Macdonald, David Whyte; Hunter, Luke
    Density estimates for large carnivores derived from camera surveys often have wide confidence intervals due to low detection rates. Such estimates are of limited value to authorities, which require precise population estimates to inform conservation strategies. Using lures can potentially increase detection, improving the precision of estimates. However, by altering the spatio-temporal patterning of individuals across the camera array, lures may violate closure, a fundamental assumption of capture-recapture. Here, we test the effect of scent lures on the precision and veracity of density estimates derived from camera-trap surveys of a protected African leopard population. We undertook two surveys (a 'control' and 'treatment' survey) on Phinda Game Reserve, South Africa. Survey design remained consistent except a scent lure was applied at camera-trap stations during the treatment survey. Lures did not affect the maximum movement distances (p = 0.96) or temporal activity of female (p = 0.12) or male leopards (p = 0.79), and the assumption of geographic closure was met for both surveys (p >0.05). The numbers of photographic captures were also similar for control and treatment surveys (p = 0.90). Accordingly, density estimates were comparable between surveys (although estimates derived using non-spatial methods (7.28-9.28 leopards/100km 2 ) were considerably higher than estimates from spatially-explicit methods (3.40-3.65 leopards/100km 2 ). The precision of estimates from the control and treatment surveys, were also comparable and this applied to both non-spatial and spatial methods of estimation. Our findings suggest that at least in the context of leopard research in productive habitats, the use of lures is not warranted.