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Schistosomiasis is a leading cause of morbidity in Africa. Understanding the disease ecology and environmental factors that influence its distribution is important to guide control efforts. Geographic information systems have increasingly been used in the field of schistosomiasis environmental epidemiology. This study reports prevalences of Schistosoma haematobium infection and uses remotely sensed and questionnaire data from over 17000 participants to identify environmental and socio-demographic factors that are associated with this parasitic infection. Data regarding socio-demographic status and S. haematobium infection were obtained between May 2006 and May 2007 from 17280 participants (53% females, median age = 17 years) in the Mbeya Region, Tanzania. Combined with remotely sensed environmental data (vegetation cover, altitude, rainfall etc.) this data was analyzed to identify environmental and socio-demographic factors associated with S. haematobium infection, using mixed effects logistic regression and geostatistical modelling. The overall prevalence of S. haematobium infection was 5.3% (95% confidence interval (CI): 5.0–5.6%). Multivariable analysis revealed increased odds of infection for school-aged children (5–15 years, odds ratio (OR) = 7.8, CI: 5.9–10.4) and the age groups 15–25 and 25–35 years (15–25 years: OR = 5.8, CI: 4.3–8.0, 25–35 years: OR = 1.6, CI: 1.1–2.4) compared to persons above 35 years of age, for increasing distance to water courses (OR = 1.4, CI: 1.2–1.6 per km) and for proximity to Lake Nyasa (4 km. Odds of infection decreased with higher altitude (OR = 0.7, CI: 0.6–0.8 per 100 m increase) and with increasing enhanced vegetation index EVI (OR = 0.2, CI: 0.1–0.4 per 0.1 units). When additionally adjusting for spatial correlation population density became a significant predictor of schistosomiasis infection (OR = 1.3, CI: 1.1–1.5 per 1000 persons/km2) and altitude turned non-significant. We found highly focal geographical patterns of S. haematobium infection in Mbeya Region in Southwestern Tanzania. Despite low overall prevalence our spatially heterogeneous results show that some of the study sites suffer from a considerable burden of S. haematobium infection, which is related to various socio-demographic and environmental factors. Our results could help to design more effective control strategies in the future, especially targeting school-aged children living in low altitude sites and/or crowded areas as the persons at highest need for preventive chemotherapy., Author summary Urinary schistosomiasis caused by the parasitic blood fluke Schistosoma haematobium is an important public health concern in the tropics and subtropics. Freshwater snails of the genus Bulinus are the intermediate hosts and infection is acquired by contact with fresh water inhabited by infected snails. This means that transmission of the parasite strongly depends on environmental factors, which we wanted to explore in this study. Individually assessed questionnaire and laboratory data from a study in Mbeya Region in Southwestern Tanzania were combined with remotely sensed and other environmental data that were publicly available. We found that the odds of urinary schistosomiasis were higher in school-aged children and young adults than in older age groups and in children below 5 years. Odds of infection were also higher at lower altitudes, in areas with less vegetation and in the vicinity of Lake Nyasa. These results add to the general knowledge regarding S. haematobium infection and could help to design more effective control strategies in the future, both locally and on larger scales.

Background Annual mass treatment with ivermectin and albendazole is used to treat lymphatic filariasis in many African countries, including Tanzania. In areas where both diseases occur, it is unclear whether HIV co-infection reduces treatment success. Methodology In a general population study in Southwest Tanzania, individuals were tested for HIV and circulating filarial antigen, an indicator of Wuchereria bancrofti adult worm burden, before the first and after 2 consecutive rounds of anti-filarial mass drug administration. Principle Findings Testing of 2104 individuals aged 0–94 years before anti-filarial treatment revealed a prevalence of 24.8% for lymphatic filariasis and an HIV-prevalence of 8.9%. Lymphatic filariasis was rare in children, but prevalence increased in individuals above 10 years, whereas a strong increase in HIV was only seen above 18 years of age. The prevalence of lymphatic filariasis in adults above 18 years was 42.6% and 41.7% (p = 0.834) in HIV-negatives and–positives, respectively. Similarly, the HIV prevalence in the lymphatic filariasis infected (16.6%) and uninfected adult population (17.1%) was nearly the same. Of the above 2104 individuals 798 were re-tested after 2 rounds of antifilarial treatment. A significant reduction in the prevalence of circulating filarial antigen from 21.6% to 19.7% was found after treatment (relative drop of 8.8%, McNemar´s exact p = 0.036). Furthermore, the post-treatment reduction of CFA positivity was (non-significantly) larger in HIV-positives than in HIV-negatives (univariable linear regression p = 0.154). Conclusion/Significance In an area with a high prevalence for both diseases, no difference was found between HIV-infected and uninfected individuals regarding the initial prevalence of lymphatic filariasis. A moderate but significant reduction in lymphatic filariasis prevalence and worm burden was demonstrated after two rounds of treatment with albendazole and ivermectin. Treatment effects were more pronounced in the HIV co-infected subgroup, indicating that the effectiveness of antifilarial treatment was not reduced by concomitant HIV-infection. Studies with longer follow-up time could validate the observed differences in treatment effectiveness., Author Summary Parasite infections and HIV show large geographical overlap in sub-Saharan Africa and could hence potentially interact in co-infected individuals. In a general-population study conducted in Southwest Tanzania, we found high prevalence of both, lymphatic filariasis and HIV, with 42.5% of the adult population infected with Wuchereria bancrofti and 16.8% infected with HIV. Seven percent of the adults were infected with both pathogens. When adjusting for age, there was no statistically significant difference in initial prevalence or worm burden between HIV-positive and negative participants. For 798 individuals test results for both diseases were available in 2009, before and in 2011, after 2 rounds of treatment against lymphatic filariasis. Between 2009 and 2011, a significant drop of prevalence and worm burden in infected individuals were observed, which was more pronounced in the HIV co-infected subgroup. Hence, HIV co-infection does not seem to negatively affect lymphatic filariasis treatment programmes.

It is well accepted that aging and HIV infection are associated with quantitative and functional changes of CMV-specific T cell responses. We studied here the expression of Mip-1β and the T cell maturation marker CD27 within CMVpp65-specific CD4(+) and CD8(+) T cells in relation to age, HIV and active Tuberculosis (TB) co-infection in a cohort of Tanzanian volunteers (≤ 16 years of age, n = 108 and ≥ 18 years, n = 79). Independent of HIV co-infection, IFNγ(+) CMVpp65-specific CD4(+) T cell frequencies increased with age. In adults, HIV co-infection further increased the frequencies of these cells. A high capacity for Mip-1β production together with a CD27(low) phenotype was characteristic for these cells in children and adults. Interestingly, in addition to HIV co-infection active TB disease was linked to further down regulation of CD27 and increased capacity of Mip-1β production in CMVpp65-specific CD4+ T cells. These phenotypic and functional changes of CMVpp65-specific CD4 T cells observed during HIV infection and active TB could be associated with increased CMV reactivation rates.

Background Hookworm disease is one of the most common infections and cause of a high disease burden in the tropics and subtropics. Remotely sensed ecological data and model-based geostatistics have been used recently to identify areas in need for hookworm control. Methodology Cross-sectional interview data and stool samples from 6,375 participants from nine different sites in Mbeya region, south-western Tanzania, were collected as part of a cohort study. Hookworm infection was assessed by microscopy of duplicate Kato-Katz thick smears from one stool sample from each participant. A geographic information system was used to obtain remotely sensed environmental data such as land surface temperature (LST), vegetation cover, rainfall, and elevation, and combine them with hookworm infection data and with socio-demographic and behavioral data. Uni- and multivariable logistic regression was performed on sites separately and on the pooled dataset. Principal Findings Univariable analyses yielded significant associations for all ecological variables. Five ecological variables stayed significant in the final multivariable model: population density (odds ratio (OR) = 0.68; 95% confidence interval (CI) = 0.63–0.73), mean annual vegetation density (OR = 0.11; 95% CI = 0.06–0.18), mean annual LST during the day (OR = 0.81; 95% CI = 0.75–0.88), mean annual LST during the night (OR = 1.54; 95% CI = 1.44–1.64), and latrine coverage in household surroundings (OR = 1.02; 95% CI = 1.01–1.04). Interaction terms revealed substantial differences in associations of hookworm infection with population density, mean annual enhanced vegetation index, and latrine coverage between the two sites with the highest prevalence of infection. Conclusion/Significance This study supports previous findings that remotely sensed data such as vegetation indices, LST, and elevation are strongly associated with hookworm prevalence. However, the results indicate that the influence of environmental conditions can differ substantially within a relatively small geographic area. The use of large-scale associations as a predictive tool on smaller scales is therefore problematic and should be handled with care., Author Summary Hookworm disease, caused by the nematodes Ancylostoma duodenale and Necator americanus, is an important cause of maternal and child morbidity in the developing countries of the tropics and subtropics. In children, hookworm disease has been shown to potentially result in growth retardation as well as intellectual and cognitive impairments. In a cross-sectional survey in Mbeya region, Tanzania, we assessed the effects of possible risk factors for hookworm infection with a focus on remotely sensed ecological factors such as elevation, vegetation density, land surface temperature, and rainfall. We found that several ecological variables were significantly associated with hookworm infection. However, differing effects for these factors were estimated when performing the analyses separately for the two sites with the highest hookworm prevalence. Our study shows that effects are scale-dependent and that prediction at smaller scales using large-scale data and vice versa should be handled with caution, because regional variation can substantially influence the presence of hookworm infection.