Economics of rainwater harvesting for crop enterprises in semi-arid areas: the case of Makanya Watershed in Pangani River Basin, Tanzania

River basinsWatershedsRainWater harvestingVillagesMaizeBeansRunoffEconomic aspects

Economics of rainwater harvesting for crop enterprises in semi-arid areas: the case of Makanya Watershed in Pangani River Basin, Tanzania

River basinsWatershedsRainWater harvestingVillagesMaizeBeansRunoff

Use of a hydrological model for environmental management of the Usangu Wetlands, Tanzania

Wetlands / Rivers / Ecology / Environmental effects / Remote sensing / Hydrology / Simulation models / Water budget / Irrigated sites / Land cover / Time series analysis / Tanzania / Usangu Wetlands / Great Ruaha River

Role of human Pegivirus infections in whole; Plasmodium falciparum; sporozoite vaccination and controlled human malaria infection in African volunteers

BACKGROUND: Diverse vaccination outcomes and protection levels among different populations pose a serious challenge to the development of an effective malaria vaccine. Co-infections are among many factors associated with immune dysfunction and sub-optimal vaccination outcomes. Chronic, asymptomatic viral infections can contribute to the modulation of vaccine efficacy through various mechanisms. Human Pegivirus-1 (HPgV-1) persists in immune cells thereby potentially modulating immune responses. We investigated whether Pegivirus infection influences vaccine-induced responses and protection in African volunteers undergoing whole P. falciparum sporozoites-based malaria vaccination and controlled human malaria infections (CHMI). METHODS: HPgV-1 prevalence was quantified by RT-qPCR in plasma samples of 96 individuals before, post vaccination with PfSPZ Vaccine and after CHMI in cohorts from Tanzania and Equatorial Guinea. The impact of HPgV-1 infection was evaluated on (1) systemic cytokine and chemokine levels measured by Luminex, (2) PfCSP-specific antibody titers quantified by ELISA, (3) asexual blood-stage parasitemia pre-patent periods and parasite multiplication rates, (4) HPgV-1 RNA levels upon asexual blood-stage parasitemia induced by CHMI. RESULTS: The prevalence of HPgV-1 was 29.2% (28/96) and sequence analysis of the 5' UTR and E2 regions revealed the predominance of genotypes 1, 2 and 5. HPgV-1 infection was associated with elevated systemic levels of IL-2 and IL-17A. Comparable vaccine-induced anti-PfCSP antibody titers, asexual blood-stage multiplication rates and pre-patent periods were observed in HPgV-1 positive and negative individuals. However, a tendency for higher protection levels was detected in the HPgV-1 positive group (62.5%) compared to the negative one (51.6%) following CHMI. HPgV-1 viremia levels were not significantly altered after CHMI. CONCLUSIONS: HPgV-1 infection did not alter PfSPZ Vaccine elicited levels of PfCSP-specific antibody responses and parasite multiplication rates. Ongoing HPgV-1 infection appears to improve to some degree protection against CHMI in PfSPZ-vaccinated individuals. This is likely through modulation of immune system activation and systemic cytokines as higher levels of IL-2 and IL17A were observed in HPgV-1 infected individuals. CHMI is safe and well tolerated in HPgV-1 infected individuals. Identification of cell types and mechanisms of both silent and productive infection in individuals will help to unravel the biology of this widely present but largely under-researched virus

HIV Infection Functionally Impairs Mycobacterium tuberculosis-Specific CD4 and CD8 T-Cell Responses.

Human immunodeficiency virus (HIV) infection is the major risk factor predisposing for Mycobacterium tuberculosis progression from latent tuberculosis infection (LTBI) to tuberculosis disease (TB). Since long-term-treated aviremic HIV-infected individuals remained at higher risk of developing TB than HIV-uninfected individuals, we hypothesized that progression from LTBI to pulmonary TB (PTB) might be due not only to CD4 T-cell depletion but also to M. tuberculosis-specific CD4 T-cell functional impairment. To test this hypothesis, M. tuberculosis-specific T-cell frequencies and cytokine profiles were investigated in untreated Tanzanian individuals suffering from LTBI (n = 20) or PTB (n = 67) and compared to those of untreated M. tuberculosis/HIV-coinfected individuals suffering from LTBI (n = 15) or PTB (n = 10). We showed that HIV infection significantly reduced the proportion of Th2 (interleukin 4 [IL-4]/IL-5/IL-13) producing M. tuberculosis-specific CD4 T cells and IL-2-producing M. tuberculosis-specific CD4 and CD8 T cells in individuals with LTBI or PTB (P < 0.05). Interestingly, the loss of IL-2 production was associated with a significant increase of PD-1 expression on M. tuberculosis-specific CD4 and CD8 T cells (P < 0.05), while the loss of Th2 cytokine production was associated with a significant reduction of Gata-3 expression in memory CD4 T cells (P < 0.05). Finally, we showed that the serum levels of IL-1α, IL-6, C-reactive protein (CRP), IL-23, and IP-10 were significantly reduced in M. tuberculosis/HIV-coinfected individuals with PTB compared to those in HIV-negative individuals with PTB (P < 0.05), suggesting that HIV infection significantly suppresses M. tuberculosis-induced systemic proinflammatory cytokine responses. Taken together, this study suggests that in addition to depleting M. tuberculosis-specific CD4 T cells, HIV infection significantly impairs functionally favorable M. tuberculosis-specific CD4 T-cell responses in Tanzanian individuals with LTBI or PTB.IMPORTANCEMycobacterium tuberculosis and human immunodeficiency virus (HIV) infections are coendemic in several regions of the world, and M. tuberculosis/HIV-coinfected individuals are more susceptible to progression to tuberculosis disease. We therefore hypothesized that HIV infection would potentially impair M. tuberculosis-specific protective immunity in individuals suffering from latent tuberculosis infection (LTBI) or active pulmonary tuberculosis (PTB). In this study, we demonstrated that M. tuberculosis/HIV-coinfected individuals have fewer circulating M. tuberculosis-specific CD4 T cells and that those that remained were functionally impaired in both LTBI and PTB settings. In addition, we showed that HIV infection significantly interferes with M. tuberculosis-induced systemic proinflammatory cytokine/chemokine responses. Taken together, these data suggest that HIV infection impairs functionally favorable M. tuberculosis-specific immunity

Safety and immunogenicity of radiation-attenuated PfSPZ vaccine in equatoguinean infants, children, and adults

The radiation-attenuated Plasmodium falciparum sporozoites (PfSPZ) Vaccine has demonstrated safety and immunogenicity in 5-month-old to 50-year-old Africans in multiple trials. Except for one, each trial has restricted enrollment to either infants and children or adults /= 0.17). There were no significant differences between vaccinees and controls with respect to the rates or severity of unsolicited AEs or laboratory abnormalities. Development of antibodies to P. falciparum circumsporozoite protein occurred in 67/69 vaccinees (97%) and 0/15 controls. Median antibody levels were highest in infants and 1-5-year-olds and declined progressively with age. Antibody responses in children were greater than in adults protected against controlled human malaria infection. Robust immunogenicity, combined with a benign AE profile, indicates children are an ideal target for immunization with PfSPZ Vaccine

Mixed Th1 and Th2 Mycobacterium tuberculosis-specific CD4 T cell responses in patients with active pulmonary tuberculosis from Tanzania.

Mycobacterium tuberculosis (Mtb) and helminth infections elicit antagonistic immune effector functions and are co-endemic in several regions of the world. We therefore hypothesized that helminth infection may influence Mtb-specific T-cell immune responses. We evaluated the cytokine profile of Mtb-specific T cells in 72 individuals with pulmonary TB disease recruited from two Sub-Saharan regions with high and moderate helminth burden i.e. 55 from Tanzania (TZ) and 17 from South Africa (SA), respectively. We showed that Mtb-specific CD4 T-cell functional profile of TB patients from Tanzania are primarily composed of polyfunctional Th1 and Th2 cells, associated with increased expression of Gata-3 and reduced expression of T-bet in memory CD4 T cells. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by single IFN-γ and dual IFN-γ/TNF-α and associated with TB-induced systemic inflammation and elevated serum levels of type I IFNs. Of note, the proportion of patients with Mtb-specific CD8 T cells was significantly reduced in Mtb/helminth co-infected patients from TZ. It is likely that the underlying helminth infection and possibly genetic and other unknown environmental factors may have caused the induction of mixed Th1/Th2 Mtb-specific CD4 T cell responses in patients from TZ. Taken together, these results indicate that the generation of Mtb-specific CD4 and CD8 T cell responses may be substantially influenced by environmental factors in vivo. These observations may have major impact in the identification of immune biomarkers of disease status and correlates of protection

Understanding resilience of female adolescents towards teenage pregnancy: a cross-sectional survey in Dar es Salaam, Tanzania

Abstract Background In Tanzania, teenage pregnancy rates are still high despite the efforts being made to reduce them. Not enough is known about how adolescents experience and cope with sexuality and teenage pregnancy. Over the past few decades, most studies have focused on vulnerability and risk among youth. The concept of ‘reproductive resilience’ is a new way of looking at teenage pregnancy. It shifts the perspective from a deficit-based to a strength-based approach. The study presented here aimed to identify factors that could contribute to strengthening the reproductive resilience of girls in Dar es Salaam, Tanzania. Methods Using a cross-sectional cluster sampling approach, 750 female adolescents aged 15–19 years were interviewed about how they mobilize resources to avoid or deal with teenage pregnancy. The main focus of the study was to examine how social capital (relations with significant others), economic capital (command over economic resources), cultural capital (personal dispositions and habits), and symbolic capital (recognition and prestige) contribute to the development of adolescent competencies for avoiding or dealing with teenage pregnancy and childbirth. Results A cumulative competence scale was developed to assess reproductive resilience. The cumulative score was computed based on 10 competence indicators that refer to the re- and pro-active mobilization of resources. About half of the women who had never been pregnant fell into the category, ‘high competence’ (50.9%), meaning they could get the information and support needed to avoid pregnancies. Among pregnant women and young mothers, most were categorized as ‘high competence’ (70.5%) and stated that they know how to avoid or deal with health problems that might affect them or their babies, and could get the information and support required to do so. Cultural capital, in particular, contributed to the competence of never-pregnant girls [OR = 1.80, 95% CI = 1.06 to 3.07, p = 0.029], pregnant adolescents and young mothers [OR = 3.33, 95% CI = 1.15 to 9.60, p = 0.026]. Conclusions The reproductive resilience framework provides new insights into the reproductive health realities of adolescent girls from a strength-based perspective. While acknowledging that teenage pregnancy has serious negative implications for many female adolescents, the findings presented here highlight the importance of considering girls’ capacities to prevent or deal with teenage pregnancy