Browsing by Author "Tukahebwa, Edridah"

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    The Effect of Current Schistosoma Mansoni Infection on the Immunogenicity of A Candidate TB vaccine, MVA85A, in BCG Vaccinated Adolescents: An open-label trial
    (PLoS neglected tropical diseases, 2017) Wajja, Anne; Kizito, Dennison; Nassanga, Beatrice; Nalwoga, Angela; Kabagenyi, Joyce; Kimuda, Simon; Galiwango, Ronald; Mutonyi, Gertrude; Vermaak, Samantha; Tukahebwa, Edridah; McShane, Helen
    Helminth infection may affect vaccine immunogenicity and efficacy. Adolescents, a target population for tuberculosis booster vaccines, often have a high helminth burden. We investigated effects of Schistosoma mansoni (Sm) on the immunogenicity and safety of MVA85A, a model candidate tuberculosis vaccine, in BCG-vaccinated Ugandan adolescents.In this phase II open label trial we enrolled 36 healthy, previously BCG-vaccinated adolescents, 18 with no helminth infection detected, 18 with Sm only. The primary outcome was immunogenicity measured by Ag85A-specific interferon gamma ELISpot assay. Tuberculosis and schistosome-specific responses were also assessed by whole-blood stimulation and multiplex cytokine assay, and by antibody ELISAs.Ag85A-specific cellular responses increased significantly following immunisation but with no differences between the two groups. Sm infection was associated with higher pre-immunisation Ag85A-specific IgG4 but with no change in antibody levels following immunisation. There were no serious adverse events. Most reactogenicity events were of mild or moderate severity and resolved quickly.The significant Ag85A-specific T cell responses and lack of difference between Sm-infected and uninfected participants is encouraging for tuberculosis vaccine development. The implications of pre-existing Ag85A-specific IgG4 antibodies for protective immunity against tuberculosis among those infected with Sm are not known. MVA85A was safe in this population.
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    Ethical and Scientific Considerations on the Establishment of a Controlled Human Infection Model for Schistosomiasis in Uganda: report of a stakeholders’ meeting held in Entebbe, Uganda.
    (AAS open research, 2018) Elliott, Alison M.; Wajja, Anne; Opio, Christopher; Angumya, Francis; Adriko, Moses; Egesa, Moses; Mfutso-Bengo, Joseph; Kapulu, Melissa; Lutalo, Tom; Nazziwa, Winfred Badanga; Muwumuza, Asuman; Kaleebu, Pontiano; Kabatereine, Narcis; Tukahebwa, Edridah
    Controlled human infection (CHI) models are gaining recognition as an approach to accelerating vaccine development, for use in both non-endemic and endemic populations: they can facilitate identification of the most promising candidate vaccines for further trials and advance understanding of protective immunity. Helminths present a continuing health burden in sub-Saharan Africa. Vaccine development for these complex organisms is particularly challenging, partly because protective responses are akin to mechanisms of allergy. A CHI model for Schistosoma mansoni (CHI-S) has been developed at Leiden University Medical Centre, the Netherlands. However, responses to schistosome infections, and candidate vaccines, are likely to be different among people from endemic settings compared to schistosome-naïve Dutch volunteers. Furthermore, among volunteers from endemic regions who have acquired immune responses through prior exposure, schistosome challenge can be used to define responses associated with clinical protection, and thus to guide vaccine development. To explore the possibility of establishing the CHI-S in Uganda, a Stakeholders’ Meeting was held in Entebbe in 2017. Regulators, community members, researchers and policy-makers discussed implementation challenges and recommended preparatory steps: risk assessment; development of infrastructure and technical capacity to produce the infectious challenge material in Uganda; community engagement from Parliamentary to grass-roots level; pilot studies to establish approaches to assuring fully informed consent and true voluntariness, and strategies for selection of volunteers who can avoid natural infection during the 12-week CHI-S; the building of regulatory capacity; and the development of study protocols and a product dossier in close consultation with ethical and regulatory partners. It was recommended that, on completion, the protocol and product dossier be reviewed for approval in a joint meeting combining ethical, regulatory and environment management authorities. Most importantly, representatives of schistosomiasis-affected communities emphasised the urgent need for an effective vaccine and urged the research community not to delay in the development process.
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    The Impact of Intensive Versus Standard Anthelminthic Treatment on Allergy-related Outcomes, Helminth Infection Intensity, and Helminth-related Morbidity in Lake Victoria Fishing Communities, Uganda: Results From the LaVIISWA Cluster-randomized Trial
    (Clinical infectious diseases, 2019) Sanya, Richard E.; Nkurunungi, Gyaviira; Hoek Spaans, Remy; Nampijja, Margaret; O’Hara, Geraldine; Kizindo, Robert; Oduru, Gloria; Kabuubi Nakawungu, Prossy; Niwagaba, Emmanuel; Abayo, Elson; Kabagenyi, Joyce; Zziwa, Christopher; Tumusiime, Josephine; Nakazibwe, Esther; Kaweesa, James; Muwonge Kakooza, Fred; Akello, Mirriam; Lubyayi, Lawrence; Verweij, Jaco; Nash, Stephen; Ree, Ronald van; Mpairwe, Harriet; Tukahebwa, Edridah; Webb, Emily L.; Elliott, Alison M.
    The prevalence of allergy-related diseases is increasing in low-income countries. Parasitic helminths, common in these settings, may be protective. We hypothesized that intensive, community-wide, anthelminthic mass drug administration (MDA) would increase allergy-related diseases, while reducing helminth-related morbidity. Methods. In an open, cluster-randomized trial (ISRCTN47196031), we randomized 26 high-schistosomiasis-transmission fishing villages in Lake Victoria, Uganda, in a 1:1 ratio to receive community-wide intensive (quarterly single-dose praziquantel plus albendazole daily for 3 days) or standard (annual praziquantel plus 6 monthly single-dose albendazole) MDA. Primary outcomes were recent wheezing, skin prick test positivity (SPT), and allergen-specific immunoglobulin E (asIgE) after 3 years of intervention. Secondary outcomes included helminths, haemoglobin, and hepatosplenomegaly. Results. The outcome survey comprised 3350 individuals. Intensive MDA had no effect on wheezing (risk ratio [RR] 1.11, 95% confidence interval [CI] 0.64–1.93), SPT (RR 1.10, 95% CI 0.85–1.42), or asIgE (RR 0.96, 95% CI 0.82–1.12). Intensive MDA reduced Schistosoma mansoni infection intensity: the prevalence from Kato Katz examinations of single stool samples from each patient was 23% versus 39% (RR 0.70, 95% CI 0.55–0.88), but the urine circulating cathodic antigen test remained positive in 85% participants in both trial arms. Hookworm prevalence was 8% versus 11% (RR 0.55, 95% CI 0.31–1.00). There were no differences in anemia or hepatospenomegaly between trial arms. Conclusions. Despite reductions in S. mansoni intensity and hookworm prevalence, intensive MDA had no effect on atopy, allergy- related diseases, or helminth-related pathology. This could be due to sustained low-intensity infections; thus, a causal link between helminths and allergy outcomes cannot be discounted. Intensive community-based MDA has a limited impact in high-schistosomiasis- transmission fishing communities, in the absence of other interventions.
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    The Lake Victoria Island Intervention Study on Worms and Allergy-related diseases (LaVIISWA): Study Protocol for a Randomised Controlled Trial
    (Trials, 2015) Nampijja, Margaret; Webb, Emily L.; Kaweesa, James; Kizindo, Robert; Namutebi, Milly; Nakazibwe, Esther; Oduru, Gloria; Kabuubi, Prossy; Kabagenyi, Joyce; Kizito, Dennison; Muhangi, Lawrence; Akello, Mirriam; Verweij, Jaco J.; Nerima, Barbara; Tukahebwa, Edridah; Elliott, Alison M.
    The Hygiene Hypothesis proposes that infection exposure protects against inflammatory conditions. Helminths possess allergen-like molecules and may specifically modulate allergy-related immunological pathways to inhibit responses which protect against them. Mass drug administration is recommended for helminth-endemic communities to control helminth-induced pathology, but may also result in increased rates of inflammation-mediated diseases in resource-poor settings. Immunological studies integrated with implementation of helminth control measures may elucidate how helminth elimination contributes to ongoing epidemics of inflammatory diseases. We present the design of the Lake Victoria Island Intervention Study on Worms and Allergy-related diseases (LaVIISWA), a cluster-randomised trial evaluating the risks and benefits of intensive versus standard anthelminthic treatment for allergy-related diseases and other health outcomes.
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    Risk Assessment for the Implementation of Controlled Human Schistosoma Mansoni Infection Trials in Uganda
    (AAS open research, 2019) Koopman, Jan Pieter; Egesa, Moses; Wajja, Anne; Adriko, Moses; Nassuuna, Jacent; Nkurunungi, Gyaviira; Driciru, Emmanuella; Cose, Stephen; Kaleebu, Pontiano; Kabatereine, Narcis; Tukahebwa, Edridah; Elliott, Alison M.
    Schistosomiasis is a parasitic infection highly prevalent in sub-Saharan Africa, and a significant cause of morbidity; it is a priority for vaccine development. A controlled human infection model for Schistosoma mansoni (CHI-S) with potential to accelerate vaccine development has been developed among naïve volunteers in the Netherlands. Because responses both to infections and candidate vaccines are likely to differ between endemic and non-endemic settings, we propose to establish a CHI-S in Uganda where Schistosoma mansoni is endemic. As part of a “road-map” to this goal, we have undertaken a risk assessment. We identified risks related to importing of laboratory vector snails and schistosome strains from the Netherlands to Uganda; exposure to natural infection in endemic settings concurrently with CHI-S studies, and unfamiliarity of the community with the nature, risks and rationale for CHI. Mitigating strategies are proposed. With careful implementation of the latter, we believe that CHI-S can be implemented safely in Uganda. Our reflections are presented here to promote feedback and discussion.