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  • JOURNAL ARTICLE
    Turner HC, Truscott JE, Bettis AA, Farrell SH, Deol AK, Whitton JM, Fleming FM, Anderson RM, Turner HC, Truscott JE, Bettis AA, Farrell SH, Deol AK, Whitton JM, Fleming FM, Anderson RM, Turner HC, Truscott JE, Bettis AA, Farrell SH, Deol AK, Whitton JM, Fleming FM, Anderson RM, Turner HC, Truscott JE, Bettis AA, Farrell SH, Deol AK, Whitton JM, Fleming FM, Anderson RM, Turner HC, Truscott JE, Bettis AA, Farrell SH, Deol AK, Whitton JM, Fleming FM, Anderson RM, Turner HC, Truscott JE, Bettis AA, Farrell SH, Deol AK, Whitton JM, Fleming FM, Anderson RMet al., 2017,

    Evaluating the variation in the projected benefit of community-wide mass treatment for schistosomiasis: Implications for future economic evaluations

    , PARASITES & VECTORS, Vol: 10, ISSN: 1756-3305

    BACKGROUND: The majority of schistosomiasis control programmes focus on targeting school-aged children. Expanding the use of community-wide mass treatment to reach more adults is under consideration. However, it should be noted that this would require a further increase in programmatic resources, international aid, and commitment for the provision of praziquantel. Consequently, it is important to understand (i) where a change of strategy would have the greatest benefit, and (ii) how generalisable the conclusions of field trials and analytical studies based on mathematical models investigating the impact of community-wide mass treatment, are to a broad range of settings. METHODS: In this paper, we employ a previously described deterministic fully age-structured schistosomiasis transmission model and evaluate the benefit of community-wide mass treatment both in terms of controlling morbidity and eliminating transmission for Schistosoma mansoni, across a wide range of epidemiological settings and programmatic scenarios. This included variation in the baseline relative worm pre-control burden in adults, the overall level of transmission in defined settings, choice of effectiveness metric (basing morbidity calculations on prevalence or intensity), the level of school enrolment and treatment compliance. RESULTS: Community-wide mass treatment was found to be more effective for controlling the transmission of schistosome parasites than using a school-based programme only targeting school-aged children. However, in the context of morbidity control, the potential benefit of switching to community-wide mass treatment was highly variable across the different scenarios analysed. In contrast, for areas where the goal is to eliminate transmission, the projected benefit of community-wide mass treatment was more consistent. CONCLUSION: Whether community-wide mass treatment is appropriate will depend on the local epidemiological setting (i.e. the relative pre-control burden in adults

  • JOURNAL ARTICLE
    Chami GF, Kontoleon AA, Bulte E, Fenwick A, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Kontoleon AA, Bulte E, Fenwick A, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Kontoleon AA, Bulte E, Fenwick A, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Kontoleon AA, Bulte E, Fenwick A, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Kontoleon AA, Bulte E, Fenwick A, Kabatereine NB, Tukahebwa EM, Dunne DWet al., 2016,

    Profiling Nonrecipients of Mass Drug Administration for Schistosomiasis and Hookworm Infections: A Comprehensive Analysis of Praziquantel and Albendazole Coverage in Community-Directed Treatment in Uganda

    , CLINICAL INFECTIOUS DISEASES, Vol: 62, Pages: 200-207, ISSN: 1058-4838

    BACKGROUND: Repeated mass drug administration (MDA) with preventive chemotherapies is the mainstay of morbidity control for schistosomiasis and soil-transmitted helminths, yet the World Health Organization recently reported that less than one-third of individuals who required preventive chemotherapies received treatment. METHODS: Coverage of community-directed treatment with praziquantel (PZQ) and albendazole (ALB) was analyzed in 17 villages of Mayuge District, Uganda. National drug registers, household questionnaires, and parasitological surveys were collected to track 935 individuals before and after MDA. Multilevel logistic regressions, including household and village effects, were specified with a comprehensive set of socioeconomic and parasitological variables. The factors predicting who did not receive PZQ and ALB from community medicine distributors were identified. RESULTS: Drug receipt was correlated among members within a household, and nonrecipients of PZQ or ALB were profiled by household-level socioeconomic factors. Individuals were less likely to receive either PZQ or ALB if they had a Muslim household head or low home quality, belonged to the minority tribe, or had settled for more years in their village. Untreated individuals were also more likely to belong to households that did not purify drinking water, had no home latrine, and had no members who were part of the village government. CONCLUSIONS: The findings demonstrate how to locate and target individuals who are not treated in MDA. Infection risk factors were not informative. In particular, age, gender, and occupation were unable to identify non-recipients, although World Health Organization guidelines rely on these factors. Individuals of low socioeconomic status, minority religions, and minority tribes can be targeted to expand MDA coverage.

  • JOURNAL ARTICLE
    Deol A, Webster JP, Walker M, Basanez M-G, Hollingsworth TD, Fleming FM, Montresor A, French MD, Deol A, Webster JP, Walker M, Basáñez M-G, Hollingsworth TD, Fleming FM, Montresor A, French MD, Deol A, Webster JP, Walker M, Basáñez MG, Hollingsworth TD, Fleming FM, Montresor A, French MD, Deol A, Webster JP, Walker M, Basáñez M-G, Hollingsworth TD, Fleming FM, Montresor A, French MD, Deol A, Webster JP, Walker M, Basáñez M-G, Hollingsworth TD, Fleming FM, Montresor A, French MD, Deol AK, Webster JP, walker M, Basáñez MG, Hollingsworth TD, Fleming F, Montresor A, French Met al., 2016,

    Development and evaluation of a Markov model to predict changes in schistosomiasis prevalence in response to praziquantel treatment: a case study of Schistosoma mansoni in Uganda and Mali

    , PARASITES & VECTORS, Vol: 9, Pages: 543-15, ISSN: 1756-3305

    BACKGROUND: Understanding whether schistosomiasis control programmes are on course to control morbidity and potentially switch towards elimination interventions would benefit from user-friendly quantitative tools that facilitate analysis of progress and highlight areas not responding to treatment. This study aimed to develop and evaluate such a tool using large datasets collected during Schistosomiasis Control Initiative-supported control programmes. METHODS: A discrete-time Markov model was developed using transition probability matrices parameterized with control programme longitudinal data on Schistosoma mansoni obtained from Uganda and Mali. Four matrix variants (A-D) were used to compare different data types for parameterization: A-C from Uganda and D from Mali. Matrix A used data at baseline and year 1 of the control programme; B used year 1 and year 2; C used baseline and year 1 from selected districts, and D used baseline and year 1 Mali data. Model predictions were tested against 3 subsets of the Uganda dataset: dataset 1, the full 4-year longitudinal cohort; dataset 2, from districts not used to parameterize matrix C; dataset 3, cross-sectional data, and dataset 4, from Mali as an independent dataset. RESULTS: The model parameterized using matrices A, B and D predicted similar infection dynamics (overall and when stratified by infection intensity). Matrices A-D successfully predicted prevalence in each follow-up year for low and high intensity categories in dataset 1 followed by dataset 2. Matrices A, B and D yielded similar and close matches to dataset 1 with marginal discrepancies when comparing model outputs against datasets 2 and 3. Matrix C produced more variable results, correctly estimating fewer data points. CONCLUSION: Model outputs closely matched observed values and were a useful predictor of the infection dynamics of S. mansoni when using longitudinal and cross-sectional data from Uganda. This also held when the model was tested with data from

  • JOURNAL ARTICLE
    Montresor A, Deol A, Porta NA, Lethanh N, Jankovic D, Montresor A, Deol A, À Porta N, Lethanh N, Jankovic D, Montresor A, Deol A, à Porta N, Lethanh N, Jankovic D, Montresor A, Deol A, À Porta N, Lethanh N, Jankovic D, Montresor A, Deol A, à Porta N, Lethanh N, Jankovic D, Montresor A, Deol A, à Porta N, Lethanh N, Jankovic Det al., 2016,

    Markov Model Predicts Changes in STH Prevalence during Control Activities Even with a Reduced Amount of Baseline Information

    , PLOS NEGLECTED TROPICAL DISEASES, Vol: 10, Pages: e0004371-e0004371, ISSN: 1935-2735

    BACKGROUND: Estimating the reduction in levels of infection during implementation of soil-transmitted helminth (STH) control programmes is important to measure their performance and to plan interventions. Markov modelling techniques have been used with some success to predict changes in STH prevalence following treatment in Viet Nam. The model is stationary and to date, the prediction has been obtained by calculating the transition probabilities between the different classes of intensity following the first year of drug distribution and assuming that these remain constant in subsequent years. However, to run this model longitudinal parasitological data (including intensity of infection) are required for two consecutive years from at least 200 individuals. Since this amount of data is not often available from STH control programmes, the possible application of the model in control programme is limited. The present study aimed to address this issue by adapting the existing Markov model to allow its application when a more limited amount of data is available and to test the predictive capacities of these simplified models. METHOD: We analysed data from field studies conducted with different combination of three parameters: (i) the frequency of drug administration; (ii) the drug distributed; and (iii) the target treatment population (entire population or school-aged children only). This analysis allowed us to define 10 sets of standard transition probabilities to be used to predict prevalence changes when only baseline data are available (simplified model 1). We also formulated three equations (one for each STH parasite) to calculate the predicted prevalence of the different classes of intensity from the total prevalence. These equations allowed us to design a simplified model (SM2) to obtain predictions when the classes of intensity at baseline were not known. To evaluate the performance of the simplified models, we collected data from the scientific literature on chan

  • JOURNAL ARTICLE
    Ortu G, Assoum M, Wittmann U, Knowles S, Clements M, Ndayishimiye O, Basanez M-G, Lau C, Clements A, Fenwick A, Magalhaes RJS, Ortu G, Assoum M, Wittmann U, Knowles S, Clements M, Ndayishimiye O, Basáñez M-G, Lau C, Clements A, Fenwick A, Magalhaes RJS, Ortu G, Assoum M, Wittmann U, Knowles S, Clements M, Ndayishimiye O, Basáñez MG, Lau C, Clements A, Fenwick A, Magalhaes RJ, Ortu G, Assoum M, Wittmann U, Knowles S, Clements M, Ndayishimiye O, Basáñez M-G, Lau C, Clements A, Fenwick A, Magalhaes RJS, Ortu G, Assoum M, Wittmann U, Knowles S, Clements M, Ndayishimiye O, Basáñez MG, Lau C, Clements A, Fenwick A, Magalhaes RJet al., 2016,

    The impact of an 8-year mass drug administration programme on prevalence, intensity and co-infections of soil-transmitted helminthiases in Burundi

    , PARASITES & VECTORS, Vol: 9, Pages: 513-513, ISSN: 1756-3305

    BACKGROUND: Soil-transmitted helminth (STH) infections are amongst the most prevalent infections in the world. Mass drug administration (MDA) programmes have become the most commonly used national interventions for endemic countries to achieve elimination. This paper aims to describe the effect of an 8-year MDA programme on the prevalence, intensity of infection and co-infection of STH in Burundi from 2007 to 2014 and critically appraise the trajectory towards STH elimination in the country. RESULTS: Annual STH parasitological surveys (specifically, a "pilot study" from 2007 to 2011, an "extension study" from 2008 to 2011, and a "national reassessment" in 2014; n = 27,658 children), showed a significant drop in prevalence of infection with any STH ("pooled STH") between baseline and 2011 in both studies, falling from 32 to 16 % in the pilot study, and from 35 to 16 % in the extension study. Most STH infections were of low intensity according to WHO classification. The national reassessment in 2014 showed that prevalence of pooled STH remained significantly below the prevalence in 2007 in both studies but there was no further decrease in STH prevalence from 2011 levels during this time. Spatial dependence analysis showed that prevalence of Trichuris trichiura and Ascaris lumbricoides had a tendency to cluster over the years, whilst only trends in spatial dependence were evident for hookworm infections. Spatial dependence fluctuated over the course of the programme for Ascaris lumbricoides and Trichuris trichiura. However, spatial trends in spatial dependence were evident in 2010 for Ascaris lumbricoides. Analysis of spatial clustering of intensity of infection and heavy infections revealed that the intensity changed over time for all parasites. Heavy intensity was only evident in Ascaris lumbricoides for 2008 and did not appear in proceeding years and other parasites. CONCLUSIONS: These results demonstra

  • JOURNAL ARTICLE
    Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RM, Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RM, Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RM, Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RM, Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RM, Turner HC, Truscott JE, Fleming FM, Hollingsworth TD, Brooker SJ, Anderson RMet al., 2016,

    Cost-effectiveness of scaling up mass drug administration for the control of soil-transmitted helminths: a comparison of cost function and constant costs analyses

    , LANCET INFECTIOUS DISEASES, Vol: 16, Pages: 838-846, ISSN: 1473-3099

    BACKGROUND: The coverage of mass drug administration (MDA) for neglected tropical diseases, such as the soil-transmitted helminths (STHs), needs to rapidly expand to meet WHO's 2020 targets. We aimed to compare use of a cost function to take into account economies of scale to the standard method of assuming a constant cost per treatment when investigating the cost and cost-effectiveness of scaling up a STH MDA programme targeting Ascaris lumbricoides. METHODS: We fitted a cost function describing how the costs of MDA change with scale to empirical cost data and incorporated it into a STH transmission model. Using this cost function, we investigated the consequences of taking into account economies of scale on the projected cost-effectiveness of STH control, by comparison with the standard method of assuming a constant cost per treatment. The cost function was fitted to economic cost data collected as part of a school-based deworming programme in Uganda using maximum likelihood methods. We used the model to investigate the total reduction in the overall worm burden, the total number of prevalent infection case-years averted, and the total number of heavy infection case-years averted. For each year, we calculated the effectiveness as the difference between the worm burden or number of cases and the number in absence of treatment. FINDINGS: When using the cost function, the cost-effectiveness of STH control markedly increased as the programme was scaled up. By contrast, the standard method (constant cost per treatment) undervalued this and generated misleading conclusions. For example, when scaling up control in the projected district from 10% to 75% coverage of at-risk school-age children, the cost-effectiveness in terms of prevention of heavy burden infections was projected to increase by over 70% when using the cost function, but decrease by 18% when assuming a constant cost per treatment. INTERPRETATION: The current exclusion of economies of scale in most economic

  • JOURNAL ARTICLE
    Chami GF, Fenwick A, Bulte E, Kontoleon AA, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Fenwick A, Bulte E, Kontoleon AA, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Fenwick A, Bulte E, Kontoleon AA, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Fenwick A, Bulte E, Kontoleon AA, Kabatereine NB, Tukahebwa EM, Dunne DW, Chami GF, Fenwick A, Bulte E, Kontoleon AA, Kabatereine NB, Tukahebwa EM, Dunne DWet al., 2015,

    Influence of Schistosoma mansoni and Hookworm Infection Intensities on Anaemia in Ugandan Villages

    , PLOS NEGLECTED TROPICAL DISEASES, Vol: 9, Pages: e0004193-e0004193, ISSN: 1935-2735

    BACKGROUND: The association of anaemia with intestinal schistosomiasis and hookworm infections are poorly explored in populations that are not limited to children or pregnant women. METHODS: We sampled 1,832 individuals aged 5-90 years from 30 communities in Mayuge District, Uganda. Demographic, village, and parasitological data were collected. Infection risk factors were compared in ordinal logistic regressions. Anaemia and infection intensities were analyzed in multilevel models, and population attributable fractions were estimated. FINDINGS: Household and village-level predictors of Schistosoma mansoni and hookworm were opposite in direction or significant for single infections. S. mansoni was found primarily in children, whereas hookworm was prevalent amongst the elderly. Anaemia was more prevalent in individuals with S. mansoni and increased by 2.86 fold (p-value<0.001) with heavy S. mansoni infection intensity. Individuals with heavy hookworm were 1.65 times (p-value = 0.008) more likely to have anaemia than uninfected participants. Amongst individuals with heavy S. mansoni infection intensity, 32.0% (p-value<0.001) of anaemia could be attributed to S. mansoni. For people with heavy hookworm infections, 23.7% (p-value = 0.002) of anaemia could be attributed to hookworm. A greater fraction of anaemia (24.9%, p-value = 0.002) was attributable to heavy hookworm infections in adults (excluding pregnant women) as opposed to heavy hookworm infections in school-aged children and pregnant women (20.2%, p-value = 0.001). CONCLUSION: Community-based surveys captured anaemia in children and adults affected by S. mansoni and hookworm infections. For areas endemic with schistosomiasis or hookworm infections, WHO guidelines should include adults for treatment in helminth control programmes.

  • JOURNAL ARTICLE
    Deol AK, Webster JP, Harrison W, Basanez MG, Walker M, Hollingsworth TD, Montresor A, Fernandes J, Fenwick A, French Met al., 2015,

    Development of a Markov transition probability model to predict changes in schistosomiasis infection following treatment

    , TROPICAL MEDICINE & INTERNATIONAL HEALTH, Vol: 20, Pages: 237-237, ISSN: 1360-2276
  • JOURNAL ARTICLE
    Fenwick A, Fenwick A, Fenwick A, OBE AFet al., 2015,

    Praziquantel: do we need another antischistosoma treatment?

    , FUTURE MEDICINAL CHEMISTRY, Vol: 7, Pages: 677-680, ISSN: 1756-8919
  • JOURNAL ARTICLE
    French MD, Churcher TS, Webster JP, Fleming FM, Fenwick A, Kabatereine NB, Sacko M, Garba A, Toure S, Nyandindi U, Mwansa J, Blair L, Bosque-Oliva E, Basanez M-G, French MD, Churcher TS, Webster JP, Fleming FM, Fenwick A, Kabatereine NB, Sacko M, Garba A, Toure S, Nyandindi U, Mwansa J, Blair L, Bosqué-Oliva E, Basáñez M-G, French MD, Churcher TS, Webster JP, Fleming FM, Fenwick A, Kabatereine NB, Sacko M, Garba A, Toure S, Nyandindi U, Mwansa J, Blair L, Bosqué-Oliva E, Basáñez MG, French MD, Churcher TS, Webster JP, Fleming FM, Fenwick A, Kabatereine NB, Sacko M, Garba A, Toure S, Nyandindi U, Mwansa J, Blair L, Bosqué-Oliva E, Basáñez MG, French MD, Churcher TS, Webster JP, Fleming FM, Fenwick A, Kabatereine NB, Sacko M, Garba A, Toure S, Nyandindi U, Mwansa J, Blair L, Bosqué-Oliva E, Basáñez M-Get al., 2015,

    Estimation of changes in the force of infection for intestinal and urogenital schistosomiasis in countries with schistosomiasis control initiative-assisted programmes

    , PARASITES & VECTORS, Vol: 8, ISSN: 1756-3305

    BACKGROUND: The last decade has seen an expansion of national schistosomiasis control programmes in Africa based on large-scale preventative chemotherapy. In many areas this has resulted in considerable reductions in infection and morbidity levels in treated individuals. In this paper, we quantify changes in the force of infection (FOI), defined here as the per (human) host parasite establishment rate, to ascertain the impact on transmission of some of these programmes under the umbrella of the Schistosomiasis Control Initiative (SCI). METHODS: A previous model for the transmission dynamics of Schistosoma mansoni was adapted here to S. haematobium. These models were fitted to longitudinal cohort (infection intensity) monitoring and evaluation data. Changes in the FOI following up to three annual rounds of praziquantel were estimated for Burkina Faso, Mali, Niger, Tanzania, Uganda, and Zambia in sub-Saharan Africa (SSA) according to country, baseline endemicity and schistosome species. Since schistosomiasis transmission is known to be highly focal, changes in the FOI at a finer geographical scale (that of sentinel site) were also estimated for S. mansoni in Uganda. RESULTS: Substantial and statistically significant reductions in the FOI relative to baseline were recorded in the majority of, but not all, combinations of country, parasite species, and endemicity areas. At the finer geographical scale assessed within Uganda, marked heterogeneity in the magnitude and direction of the relative changes in FOI was observed that would not have been appreciated by a coarser-scale analysis. CONCLUSIONS: Reductions in the rate at which humans acquire schistosomes have been achieved in many areas of SSA countries assisted by the SCI, while challenges in effectively reducing transmission persist in others. Understanding the underlying heterogeneity in the impact and performance of the control intervention at the level of the transmission site will become increasingly important fo

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