Publications
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Anderson R, Farrell S, Turner H, et al., 2017, Assessing the interruption of the transmission of human helminths with mass drug administration alone: optimizing the design of cluster randomized trials, PARASITES & VECTORS, Vol: 10, ISSN: 1756-3305
Background:A method is outlined for the use of an individual-based stochastic model of parasite transmission dynamics to assess different designs for a cluster randomized trial in which mass drug administration (MDA) is employed in attempts to eliminate the transmission of soil-transmitted helminths (STH) in defined geographic locations. The hypothesis to be tested is: Can MDA alone interrupt the transmission of STH species in defined settings? Clustering is at a village level and the choice of clusters of villages is stratified by transmission intensity (low, medium and high) and parasite species mix (either Ascaris, Trichuris or hookworm dominant).Results:The methodological approach first uses an age-structured deterministic model to predict the MDA coverage required for treating pre-school aged children (Pre-SAC), school aged children (SAC) and adults (Adults) to eliminate transmission (crossing the breakpoint in transmission created by sexual mating in dioecious helminths) with 3 rounds of annual MDA. Stochastic individual-based models are then used to calculate the positive and negative predictive values (PPV and NPV, respectively, for observing elimination or the bounce back of infection) for a defined prevalence of infection 2 years post the cessation of MDA. For the arm only involving the treatment of Pre-SAC and SAC, the failure rate is predicted to be very high (particularly for hookworm-infected villages) unless transmission intensity is very low (R0, or the effective reproductive number R, just above unity in value).Conclusions:The calculations are designed to consider various trial arms and stratifications; namely, community-based treatment and Pre-SAC and SAC only treatment (the two arms of the trial), different STH transmission settings of low, medium and high, and different STH species mixes. Results are considered in the light of the complications introduced by the choice of statistic to define success or failure, varying adherence to treatment, mig
Turner HC, Bettis AA, Dunn JC, et al., 2017, Economic Considerations for Moving beyond the Kato-Katz Technique for Diagnosing Intestinal Parasites As We Move Towards Elimination, TRENDS IN PARASITOLOGY, Vol: 33, Pages: 435-443, ISSN: 1471-4922
While the need for more sensitive diagnostics for intestinal helminths is well known, the cost of developing and implementing new tests is considered relatively high compared to the Kato-Katz technique. Here, we review the reported costs of performing the Kato-Katz technique. We also outline several economic arguments we believe highlight the need for further investment in alternative diagnostics, and considerations that should be made when comparing their costs. In our opinion, we highlight that, without new diagnostic methods, it will be difficult for policy makers to make the most cost-effective decisions and that the potentially higher unit costs of new methods can be outweighed by the long-term programmatic benefits they have (such as the ability to detect the interruption of transmission).
Brisson M, Benard E, Drolet M, et al., 2016, Population-level impact, herd immunity, and eliminationafter human papillomavirus vaccination: a systematicreview and meta-analysis of predictions fromtransmission-dynamic models, Lancet Public Health, Vol: 1, Pages: e8-e17, ISSN: 2468-2667
BackgroundModelling studies have been widely used to inform human papillomavirus (HPV) vaccination policy decisions; however, many models exist and it is not known whether they produce consistent predictions of population-level effectiveness and herd effects. We did a systematic review and meta-analysis of model predictions of the long-term population-level effectiveness of vaccination against HPV 16, 18, 6, and 11 infection in women and men, to examine the variability in predicted herd effects, incremental benefit of vaccinating boys, and potential for HPV-vaccine-type elimination.MethodsWe searched MEDLINE and Embase for transmission-dynamic modelling studies published between Jan 1, 2009, and April 28, 2015, that predicted the population-level impact of vaccination on HPV 6, 11, 16, and 18 infections in high-income countries. We contacted authors to determine whether they were willing to produce new predictions for standardised scenarios. Strategies investigated were girls-only vaccination and girls and boys vaccination at age 12 years. Base-case vaccine characteristics were 100% efficacy and lifetime protection. We did sensitivity analyses by varying vaccination coverage, vaccine efficacy, and duration of protection. For all scenarios we pooled model predictions of relative reductions in HPV prevalence (RRprev) over time after vaccination and summarised results using the median and 10th and 90th percentiles (80% uncertainty intervals [UI]).Findings16 of 19 eligible models from ten high-income countries provided predictions. Under base-case assumptions, 40% vaccination coverage and girls-only vaccination, the RRprev of HPV 16 among women and men was 0·53 (80% UI 0·46–0·68) and 0·36 (0·28–0·61), respectively, after 70 years. With 80% girls-only vaccination coverage, the RRprev of HPV 16 among women and men was 0·93 (0·90–1·00) and 0·83 (0·75–1·00), respectiv
Basanez MG, Walker M, Turner HC, et al., 2016, River Blindness: Mathematical Models for Control and Elimination, ADVANCES IN PARASITOLOGY, VOL 94: MATHEMATICAL MODELS FOR NEGLECTED TROPICAL DISEASES: ESSENTIAL TOOLS FOR CONTROL AND ELIMINATION, PT B, Vol: 94, Pages: 247-341, ISSN: 0065-308X
Truscott JE, Turner HC, Farrell SH, et al., 2016, Soil-Transmitted Helminths: Mathematical Models of Transmission, the Impact of Mass Drug Administration and Transmission Elimination Criteria, ADVANCES IN PARASITOLOGY, VOL 94: MATHEMATICAL MODELS FOR NEGLECTED TROPICAL DISEASES: ESSENTIAL TOOLS FOR CONTROL AND ELIMINATION, PT B, Vol: 94, Pages: 133-198, ISSN: 0065-308X
Turner HC, Bettis AA, Chu BK, et al., 2016, The health and economic benefits of the global programme to eliminate lymphatic filariasis (2000-2014), INFECTIOUS DISEASES OF POVERTY, Vol: 5, ISSN: 2095-5162
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Turner HC, Truscott JE, Bettis AA, et al., 2016, Analysis of the population-level impact of co-administering ivermectin with albendazole or mebendazole for the control and elimination of Trichuris trichiura, Parasite Epidemiology and Control, Vol: 1, Pages: 177-187, ISSN: 2405-6731
INTRODUCTION: Soil-transmitted helminth (STH) infections are predominately controlled by providing children with preventive chemotherapy with either albendazole or mebendazole. However, neither has a high efficacy against Trichuris trichiura. This low efficacy limits the overall effectiveness of the current STH control programmes against T. trichiura. It has been demonstrated that co-administering ivermectin with albendazole or mebendazole significantly increases the efficacy of current treatments, which may increase the overall effectiveness of control programmes. METHODS: Using a STH transmission mathematical model, we evaluated the potential impact of co-administering ivermectin with albendazole or mebendazole to treat T. trichiura within a preventive chemotherapy programme targeting children (2-15 year olds). We evaluated the impact in terms of reduction in prevalent infections, mean worm burden, and prevalence of heavy infections. RESULTS: Although the current treatment strategy reduced T. trichiura worm burden and prevalence of heavy infections, due to their poor efficacy the long term impact of preventive chemotherapy for children was smaller compared to the other STH. Co-administering ivermectin increased the projected impact of the preventive chemotherapy programme in terms of all three of the explored metrics, practically in high transmission settings. Furthermore, ivermectin co-administration greatly increased the feasibility of and timeframe for breaking transmission. CONCLUSIONS: Co-administering ivermectin notably increased the projected impact of preventive chemotherapy in high transmission settings and increased the feasibility for breaking transmission. This has important implications for control programmes, some of which may be shifting focus from morbidity control to interruption of transmission, and some of which may be logistically unable to provide preventive chemotherapy twice a year as recommended. However, the benefit of co-administerin
Turner HC, Truscott JE, Anderson RM, 2016, Cost-effectiveness of community-wide treatment for helminthiasis, Lancet Global Health, Vol: 4, Pages: E156-E156, ISSN: 2214-109X
Turner HC, Truscott JE, Fleming FM, et 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
Dunn JC, Turner HC, Tun A, et al., 2016, Epidemiological surveys of, and research on, soil-transmitted helminths in Southeast Asia: a systematic review, Parasites & Vectors, Vol: 9, ISSN: 1756-3305
Soil-transmitted helminth (STH) infections of humans fall within the World Health Organization’s (WHO) grouping termed the neglected tropical diseases (NTDs). It is estimated that they affect approximately 1.4 billion people worldwide. A significant proportion of these infections are in the population of Southeast Asia. This review analyses published data on STH prevalence and intensity in Southeast Asia over the time period of 1900 to the present to describe age related patterns in these epidemiological measures. This is with a focus on the four major parasite species affecting humans; namely Ascaris lumbricoides, Trichuris trichiura and the hookworms; Necator americanus and Ancylostoma duodenale. Data were also collected on the diagnostic methods used in the published surveys and how the studies were designed to facilitate comparative analyses of recorded patterns and changes therein over time. PubMed, Google Scholar, EMBASE, ISI Web of Science, Cochrane Database of Systematic Reviews and the Global Atlas of Helminth Infections search engines were used to identify studies on STH in Southeast Asia with the search based on the major key words, and variants on, “soil-transmitted helminth” “Ascaris” “Trichuris” “hookworm” and the country name. A total of 280 studies satisfied the inclusion criteria from 11 Southeast Asian countries; Brunei, Cambodia, Indonesia, Lao People’s Democratic Republic (Lao PDR), Malaysia, Myanmar, Philippines, Singapore, Thailand, Timor-Leste and Vietnam. It was concluded that the epidemiological patterns of STH infection by age and species mix in Southeast Asia are similar to those reported in other parts of the world. In the published studies there were a large number of different diagnostic methods used with differing sensitivities and specificities, which makes comparison of the results both within and between countries difficult. There is a clear requirement to standardise the m
Shuford KV, Turner HC, Anderson RM, 2016, Compliance with anthelmintic treatment in the neglected tropical diseases control programmes: a systematic review, Parasites & Vectors, Vol: 9, ISSN: 1756-3305
Preventive chemotherapy (PCT) programmes are used to control five of the highest burden neglected tropical diseases (NTDs): soil-transmitted helminth infections (hookworm, ascariasis, and trichuriasis), lymphatic filariasis, schistosomiasis, onchocerciasis, and trachoma. Over the past decade, new resource commitments for the NTDs have enabled such programmes to intensify their control efforts, and for some diseases, to shift from goals of morbidity control to the interruption of transmission and elimination. To successfully eliminate the parasite reservoir, these programmes will undoubtedly require prolonged, high treatment coverage. However, it is important to consider that even when coverage levels reach an acceptable proportion of the target population, there may be a considerable gap between coverage (those who receive the drug) and compliance (those who actually consume the drug)—a topic of fundamental and perhaps underestimated importance. We conducted a systematic review of published literature that investigated compliance to PCT programmes for NTD control and elimination. Databases searched included PubMed/Medline, Web of Knowledge (including Web of Science), OVID, and Scopus. Data were collected on compliance rates, reasons for non-compliance, as well as the heterogeneity of compliance definitions and calculations across programmes and studies. A total of 112 studies were selected for inclusion. The findings of the review revealed substantial heterogeneity across compliance terms and definitions; an imbalance of available studies for particular disease areas and countries; and finally, a lack of longitudinal compliance studies to properly investigate the role of systematic non-compliance. The lack of consistency among reporting of compliance data can result in under- or over-estimating compliance in a population, and therefore has serious implications for setting and reaching elimination targets. Reframing of the guidelines on compliance definitions c
Anderson RM, Turner HC, Farrell SH, et al., 2016, Studies of the Transmission Dynamics, Mathematical Model Development and the Control of Schistosome Parasites by Mass Drug Administration in Human Communities, ADVANCES IN PARASITOLOGY, VOL 94: MATHEMATICAL MODELS FOR NEGLECTED TROPICAL DISEASES: ESSENTIAL TOOLS FOR CONTROL AND ELIMINATION, PT B, Editors: Basanez, Anderson, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 199-246
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Medley GF, Turner HC, Baggaley RF, et al., 2016, The Role of More Sensitive Helminth Diagnostics in Mass Drug Administration Campaigns: Elimination and Health Impacts, ADVANCES IN PARASITOLOGY, VOL 94: MATHEMATICAL MODELS FOR NEGLECTED TROPICAL DISEASES: ESSENTIAL TOOLS FOR CONTROL AND ELIMINATION, PT B, Editors: Basanez, Anderson, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 343-392
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Turner HC, Truscott JE, Bettis AA, et al., 2015, An economic evaluation of expanding hookworm control strategies to target the whole community., Parasites & Vectors, Vol: 8, ISSN: 1756-3305
BACKGROUND: The WHO treatment guidelines for the soil-transmitted helminths (STH) focus on targeting children for the control of morbidity induced by heavy infections. However, unlike the other STHs, the majority of hookworm infections are harboured by adults. This untreated burden may have important implications for controlling both hookworm's morbidity and transmission. This is particularly significant in the context of the increased interest in investigating STH elimination strategies. METHODS: We used a deterministic STH transmission model and parameter estimates derived from field epidemiological studies to evaluate the impact of child-targeted (2-14 year olds) versus community-wide treatment against hookworm in terms of preventing morbidity and the timeframe for breaking transmission. Furthermore, we investigated how mass treatment may influence the long-term programmatic costs of preventive chemotherapy for hookworm. RESULTS: The model projected that a large proportion of the overall morbidity due to hookworm was unaffected by the current child-targeted strategy. Furthermore, driving worm burdens to levels low enough to potentially break transmission was only possible when using community-wide treatment. Due to these projected reductions in programme duration, it was possible for community-wide treatment to generate cost savings - even if it notably increases the annual distribution costs. CONCLUSIONS: Community-wide treatment is notably more cost-effective for controlling hookworm's morbidity and transmission than the current child-targeted strategies and could even be cost-saving in many settings in the longer term. These calculations suggest that it is not optimum to treat using the same treatment strategies as other STH. Hookworm morbidity and transmission control require community-wide treatment.
Anderson RM, Turner HC, Farrell SH, et al., 2015, What is required in terms of mass drug administration to interrupt the transmission of schistosome parasites in regions of endemic infection?, Parasites & Vectors, Vol: 8, ISSN: 1756-3305
Background: Schistosomiasis is endemic in 54 countries, but has one of the lowest coverages by mass drugadministration of all helminth diseases. However, with increasing drug availability through donation, the WorldHealth Organisation has set a goal of increasing coverage to 75 % of at-risk children in endemic countries andelimination in some regions. In this paper, we assess the impact on schistosomiasis of the WHO goals in terms ofcontrol and elimination.Methods: We use an age-structured deterministic model of schistosome transmission in a human community andthe effect of mass drug administration. The model is fitted to baseline data from a longitudinal re-infection study inKenya and validated against the subsequent re-infection data. We examine the impact on host worm burden of thecurrent treatment trend, extrapolated to meet the WHO goals, and its sensitivity to uncertainty in importantparameters. We assess the feasibility of achieving elimination.Results: Model results show that the current treatment trend, extrapolated to the WHO goals, is able to greatlyreduce host worm burdens. If coverage is continued at the same level beyond 2020, elimination is possible for lowto moderate transmission settings, where transmission intensity is defined by the basic reproduction number, R0.Low levels of adult coverage have a significant impact on worm burden in all settings. Model validation against there-infection survey demonstrates that the age-structured model is able to match post-treatment data well in termsof egg output, but that some details of re-infection among school children and young adults are not currently wellrepresented.Conclusions: Our work suggests that the current WHO treatment goals should be successful in bringing about amajor reduction in schistosome infection in treated communities. If continued over a 15 year period, they are likelyto result in elimination, at least in areas with lower transmission.
Truscott JE, Turner HC, Anderson RM, 2015, What impact will the achievement of the current World Health Organisation targets for anthelmintic treatment coverage in children have on the intensity of soil transmitted helminth infections?, Parasites & Vectors, Vol: 8, ISSN: 1756-3305
BackgroundIt is the aim of the World Health Organisation to eliminate soil-transmitted helminths (STH) as a health problem in children. To this end, the goal is to increase anthelmintic treatment coverage for soil transmitted helminths to reach 75 % in pre-school aged and school aged children by 2020 in endemic countries. In this paper, we use mathematical models to investigate the impact of achieving this goal on the burdens of Ascaris lumbricoides, Trichuris trichuria and hookworm.MethodsWe employ a deterministic fully age-structured model of STH transmission and mass drug administration to examine the changes in worm burden in response to the known and projected coverage trends in children up to 2020 and beyond. Parameters are estimated from worm expulsion data and age intensity profiles before treatment using maximum likelihood methods. Model validation is performed using reinfection studies for Ascaris and analyses are conducted to assess the sensitivity of the predicted outcomes to variation in parameter estimates including transmission intensity (R0), children’s contributions to the pool of infective stages and drug coverage levels.ResultsThe impact of the required increase in coverage trends are quite different across the three species. Ascaris burdens are reduced dramatically by 2020 with elimination predicted within studied the setting a further 10 years. For Trichuris and hookworm, however, impact is more limited, due to issues of drug efficacy (Trichuris) and distribution of worms in the population (hookworm). Sensitivity analysis indicates that results are largely robust. However, validation against Ascaris data indicates that assumptions concerning re-infection among children may have to be revised.ConclusionsThe 2020 coverage target is predicted to have a major impact on Ascaris levels by 2020. However, there is evidence from model validation that Ascaris in children is more resilient to treatment than currently assumed in the model. Broader cov
Brooker SJ, Mwandawiro CS, Halliday KE, et al., 2015, Interrupting transmission of soil-transmitted helminths: a study protocol for cluster randomised trials evaluating alternative treatment strategies and delivery systems in Kenya, BMJ Open, Vol: 5, ISSN: 2044-6055
Introduction In recent years, an unprecedented emphasis has been given to the control of neglected tropical diseases, including soil-transmitted helminths (STHs). The mainstay of STH control is school-based deworming (SBD), but mathematical modelling has shown that in all but very low transmission settings, SBD is unlikely to interrupt transmission, and that new treatment strategies are required. This study seeks to answer the question: is it possible to interrupt the transmission of STH, and, if so, what is the most cost-effective treatment strategy and delivery system to achieve this goal?Methods and analysis Two cluster randomised trials are being implemented in contrasting settings in Kenya. The interventions are annual mass anthelmintic treatment delivered to preschool- and school-aged children, as part of a national SBD programme, or to entire communities, delivered by community health workers. Allocation to study group is by cluster, using predefined units used in public health provision—termed community units (CUs). CUs are randomised to one of three groups: receiving either (1) annual SBD; (2) annual community-based deworming (CBD); or (3) biannual CBD. The primary outcome measure is the prevalence of hookworm infection, assessed by four cross-sectional surveys. Secondary outcomes are prevalence of Ascaris lumbricoides and Trichuris trichiura, intensity of species infections and treatment coverage. Costs and cost-effectiveness will be evaluated. Among a random subsample of participants, worm burden and proportion of unfertilised eggs will be assessed longitudinally. A nested process evaluation, using semistructured interviews, focus group discussions and a stakeholder analysis, will investigate the community acceptability, feasibility and scale-up of each delivery system.
Turner HC, Walker M, Lustigman S, et al., 2015, HUMAN ONCHOCERCIASIS: MODELLING THE POTENTIAL LONG-TERM CONSEQUENCES OF A VACCINATION PROGRAM, Publisher: AMER SOC TROP MED & HYGIENE, Pages: 138-138, ISSN: 0002-9637
Nikolay B, Mwandawiro CS, Kihara JH, et al., 2015, Understanding Heterogeneity in the Impact of National Neglected Tropical Disease Control Programmes: Evidence from School-Based Deworming in Kenya, PLOS Neglected Tropical Diseases, Vol: 9, ISSN: 1935-2735
BackgroundThe implementation of soil-transmitted helminth (STH) treatment programmes occurs invaried environmental, social and economic contexts. Programme impact will be influencedby factors that affect the reduction in the prevalence and intensity of infections followingtreatment, as well as the subsequent rate of reinfection. To better understand the heterogeneityof programme impact and its underlying reasons, we investigated the influence of contextualfactors on reduction in STH infection as part of the national school based deworming(SBD) programme in Kenya.Materials and MethodsData on the prevalence and intensity of infection were collected within the monitoring andevaluation component of the SBD programme at baseline and after delivery of two annualtreatment rounds in 153 schools in western Kenya. Using a framework that considers STHepidemiology and transmission dynamics, capacity to deliver treatment, operational feasibilityand financial capacity, data were assembled at both school and district (county) levels.Geographic heterogeneity of programme impact was assessed by descriptive and spatialanalyses. Factors associated with absolute reductions of Ascaris lumbricoides and hookworm infection prevalence and intensity were identified using mixed effects linearregression modelling adjusting for baseline infection levels.Principal FindingsThe reduction in prevalence and intensity of A. lumbricoides and hookworms varied significantlyby county and within counties by school. Multivariable analysis of factors associatedwith programme impact showed that absolute A. lumbricoides reductions varied by environmentalconditions and access to improved sanitation at schools or within the community.Larger reduction in prevalence and intensity of hookworms were found in schools locatedwithin areas with higher community level access to improved sanitation and within countieswith higher economic and health service delivery indicator scores.ConclusionsThe study identifies factors
Anderson RM, Turner HC, Truscott JE, et al., 2015, Should the Goal for the Treatment of Soil Transmitted Helminth (STH) Infections Be Changed from Morbidity Control in Children to Community-Wide Transmission Elimination?, PLOS Neglected Tropical Diseases, Vol: 9, Pages: e0003897-e0003897, ISSN: 1935-2735
Basanez MG, Turner HC, Walker M, et al., 2015, Human Onchocerciasis: Modelling the Potential Long-term Consequences of a Vaccination Programme, PLOS Neglected Tropical Diseases, Vol: 9, ISSN: 1935-2735
BackgroundCurrently, the predominant onchocerciasis control strategy in Africa is annual mass drugadministration (MDA) with ivermectin. However, there is a consensus among the globalhealth community, supported by mathematical modelling, that onchocerciasis in Africa willnot be eliminated within proposed time frameworks in all endemic foci with only annualMDA, and novel and alternative strategies are urgently needed. Furthermore, use of MDAwith ivermectin is already compromised in large areas of central Africa co-endemic with Loaloa, and there are areas where suboptimal or atypical responses to ivermectin have beendocumented. An onchocerciasis vaccine would be highly advantageous in these areas.Methodology/Principal FindingsWe used a previously developed onchocerciasis transmission model (EPIONCHO) toinvestigate the impact of vaccination in areas where loiasis and onchocerciasis are coendemicand ivermectin is contraindicated. We also explore the potential influence of a vaccinationprogramme on infection resurgence in areas where local elimination has been successfullyachieved. Based on the age range included in the Expanded Programme onImmunization (EPI), the vaccine was assumed to target 1 to 5 year olds. Our modellingresults indicate that the deployment of an onchocerciasis vaccine would have a beneficialimpact in onchocerciasis–loiasis co-endemic areas, markedly reducing microfilarial load inthe young (under 20 yr) age groups.Conclusions/SignificanceAn onchocerciasis prophylactic vaccine would reduce the onchocerciasis disease burden inpopulations where ivermectin cannot be administered safely. Moreover, a vaccine could substantially decrease the chance of re-emergence of Onchocerca volvulus infection inareas where it is deemed that MDA with ivermectin can be stopped. Therefore, a vaccinewould protect the substantial investments made by present and past onchocerciasis controlprogrammes, decreasing the chance of disease recrudescence and offering an important
Turner HC, Truscott JE, Hollingsworth TD, et al., 2015, Cost and cost-effectiveness of soil-transmitted helminth treatment programmes: systematic review and research needs., Parasites & Vectors, Vol: 8, ISSN: 1756-3305
BACKGROUND: In this time of rapidly expanding mass drug administration (MDA) coverage and the new commitments for soil-transmitted helminth (STH) control, it is essential that resources are allocated in an efficient manner to have the greatest impact. However, many questions remain regarding how best to deliver STH treatment programmes; these include which age-groups should be targeted and how often. To perform further analyses to investigate what the most cost-effective control strategies are in different settings, accurate cost data for targeting different age groups at different treatment frequencies (in a range of settings) are essential. METHODS: Using the electronic databases PubMed, MEDLINE, and ISI Web of Knowledge, we perform a systematic review of costing studies and cost-effectiveness evaluations for potential STH treatment strategies. We use this review to highlight research gaps and outline the key future research needs. RESULTS: We identified 29 studies reporting costs of STH treatment and 17 studies that investigated its cost-effectiveness. The majority of these pertained to programmes only targeting school-aged children (SAC), with relatively few studies investigating alternative preventive chemotherapy (PCT) treatment strategies. The methods of cost data collection, analysis and reporting were highly variable among the different studies. Only four of the costing studies were found to have high applicability for use in forthcoming economic evaluations. There are also very few studies quantifying the costs of increasing the treatment frequency. CONCLUSIONS: The absence of cost data and inconsistencies in the collection and analysis methods constitutes a major research gap for STH control. Detailed and accurate costs of targeting different age groups or increasing treatment frequency will be essential to formulate cost-effective public health policy. Defining the most cost-effective control strategies in different settings is of high significance durin
Turner HC, Walker M, Attah SK, et al., 2015, The potential impact of moxidectin on onchocerciasis elimination in Africa: an economic evaluation based on the Phase II clinical trial data, Parasites & Vectors, Vol: 8, ISSN: 1756-3305
Turner HC, Walker M, French MD, et al., 2014, Neglected tools for neglected diseases: mathematical models in economic evaluations, TRENDS IN PARASITOLOGY, Vol: 30, Pages: 562-570, ISSN: 1471-4922
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Turner HC, Walker M, Churcher TS, et al., 2014, Reaching the London Declaration on Neglected Tropical Diseases Goals for Onchocerciasis: An Economic Evaluation of Increasing the Frequency of Ivermectin Treatment in Africa, CLINICAL INFECTIOUS DISEASES, Vol: 59, Pages: 923-932, ISSN: 1058-4838
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Turner HC, Walker M, Churcher TS, et al., 2014, Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections, PARASITES & VECTORS, Vol: 7, ISSN: 1756-3305
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Naidoo K, Gichuhi S, Basanez M-G, et al., 2014, Prevalence and causes of vision loss in sub-Saharan Africa: 1990-2010, BRITISH JOURNAL OF OPHTHALMOLOGY, Vol: 98, Pages: 612-618, ISSN: 0007-1161
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Turner HC, Baussano I, Garnett GP, 2013, Vaccinating women previously exposed to human papillomavirus: a cost-effectiveness analysis of the bivalent vaccine, PLoS One, Vol: 8, Pages: 1-9, ISSN: 1932-6203
Recent trials have indicated that women with prior exposure to Human papillomavirus (HPV) subtypes 16/18 receive protection against reinfection from the HPV vaccines. However, many of the original models investigating the cost effectiveness of different vaccination strategies for the protection of cervical cancer assumed, based on the trial results at that time, that these women received no protection. We developed a deterministic, dynamic transmission model that incorporates the vaccine-induced protection of women with prior exposure to HPV. The model was used to estimate the cost effectiveness of progressively extending a vaccination programme using the bivalent vaccine to older age groups both with and without protection of women with prior exposure. We did this under a range of assumptions on the level of natural immunity. Our modelling projections indicate that including the protection of women with prior HPV exposure can have a profound effect on the cost effectiveness of vaccinating adults. The impact of this protection is inversely related to the level of natural immunity. Our results indicate that adult vaccination strategies should potentially be reassessed, and that it is important to include the protection of non-naive women previously infected with HPV in future studies. Furthermore, they also highlight the need for a more thorough investigation of this protection.
Turner HC, Osei-Atweneboana MY, Walker M, et al., 2013, The Cost of Annual versus Biannual Community-Directed Treatment of Onchocerciasis with Ivermectin: Ghana as a Case Study, PLOS NEGLECTED TROPICAL DISEASES, Vol: 7, ISSN: 1935-2735
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Turner HC, Churcher TS, Walker M, et al., 2013, Uncertainty Surrounding Projections of the Long-Term Impact of Ivermectin Treatment on Human Onchocerciasis, PLOS NEGLECTED TROPICAL DISEASES, Vol: 7, ISSN: 1935-2735
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- Citations: 41
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