Publications
220 results found
Prada JM, Touloupou P, Adriko M, et al., 2018, Understanding the relationship between egg- and antigen-based diagnostics of Schistosoma mansoni infection pre- and post-treatment in Uganda., Parasites & Vectors, Vol: 11, ISSN: 1756-3305
BACKGROUND: Schistosomiasis is a major socio-economic and public health problem in many sub-Saharan African countries. After large mass drug administration (MDA) campaigns, prevalence of infection rapidly returns to pre-treatment levels. The traditional egg-based diagnostic for schistosome infections, Kato-Katz, is being substituted in many settings by circulating antigen recognition-based diagnostics, usually the point-of-care circulating cathodic antigen test (CCA). The relationship between these diagnostics is poorly understood, particularly after treatment in both drug-efficacy studies and routine monitoring. RESULTS: We created a model of schistosome infections to better understand and quantify the relationship between these two egg- and adult worm antigen-based diagnostics. We focused particularly on the interpretation of "trace" results after CCA testing. Our analyses suggest that CCA is generally a better predictor of prevalence, particularly after treatment, and that trace CCA results are typically associated with truly infected individuals. CONCLUSIONS: Even though prevalence rises to pre-treatment levels only six months after MDAs, our model suggests that the average intensity of infection is much lower, and is probably in part due to a small burden of surviving juveniles from when the treatment occurred. This work helps to better understand CCA diagnostics and the interpretation of post-treatment prevalence estimations.
Pinsent A, Bailey R, Solomon A, et al., 2018, UNDERSTANDING AND QUANTIFYING THE COMPLEX RELATIONSHIP BETWEEN DIFFERENT DIAGNOSTIC INDICATORS FOR TRACHOMA SURVEILLANCE, 67th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTHM), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 436-437, ISSN: 0002-9637
Pinsent A, Bailey R, Hollingsworth D, 2018, UNDERSTANDING TRACHOMA TRANSMISSION DYNAMICS AT LOW PREVALENCE LEVELS: THE TIMESCALES OF INFECTION AND DISEASE PROVIDE DIFFERENT SIGNALS BEFORE AND AFTER HAULTING INTERVENTIONS, 67th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTHM), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 377-377, ISSN: 0002-9637
Davis E, Minetti C, Reimer L, et al., 2018, PARITY, PRESENCE, AND PREVALENCE: USING MOSQUITO DATA AND GONOTROPHIC CYCLE DYNAMICS TO MONITOR DISEASE IN ELIMINATION-TARGETED SETTINGS, 67th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTHM), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 280-280, ISSN: 0002-9637
Davis E, Prada J, Gunaratna I, et al., 2018, POST-ELIMINATION SURVEILLANCE OF LYMPHATIC FILARIASIS IN SRI LANKA: CAN SEX- AND AGE-STRATIFIED CASE DATA BE USED TO DEMONSTRATE TRANSMISSION INTERRUPTION?, 67th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTHM), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 610-611, ISSN: 0002-9637
Bundy DAP, Appleby LJ, Bradley M, et al., 2018, 100 Years of Mass Deworming Programmes: A Policy Perspective From the World Bank's <i>Disease Control Priorities Analyses</i>, ADVANCES IN PARASITOLOGY, VOL 100, Editors: Rollinson, Stothard, Publisher: ELSEVIER ACADEMIC PRESS INC, Pages: 127-154
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- Citations: 16
Jervis S, Chapman LAC, Dwivedi S, et al., 2017, Variations in visceral leishmaniasis burden, mortality and the pathway to care within Bihar, India, Parasites & Vectors, Vol: 10, ISSN: 1756-3305
BACKGROUND: Visceral leishmaniasis (VL) has been targeted by the WHO for elimination as a public health problem (< 1 case/10,000 people/year) in the Indian sub-continent (ISC) by 2020. Bihar State in India, which accounts for the majority of cases in the ISC, remains a major target for this elimination effort. However, there is considerable spatial, temporal and sub-population variation in occurrence of the disease and the pathway to care, which is largely unexplored and a threat to achieving the target. METHODS: Data from 6081 suspected VL patients who reported being clinically diagnosed during 2012-2013 across eight districts in Bihar were analysed. Graphical comparisons and Chi-square tests were used to determine differences in the burden of identified cases by season, district, age and sex. Log-linear regression models were fitted to onset (of symptoms)-to-diagnosis and onset-to-treatment waiting times to estimate their associations with age, sex, district and various socio-economic factors (SEFs). Logistic regression models were used to identify factors associated with mortality. RESULTS: Comparisons of VL caseloads suggested an annual cycle peaking in January-March. A 17-fold variation in the burden of identified cases across districts and under-representation of young children (0-5 years) relative to age-specific populations in Bihar were observed. Women accounted for a significantly lower proportion of the reported cases than men (41 vs 59%, P < 0.0001). Age, district of residence, house wall materials, caste, treatment cost, travelling for diagnosis and the number of treatments for symptoms before diagnosis were identified as correlates of waiting times. Mortality was associated with age, district of residence, onset-to-treatment waiting time, treatment duration, cattle ownership and cost of diagnosis. CONCLUSIONS: The distribution of VL in Bihar is highly heterogeneous, and reported caseloads and associated mortality vary significa
Bundy DAP, De Silva N, Horton S, et al., 2017, Investment in child and adolescent health and development: key messages from Disease Control Priorities, 3rd Edition, The Lancet, ISSN: 0140-6736
The realisation of human potential for development requires age-specific investment throughout the 8000 days of childhood and adolescence. Focus on the first 1000 days is an essential but insufficient investment. Intervention is also required in three later phases: the middle childhood growth and consolidation phase (5–9 years), when infection and malnutrition constrain growth, and mortality is higher than previously recognised; the adolescent growth spurt (10–14 years), when substantial changes place commensurate demands on good diet and health; and the adolescent phase of growth and consolidation (15–19 years), when new responses are needed to support brain maturation, intense social engagement, and emotional control. Two cost-efficient packages, one delivered through schools and one focusing on later adolescence, would provide phase-specific support across the life cycle, securing the gains of investment in the first 1000 days, enabling substantial catch-up from early growth failure, and leveraging improved learning from concomitant education investments.
Davis EL, Hollingsworth D, Danon L, et al., 2017, IS THERE EVIDENCE THAT THE SEASONAL TIMING OF MASS DE-WORMING FOR ASCARIS IS IMPORTANT?, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 540-541, ISSN: 0002-9637
Dyson L, Crooks O, Bishop A, et al., 2017, HOUSEHOLD MODELLING OF YAWS DATA INDICATES THAT TARGETING TREATMENT USING CASE FINDING AND CONTACT TRACING MAY BE UNSUCCESSFUL AT ERADICATING THE DISEASE, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 407-407, ISSN: 0002-9637
Irvine MA, Kazura JW, Hollingsworth D, et al., 2017, MOSQUITO BITE HETEROGENEITY INFLUENCES LYMPHATIC FILARIASIS PREVALENCE, INTENSITY AND OPPORTUNITIES FOR CONTROL, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 346-346, ISSN: 0002-9637
Chapman L, Chowdhury R, Bern C, et al., 2017, VISCERAL LEISHMANIASIS IN THE INDIAN SUBCONTINENT: HOW MUCH DO ASYMPTOMATICS CONTRIBUTE TO TRANSMISSION AND HOW DOES TRANSMISSION DECREASE WITH DISTANCE FROM A CASE?, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 207-207, ISSN: 0002-9637
Pinsent A, Qureshi U, Donnelly C, et al., 2017, THE INCUBATION PERIOD OF MALARIA AMONGST TRAVELERS RETURNING TO THE UK, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 311-311, ISSN: 0002-9637
Le Rutte E, Chapman LA, Coffeng LE, et al., 2017, DEFINITIONS AND FEASIBILITY OF ELIMINATION OF VISCERAL LEISHMANIASIS, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 207-207, ISSN: 0002-9637
Le Rutte EA, Chapman LAC, Coffeng LE, et al., 2017, Elimination of visceral leishmaniasis on the Indian subcontinent: a comparison of multiple transmission models, 10th European Congress on Tropical Medicine and International Health, Publisher: Wiley, Pages: 68-69, ISSN: 1360-2276
Steinmann P, Reed SG, Mirza F, et al., 2017, Innovative tools and approaches to end the transmission of <i>Mycobacterium leprae</i>, LANCET INFECTIOUS DISEASES, Vol: 17, Pages: E298-E305, ISSN: 1473-3099
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- Citations: 34
Baggaley RF, Irvine MA, Leber W, et al., 2017, Cost-effectiveness of screening for HIV in primary care: a health economics modelling analysis, Lancet HIV, Vol: 4, Pages: E465-E474, ISSN: 2405-4704
BackgroundEarly HIV diagnosis reduces morbidity, mortality, the probability of onward transmission, and their associated costs, but might increase cost because of earlier initiation of antiretroviral treatment (ART). We investigated this trade-off by estimating the cost-effectiveness of HIV screening in primary care.MethodsWe modelled the effect of the four-times higher diagnosis rate observed in the intervention arm of the RHIVA2 randomised controlled trial done in Hackney, London (UK), a borough with high HIV prevalence (≥0·2% adult prevalence). We constructed a dynamic, compartmental model representing incidence of infection and the effect of screening for HIV in general practices in Hackney. We assessed cost-effectiveness of the RHIVA2 trial by fitting model diagnosis rates to the trial data, parameterising with epidemiological and behavioural data from the literature when required, using trial testing costs and projecting future costs of treatment.FindingsOver a 40 year time horizon, incremental cost-effectiveness ratios were £22 201 (95% credible interval 12 662–132 452) per quality-adjusted life-year (QALY) gained, £372 207 (268 162–1 903 385) per death averted, and £628 874 (434 902–4 740 724) per HIV transmission averted. Under this model scenario, with UK cost data, RHIVA2 would reach the upper National Institute for Health and Care Excellence cost-effectiveness threshold (about £30 000 per QALY gained) after 33 years. Scenarios using cost data from Canada (which indicate prolonged and even higher health-care costs for patients diagnosed late) suggest this threshold could be reached in as little as 13 years.InterpretationScreening for HIV in primary care has important public health benefits as well as clinical benefits. We predict it to be cost-effective in the UK in the medium term. However, this intervention might be cost-effective far sooner, and even cost-saving, in settings where long-term health-car
Le Rutte EA, Chapman LAC, Coffeng LE, et al., 2017, Elimination of visceral leishmaniasis in the Indian subcontinent: a comparison of predictions from three transmission models, Epidemics, Vol: 18, Pages: 67-80, ISSN: 1755-4365
We present three transmission models of visceral leishmaniasis (VL) in the Indian subcontinent (ISC) with structural differences regarding the disease stage that provides the main contribution to transmission, including models with a prominent role of asymptomatic infection, and fit them to recent case data from 8 endemic districts in Bihar, India. Following a geographical cross-validation of the models, we compare their predictions for achieving the WHO VL elimination targets with ongoing treatment and vector control strategies. All the transmission models suggest that the WHO elimination target (<1 new VL case per 10,000 capita per year at sub-district level) is likely to be met in Bihar, India, before or close to 2020 in sub-districts with a pre-control incidence of 10 VL cases per 10,000 people per year or less, when current intervention levels (60% coverage of indoor residual spraying (IRS) of insecticide and a delay of 40 days from onset of symptoms to treatment (OT)) are maintained, given the accuracy and generalizability of the existing data regarding incidence and IRS coverage. In settings with a pre-control endemicity level of 5/10,000, increasing the effective IRS coverage from 60 to 80% is predicted to lead to elimination of VL 1–3 years earlier (depending on the particular model), and decreasing OT from 40 to 20 days to bring elimination forward by approximately 1 year. However, in all instances the models suggest that L. donovani transmission will continue after 2020 and thus that surveillance and control measures need to remain in place until the longer-term aim of breaking transmission is achieved.
Hollingsworth TD, Medley GF, 2017, Learning from multi-model comparisons: Collaboration leads to insights, but limitations remain, Epidemics, Vol: 18, Pages: 1-3, ISSN: 1755-4365
Smith ME, Singh BK, Irvine MA, et al., 2017, Predicting lymphatic filariasis transmission and elimination dynamics using a multi-model ensemble framework, Epidemics, Vol: 18, Pages: 16-28, ISSN: 1755-4365
Mathematical models of parasite transmission provide powerful tools for assessing the impacts of interventions. Owing to complexity and uncertainty, no single model may capture all features of transmission and elimination dynamics. Multi-model ensemble modelling offers a framework to help overcome biases of single models. We report on the development of a first multi-model ensemble of three lymphatic filariasis (LF) models (EPIFIL, LYMFASIM, and TRANSFIL), and evaluate its predictive performance in comparison with that of the constituents using calibration and validation data from three case study sites, one each from the three major LF endemic regions: Africa, Southeast Asia and Papua New Guinea (PNG). We assessed the performance of the respective models for predicting the outcomes of annual MDA strategies for various baseline scenarios thought to exemplify the current endemic conditions in the three regions. The results show that the constructed multi-model ensemble outperformed the single models when evaluated across all sites. Single models that best fitted calibration data tended to do less well in simulating the out-of-sample, or validation, intervention data. Scenario modelling results demonstrate that the multi-model ensemble is able to compensate for variance between single models in order to produce more plausible predictions of intervention impacts. Our results highlight the value of an ensemble approach to modelling parasite control dynamics. However, its optimal use will require further methodological improvements as well as consideration of the organizational mechanisms required to ensure that modelling results and data are shared effectively between all stakeholders.
Dyson L, Stolk WA, Farrell SH, et al., 2017, Measuring and modelling the effects of systematic non-adherence to mass drug administration, Epidemics, Vol: 18, Pages: 56-66, ISSN: 1755-4365
It is well understood that the success or failure of a mass drug administration campaign critically depends on the level of coverage achieved. To that end coverage levels are often closely scrutinised during campaigns and the response to underperforming campaigns is to attempt to improve coverage. Modelling work has indicated, however, that the quality of the coverage achieved may also have a significant impact on the outcome. If the coverage achieved is likely to miss similar people every round then this can have a serious detrimental effect on the campaign outcome. We begin by reviewing the current modelling descriptions of this effect and introduce a new modelling framework that can be used to simulate a given level of systematic non-adherence. We formalise the likelihood that people may miss several rounds of treatment using the correlation in the attendance of different rounds. Using two very simplified models of the infection of helminths and non-helminths, respectively, we demonstrate that the modelling description used and the correlation included between treatment rounds can have a profound effect on the time to elimination of disease in a population. It is therefore clear that more detailed coverage data is required to accurately predict the time to disease elimination. We review published coverage data in which individuals are asked how many previous rounds they have attended, and show how this information may be used to assess the level of systematic non-adherence. We note that while the coverages in the data found range from 40.5% to 95.5%, still the correlations found lie in a fairly narrow range (between 0.2806 and 0.5351). This indicates that the level of systematic non-adherence may be similar even in data from different years, countries, diseases and administered drugs.
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).
Irvine MA, Hollingsworth TD, 2017, Making Transmission Models Accessible to End-Users: The Example of TRANSFIL, PLoS Neglected Tropical Diseases, Vol: 11, ISSN: 1935-2727
Koukounari A, Hollingsworth TD, 2017, A strengthening evidence-base for mass deworming, but questions remain, LANCET, Vol: 389, Pages: 231-233, ISSN: 0140-6736
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- Citations: 2
Le Rutte EA, Chapman LA, Coffeng LE, et al., 2017, POLICY RECOMMENDATIONS FOR REACHING ELIMINATION OF VISCERAL LEISHMANIASIS ON THE INDIAN SUBCONTINENT: A COMPARISON OF MULTIPLE TRANSMISSION MODELS, 66th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 601-601, ISSN: 0002-9637
Prada JM, Lamberton PH, Adriko M, et al., 2017, TREATMENT EFFECTS ON EGG AND ANTIGEN DIAGNOSTICS OF <i>SCHISTOSOMA MANSONI</i> INFECTIONS, 66th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 233-234, ISSN: 0002-9637
Bundy DAP, Appleby LJ, Bradley M, et al., 2017, Mass Deworming Programs in Middle Childhood and Adolescence
The current debate on deworming presents an interesting public health paradox. Self-treatment for intestinal worm infection is among the most common self-administered public health interventions, and the delivery of donated drugs through mass drug administration (MDA) programs for soil-transmitted helminths (STHs) exceeds 1 billion doses annually. The clinical literature, especially the older historical work, shows significant impacts of intense STH infection on health; a burgeoning economics literature shows the long-run consequences for development (see, for example, chapter 29 in this volume, Ahuja and others 2017; Fitzpatrick and others 2017). Yet, the literature on clinical trials shows conflicting results, and the resulting controversy has been characterized as the worm wars. The two previous editions of Disease Control Priorities contain chapters on STH and deworming programs (Hotez and others 2006; Warren and others 1993). Much of the biological and clinical understanding reflected in those chapters remains largely unchanged. This chapter presents current estimates of the numbers infected and the disease burden attributable to STH infections to illuminate current program efforts, advances in the understanding of epidemiology and program design, and the controversy regarding the measurement of impact. Definitions of age groupings and age-specific terminology used in this volume can be found in chapter 1 (Bundy, de Silva, and others 2017).
Davis EL, Hollingsworth D, 2017, SEASONAL INFLUENCERS FOR <i>ASCARIS</i> TRANSMISSION: WHAT COULD THEY MEAN FOR PUBLIC HEALTH PROGRAMS AND THE 2020 GOALS?, 66th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 566-566, ISSN: 0002-9637
Prada JM, Reimer LJ, Hollingsworth D, 2017, ALL FOR ONE, ONE FOR ALL: ACROSS BORDER LYMPHATIC FILARIASIS TRANSMISSION CAN COMPROMISE NATIONAL ELIMINATION PROGRAMS IN SOME SETTINGS, 66th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 562-562, ISSN: 0002-9637
Davis EL, Hollingsworth D, Keeling MJ, 2017, MODELLING THE ROLE OF LONG LASTING INSECTICIDE-TREATED BEDNETS IN THE REDUCTION OF LYMPHATIC FILARIASIS PREVALENCE ACROSS A RANGE OF SETTINGS, 66th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 197-197, ISSN: 0002-9637
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