623 results found
Collyer BS, Truscott JE, Mwandawiro CS, et al., 2023, How important is the spatial movement of people in attempts to eliminate the transmission of human helminth infections by mass drug administration?, Philos Trans R Soc Lond B Biol Sci, Vol: 378
Human mobility contributes to the spatial dynamics of many infectious diseases, and understanding these dynamics helps us to determine the most effective ways to intervene and plan surveillance. In this paper, we describe a novel transmission model for the spatial dynamics of hookworm, a parasitic worm which is a common infection across sub-Saharan Africa, East Asia and the Pacific islands. We fit our model, with and without mobility, to data obtained from a sub-county in Kenya, and validate the model's predictions against the decline in prevalence observed over the course of a clustered randomized control trial evaluating methods of administering mass chemotherapy. We find that our model which incorporates human mobility is able to reproduce the observed patterns in decline of prevalence during the TUMIKIA trial, and additionally, that the widespread bounce-back of infection may be possible over many years, depending on the rates of people movement between villages. The results have important implications for the design of mass chemotherapy programmes for the elimination of human helminth transmission. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
Forbes K, Basáñez M-G, Hollingsworth TD, et al., 2023, Introduction to the special issue: challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs, Philosophical Transactions of the Royal Society B: Biological Sciences, Vol: 378, Pages: 1-8, ISSN: 0962-8436
Twenty neglected tropical diseases (NTDs) are currently prioritised by the World Health Organization for eradication, elimination as a public health problem, elimination of transmission or control by 2030. This issue celebrates progress made since the 2012 London Declaration on NTDs and discusses challenges currently faced to achieve these goals. It comprises 14 contributions spanning NTDs tackled by intensified disease management to those addressed by preventive chemotherapy. Although COVID-19 negatively affected NTD programmes, it also served to spur new multisectoral approaches to strengthen school-based health systems. The issue highlights the needs to improve impact survey design, evaluate new diagnostics, understand the consequences of heterogeneous prevalence and human movement, the potential impact of alternative treatment strategies and the importance of zoonotic transmission. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
Rayment Gomez S, Maddren R, Liyew EF, et al., 2023, Predisposition to soil-transmitted helminth reinfection after four rounds of mass drug administration: results from a longitudinal cohort in the Geshiyaro project, a transmission elimination feasibility study in the Wolaita zone of southern Ethiopia., Trans R Soc Trop Med Hyg, Vol: 117, Pages: 514-521
BACKGROUND: Current WHO strategies for reaching soil-transmitted helminths (STH) elimination as a public health problem excludes treating certain adult populations in endemic areas, creating infection reservoirs that drive 'bounce back' of STH infection to pretreatment levels post-mass drug administration (MDA). Predisposition is a widespread, but poorly understood phenomena among helminth infections where individuals are predisposed to reinfection after repeated treatments. METHODS: This analysis uses Geshiyaro project data, an STH control programme exploring transmission interruption by community-wide MDA and enhanced water, sanitation and hygiene during 2019-2023. Parasitological survey data from longitudinal cohorts are analysed using Kendall's Tau-b rank correlation to assess the evidence for predisposition to light or heavy infection between four consecutive rounds of MDA. RESULTS: Correlation analyses revealed the strongest evidence for predisposition to heavy or light Ascaris lumbricoides infection was between survey 1 and 2 (Tau-b 0.29; p<0.001). Overall patterns were not observed for Trichuris trichiura or hookworm infections, however, some significant and notable correlations were recorded for some stratifications and time points. CONCLUSIONS: Evidence for predisposition in endemic settings in southern Ethiopia with low STH prevalence suggests that more targeted approaches to MDA in those predisposed to infection may be a sensible control strategy if cheap, point of care diagnostics are available.
Maddren R, Phillips A, Rayment Gomez S, et al., 2023, Individual longitudinal compliance to neglected tropical disease mass drug administration programmes, a systematic review., PLoS Negl Trop Dis, Vol: 17
Repeated distribution of preventative chemotherapy (PC) by mass drug administration forms the mainstay of transmission control for five of the 20 recognised neglected tropical diseases (NTDs); soil-transmitted helminths, schistosomiasis, lymphatic filariasis, onchocerciasis and trachoma. The efficiency of such programmes is reliant upon participants swallowing the offered treatment consistently at each round. This is measured by compliance, defined as the proportion of eligible participants swallowing treatment. Individually linked longitudinal compliance data is important for assessing the potential impact of MDA-based control programmes, yet this accurate monitoring is rarely implemented in those for NTDs. Longitudinal compliance data reported by control programmes globally for the five (PC)-NTDs since 2016 is examined, focusing on key associations of compliance with age and gender. PubMed and Web of Science was searched in January 2022 for articles written in English and Spanish, and the subsequent extraction adhered to PRISMA guidelines. Study title screening was aided by Rayyan, a machine learning software package. Studies were considered for inclusion if primary compliance data was recorded for more than one time point, in a population larger than 100 participants. All data analysis was conducted in R. A total of 89 studies were identified containing compliance data, 57 were longitudinal studies, of which 25 reported individually linked data reported by varying methods. The association of increasing age with the degree of systematic treatment was commonly reported. The review is limited by the paucity of data published on this topic. The varying and overlapping terminologies used to describe coverage (receiving treatment) and compliance (swallowing treatment) is reviewed. Consequently, it is recommended that WHO considers clearly defining the terms for coverage, compliance, and longitudinal compliance which are currently contradictory across their NTD treatmen
Hughes A, Ng-Nguyen D, Clarke NE, et al., 2023, Epidemiology of soil-transmitted helminths using quantitative PCR and risk factors for hookworm and Necator americanus infection in school children in Dak Lak province, Vietnam., Parasit Vectors, Vol: 16
BACKGROUND: Soil-transmitted helminth (STH) infection is driven by a complex interaction of demographic, socioeconomic and behavioural factors, including those related to water, sanitation and hygiene (WASH). Epidemiological studies that measure both infection and potential risk factors associated with infection help to understand the drivers of transmission in a population and therefore can provide information to optimise STH control programmes. METHODS: During October and November 2019, we conducted a cross-sectional survey of the prevalence and intensity of STH infection and associated risk factors among 7710 primary-school-age children from 64 primary schools across 13 districts in Dak Lak province, Vietnam. Quantitative PCR (qPCR) was used to detect and quantify STH infections. RESULTS: The predominant STH species was the hookworm Necator americanus (overall cluster-adjusted prevalence of 13.7%), and its prevalence was heterogeneously distributed across surveyed schools (0% to 56.3%). All other STH species had a prevalence of less than 1%. Using mixed-effects logistic regression, we found that the adjusted odds ratio (aOR) was significantly higher for both infection and moderate-to-heavy-intensity infection with N. americanus among children from multiple ethnic minority groups, compared to children from the majority group (Kinh). Adjusted odds of infection with N. americanus were also higher in children who reported practising open defecation at school (aOR 1.42, 95% CI 1.05, 1.93, P = 0.02) and in those who had an unimproved household water supply (aOR 1.28, 95% CI 1.04, 1.57, P = 0.02). Conversely, children with a flushing household toilet had a reduced risk of infection (aOR 0.58, 95% CI 0.47, 0.70, P < 0.01), as did those whose primary female carer attended secondary (aOR 0.65, 95% CI 0.51, 0.84, P < 0.01) or tertiary education (aOR 0.39, 95% CI 0.24, 0.63, P < 0.01). CONCLUSIONS
Maddren R, Phillips A, Ower A, et al., 2023, Correction: Soil-transmitted helminths and schistosome infections in Ethiopia: a systematic review of progress in their control over the past 20 years., Parasit Vectors, Vol: 16
Sheahan W, Anderson R, Aruldas K, et al., 2023, Overestimation of school-based deworming coverage resulting from school-based reporting., PLoS Negl Trop Dis, Vol: 17
BACKGROUND: Soil Transmitted Helminths (STH) infect over 1.5 billion people globally and are associated with anemia and stunting, resulting in an annual toll of 1.9 million Disability-Adjusted Life Years (DALYs). School-based deworming (SBD), via mass drug administration (MDA) campaigns with albendazole or mebendazole, has been recommended by the World Health Organization to reduce levels of morbidity due to STH in endemic areas. DeWorm3 is a cluster-randomized trial, conducted in three study sites in Benin, India, and Malawi, designed to assess the feasibility of interrupting STH transmission with community-wide MDA as a potential strategy to replace SBD. This analysis examines data from the DeWorm3 trial to quantify discrepancies between school-level reporting of SBD and gold standard individual-level survey reporting of SBD. METHODOLOGY/PRINCIPAL FINDINGS: Population-weighted averages of school-level SBD calculated at the cluster level were compared to aggregated individual-level SBD estimates to produce a Mean Squared Error (MSE) estimate for each study site. In order to estimate individual-level SBD coverage, these MSE values were applied to SBD estimates from the control arm of the DeWorm3 trial, where only school-level reporting of SBD coverage had been collected. In each study site, SBD coverage in the school-level datasets was substantially higher than that obtained from individual-level datasets, indicating possible overestimation of school-level SBD coverage. When applying observed MSE to project expected coverages in the control arm, SBD coverage dropped from 89.1% to 70.5% (p-value < 0.001) in Benin, from 97.7% to 84.5% (p-value < 0.001) in India, and from 41.5% to 37.5% (p-value < 0.001) in Malawi. CONCLUSIONS/SIGNIFICANCE: These estimates indicate that school-level SBD reporting is likely to significantly overestimate program coverage. These findings suggest that current SBD coverage estimates derived from school-based program data may substa
Beukenhorst ALL, Koch CMM, Hadjichrysanthou C, et al., 2023, SARS-CoV-2 elicits non-sterilizing immunity and evades vaccine-induced immunity: implications for future vaccination strategies, EUROPEAN JOURNAL OF EPIDEMIOLOGY, ISSN: 0393-2990
Anderson RM, Cano J, Hollinsworth TD, et al., 2022, Responding to the cuts in UK AID to neglected tropical diseases control programmes in Africa, TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE, ISSN: 0035-9203
Phillips AE, Ower AK, Mekete K, et al., 2022, Association between water, sanitation, and hygiene access and the prevalence of soil-transmitted helminth and schistosome infections in Wolayita, Ethiopia., Parasit Vectors, Vol: 15
BACKGROUND: The Geshiyaro project is a 5-year intervention to assess the impact of community- and school-based water, sanitation, and hygiene (WaSH) interventions on reducing infection with soil-transmitted helminths (STH) and schistosome parasites in combination with deworming in Wolayita zone, Ethiopia. METHODS: A population-based, cross-sectional census and parasitological mapping activity was conducted between 2018 and 2019. Individuals in the census were identified using either a registered study ID card or biometric fingerprint to enable linkage of their household WaSH data with baseline STH and schistosome prevalence for risk analysis. RESULTS: Prevalence of STH was 15.5% for any STH species, 9.47% for Ascaris lumbricoides, 1.78% for Trichuris trichiura, and 7.24% for hookworm. Intestinal schistosomiasis (Schistosoma mansoni) infection prevalence was 0.85% by Kato Katz, 21.6% by POC-CCA trace positive (Tr +), and 13.3% trace negative (Tr-). Microhaematuria was 2.77%, with 0.13% of people examined with S. haematobium eggs detected by urine filtration. At the household level, increased (> 30 min) time taken to collect drinking water, sharing a latrine, and lack of handwashing facilities were all associated with a greater risk of A. lumbricoides, hookworm, and S. mansoni infection. Not disposing of infant stool at the household and clothes washing/recreational freshwater contact were significantly associated with higher risk of schistosomiasis infection. Aggregating WaSH data at the community level showed odds of A. lumbricoides, hookworm, and T. trichiura infection were significantly lower as both community sanitation coverage and access to improved drinking water improved. CONCLUSIONS: The principal finding of this study is that lack of access to WaSH, such as improved drinking water and shared toilet and hand-washing facilities, were linked to an increased risk of infection with STH and schistosome parasites. These associations are diffi
Borlase A, Le Rutte EA, Castano S, et al., 2022, Evaluating and mitigating the potential indirect effect of COVID-19 on control programmes for seven neglected tropical diseases: a modelling study, LANCET GLOBAL HEALTH, Vol: 10, Pages: E1600-E1611, ISSN: 2214-109X
Hadjichrysanthou C, Beukenhorst AL, Koch CM, et al., 2022, Exploring the Role of Antiviral Nasal Sprays in the Control of Emerging Respiratory Infections in the Community, INFECTIOUS DISEASES AND THERAPY, Vol: 11, Pages: 2287-2296, ISSN: 2193-8229
Landeryou T, Maddren R, Gomez SR, et al., 2022, Longitudinal monitoring of prevalence and intensity of soil-transmitted helminth infections as part of community-wide mass drug administration within the Geshiyaro project in the Bolosso Sore district, Wolaita, Ethiopia, PLOS NEGLECTED TROPICAL DISEASES, Vol: 16, ISSN: 1935-2735
Chong NS, Hardwick RJ, Smith SR, et al., 2022, A prevalence-based transmission model for the study of the epidemiology and control of soil-transmitted helminthiasis, PLOS ONE, Vol: 17, ISSN: 1932-6203
Kura K, Truscott JE, Collyer BS, et al., 2022, The observed relationship between the degree of parasite aggregation and the prevalence of infection within human host populations for soil-transmitted helminth and schistosome infections, TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE, Vol: 116, Pages: 1226-1229, ISSN: 0035-9203
Kura K, Ayabina D, Hollingsworth TD, et al., 2022, Determining the optimal strategies to achieve elimination of transmission for Schistosoma mansoni, PARASITES & VECTORS, Vol: 15, ISSN: 1756-3305
Landeryou T, Rabone M, Allan FL, et al., 2022, Genome-wide insights into adaptive hybridisation across the Schistosoma haematobium group in West and Central Africa, PLOS NEGLECTED TROPICAL DISEASES, Vol: 16, ISSN: 1935-2735
Mohammed H, Landeryou T, Chernet M, et al., 2022, Comparing the accuracy of two diagnostic methods for detection of light Schistosoma haematobium infection in an elimination setting in Wolaita Zone, South Western Ethiopia., PLoS One, Vol: 17
Reagent urinalysis dipstick and filtration have been recommended diagnostic methods for the detection of urogenital schistosomiasis. However, the accurate diagnosis of light infections using these methods presents a major challenge. This study evaluates the diagnosis accuracy of light infection with Schistosoma haematobium in study participants living in Wolaita Zone, an area targeted for sustainable control of Schistosomiasis, and ultimately interrupt transmission. Urine samples were collected from children and adults in surveys carried out during baseline and longitudinal sentinel site surveys conducted from 2018 to 2020. All urine samples were tested using a reagent urinalysis dipstick test (Haemastix) to detect microhaematuria with reference urine filtration technique as a proxy for S. haematobium infection. Sensitivity and specificity were determined in diagnosing urogenital schistosomiasis. Cohen's Kappa statistics was done for the agreement of these diagnostic methods. A total of 12,102 participants were enrolled in the current baseline study. Among them, 285 (2.35%) samples tested positive for microhaematuria and 21 (0.20%) positive for S. haematobium eggs. A total of 4,357 samples were examined in year 1 and year 2 using urine dipsticks, and urine filtration 172 (3.95%) and 2 (0.05%) were positive for microhaematuria and S. haematobium eggs. The reagent urinalysis dipsticks showed the highest sensitivity and specificity for diagnosing light intensity of infection,100% (95% CI:85.18-100.00) and 97.4% (95% CI: 97.10-97.60), respectively. There is a slight agreement between the two methods (Kappa = 0.09, 95% CI: 0.01-0.18). The present study revealed very low prevalence and light intensity of S. haematobium infections. The study also highlights that the dipstick test is considered a useful adjunct diagnostic tool for population-based control of urogenital schistosomiasis.
Kura K, Hardwick RJ, Truscott JE, et al., 2021, What is the impact of acquired immunity on the transmission of schistosomiasis and the efficacy of current and planned mass drug administration programmes?, PLoS Neglected Tropical Diseases, Vol: 15, Pages: 1-17, ISSN: 1935-2727
Schistosomiasis causes severe morbidity in many countries with endemic infection with the schistosome digenean parasites in Africa and Asia. To control and eliminate the disease resulting from infection, regular mass drug administration (MDA) is used, with a focus on school-aged children (SAC; 5-14 years of age). In some high transmission settings, the World Health Organization (WHO) also recommends the inclusion of at-risk adults in MDA treatment programmes. The question of whether ecology (age-dependant exposure) or immunity (resistance to reinfection), or some combination of both, determines the form of observed convex age-intensity profile is still unresolved, but there is a growing body of evidence that the human hosts acquire some partial level of immunity after a long period of repeated exposure to infection. In the majority of past research modelling schistosome transmission and the impact of MDA programmes, the effect of acquired immunity has not been taken into account. Past work has been based on the assumption that age-related contact rates generate convex horizontal age-intensity profiles. In this paper, we use an individual based stochastic model of transmission and MDA impact to explore the effect of acquired immunity in defined MDA programmes. Compared with scenarios with no immunity, we find that acquired immunity makes the MDA programme less effective with a slower decrease in the prevalence of infection. Therefore, the time to achieve morbidity control and elimination as a public health problem is longer than predicted by models with just age-related exposure and no build-up of immunity. The level of impact depends on the baseline prevalence prior to treatment (the magnitude of the basic reproductive number R0) and the treatment frequency, among other factors. We find that immunity has a larger impact within moderate to high transmission settings such that it is very unlikely to achieve morbidity and transmission control employing current MDA prog
Milne G, Hames T, Scotton C, et al., 2021, Does infection with or vaccination against SARS-CoV-2 lead to lasting immunity?, LANCET RESPIRATORY MEDICINE, Vol: 9, Pages: 1450-1466, ISSN: 2213-2600
Anderson RM, 2021, An urgent need: vaccines for neglected tropical diseases, LANCET INFECTIOUS DISEASES, Vol: 21, Pages: 1621-1623, ISSN: 1473-3099
Anderson RM, Vegvari C, Hollingsworth TD, et al., 2021, The SARS-CoV-2 pandemic: remaining uncertainties in our understanding of the epidemiology and transmission dynamics of the virus, and challenges to be overcome, INTERFACE FOCUS, Vol: 11, ISSN: 2042-8898
Lochen A, Anderson RM, 2021, Dynamic transmission models and economic evaluations of pneumococcal conjugate vaccines: a quality appraisal and limitations (vol 26, pg 60, 2020), CLINICAL MICROBIOLOGY AND INFECTION, Vol: 27, Pages: 1545-1545, ISSN: 1198-743X
Lochen A, Anderson RM, 2021, Dynamic transmission models and economic evaluations of pneumococcal conjugate vaccines: a quality appraisal and limitations, CLINICAL MICROBIOLOGY AND INFECTION, Vol: 27, Pages: 1546-1557, ISSN: 1198-743X
Chong NS, Smith SR, Werkman M, et al., 2021, Modelling the ability of mass drug administration to interrupt soil-transmitted helminth transmission: Community-based deworming in Kenya as a case study, PLOS NEGLECTED TROPICAL DISEASES, Vol: 15, ISSN: 1935-2735
Papaiakovou M, Littlewood TJ, Gasser RB, et al., 2021, How qPCR complements the WHO roadmap (2021-2030) for soil-transmitted helminths, TRENDS IN PARASITOLOGY, Vol: 37, Pages: 698-708, ISSN: 1471-4922
Ayabina D, Kura K, Toor J, et al., 2021, Maintaining low prevalence of Schistosoma mansoni: modelling the effect of less frequent treatment, Clinical Infectious Diseases, Vol: 72, Pages: S140-S145, ISSN: 1058-4838
BACKGROUND: The World Health Organization (WHO) previously set goals of controlling morbidity due to schistosomiasis by 2020 and attaining elimination as a public health problem (EPHP) by 2025 (now adjusted to 2030 in the new neglected tropical diseases roadmap). As these milestones are reached, it is important that programs reassess their treatment strategies to either maintain these goals or progress from morbidity control to EPHP and ultimately to interruption of transmission. In this study, we consider different mass drug administration (MDA) strategies to maintain the goals. METHODS: We use two independently developed individual-based stochastic models of schistosomiasis transmission to assess the optimal treatment strategy of a multi-year program to maintain the morbidity control and the EPHP goals. RESULTS: We find that in moderate prevalence settings, once the morbidity control and EPHP goals are reached, it may be possible to maintain the goals using less frequent MDAs than those that are required to achieve the goals. On the other hand, in some high transmission settings, if control efforts are reduced after achieving the goals, particularly the morbidity control goal, there is a high chance of recrudescence. CONCLUSIONS: To reduce the risk of recrudescence after the goals are achieved, programs have to re-evaluate their strategies and decide to either maintain these goals with reduced efforts where feasible or continue with at least the same efforts required to reach the goals.
Vegvari C, Giardina F, Malizia V, et al., 2021, Impact of Key Assumptions About the Population Biology of Soil-Transmitted Helminths on the Sustainable Control of Morbidity, CLINICAL INFECTIOUS DISEASES, Vol: 72, Pages: S188-S194, ISSN: 1058-4838
Hardwick RJ, Vegvari C, Collyer B, et al., 2021, Spatial scales in human movement between reservoirs of infection, JOURNAL OF THEORETICAL BIOLOGY, Vol: 524, ISSN: 0022-5193
Collyer BS, Anderson RM, 2021, Probability distributions of helminth parasite burdens within the human host population following repeated rounds of mass drug administration and their impact on the transmission breakpoint, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 18, ISSN: 1742-5689
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