Towards Evidence-based Control of Opisthorchis viverrini

Halting the transmission of O. viverrini is crucial to preventing cases cholangiocarcinoma, yet there no consensus on best strategies for large-scale parasite control.Quantitative modelling can provide insights and guide control programmes more rapidly using fewer resources than clinical trials. To give reliable output, models depend making accurate assumptions parameters inferred from relevant datasets.Mathematical dynamics have recently been published a valuable starting point. However, many key epidemiological processes remain poorly understood, including links between exposure, anthelmintic treatment, carcinogenesis.We highlight areas where new studies are required fill knowledge gaps. Recent developments in statistical genomics opportunities make rapid gains. Transmission carcinogenic liver fluke Opisthorchis ongoing across Southeast Asia. Endemic countries within region different stages achieving control. evidence which interventions most effective reducing transmission, resulting cancer, currently lacking. Quantitative be used evaluate measures against assist design In this article we that underpin data necessary their estimation, with aim developing evidence-based at national or regional level. Control initiatives driven by two related aims. Firstly, reduce parasite, leading its elimination (see Glossary). Secondly, halt progression viverrini-induced pathology, thus prevent cholangiocarcinoma [1.Sripa B. et al.Opisthorchiasis Opisthorchis-associated Thailand Laos.Acta Trop. 2011; 120: S158-S168Crossref PubMed Scopus (215) Google Scholar]. endemic regions, definitive hosts become infected through consumption raw insufficiently cooked freshwater fish encysted metacercariae perpetuate life cycle defecating into water sources containing snails Bithynia genus. Programmes therefore number available them, health education promote safe eating habits; case diagnosis treatment; improvements sanitation; food safety controls [2.Khuntikeo N. al.Current perspectives opisthorchiasis detection Asia.Front. Med. 2018; 5: 117Crossref (6) Parasite-induced pathology tackled ultrasound screening detect periductal fibrosis, an early warning sign cholangiocarcinoma; operative surgery improve survival rates [3.Chamadol al.Association fibrosis bile duct dilatation among population high risk cholangiocarcinoma: cross-sectional study Northeast Thailand.BMJ Open. 2019; 9e023217Crossref (4) With such variety tools offer, policy makers, international organisations, affected communities entitled ask: what works? Which interrupting mortality cost-effective, sustainable manner? The traditional method answering question randomised controlled trials, gold standard assessing [4.Grossman J. Mackenzie F.J. randomized trial: standard, merely standard?.Perspec. Biol. 2005; 48: 516-534Crossref (175) Such however, costly, take years, require substantial manpower expertise. It also unethical conduct trials contexts public would withdrawn participants allocated arm trial. An alternative approach use quantitative predictions effectiveness strategies. These myriad forms, parameterised routinely collected field data, considerable insight fraction cost Different types capture macroparasite summarised Box 1.Box 1Modelling ParasitologistsAs parasitologists understand underlying relationships parasites hosts. ecological systems, as infections human populations, usually restricted collecting observational data. leap describing inevitably suffers biases measurement errors, inferring process asking 'what if' questions requires model.Statistical broadly seeks learn estimate biologically meaningful parameters, distribution community, gene flow reinfection rate following treatment. model may mechanistic function explicitly captures data-generating process, less specific generalised linear model. Estimating (or inferring) art itself. common frameworks maximum likelihood Bayesian approaches. methods incorporation prior knowledge, increasingly favoured statisticians they permit parameter estimation complex characterise uncertainty intuitive way [69.McElreath R. Statistical Rethinking: A Course Examples R Stan. CRC Press, 2016Google area has successfully applied spatial parasitic diseases. geostatistical survey taken discrete locations, covariates spatially continuous satellite (such temperature, rainfall, elevation) infer prevalence disease regions [70.Forrer A. al.Spatial of, factors for, infection southern Lao PDR.PLoS Negl. Dis. 2012; 6e1481Crossref (68) Scholar].Mathematical uses equations describe biological system. typically form dynamic compartmental models. Individual agents not considered but rather populations exist states intermediate hosts), transitions determined parameters. synthesis Roy Anderson Robert May mathematical remains text epidemiology [43.Anderson R.M. 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