Publications
257 results found
Catalano S, Symeou A, Marsh KJ, et al., 2019, Mini-FLOTAC as an alternative, non-invasive diagnostic tool for <i>Schistosoma mansoni</i> and other trematode infections in wildlife reservoirs, PARASITES & VECTORS, Vol: 12, ISSN: 1756-3305
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- Citations: 11
Vince L, Gower CM, Binetou-Fall C, et al., 2019, TOWARDS A ONE-HEALTH COST-EFFECTIVENESS EVALUATION OF SCHISTOSOMAISIS CONTROL IN AFRICA, Publisher: OXFORD UNIV PRESS, Pages: S21-S21, ISSN: 0035-9203
Qiu C, Lu D-B, Deng Y, et al., 2019, Population genetics of <i>Oncomelania hupensis</i> snails, intermediate hosts of <i>Schistosoma japonium</i>, from emerging, re-emerging or established habitats within China, ACTA TROPICA, Vol: 197, ISSN: 0001-706X
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- Citations: 5
Chevalier FD, Clech WL, McDew-White M, et al., 2019, Oxamniquine resistance alleles are widespread in Old World<i>Schistosoma mansoni</i>and predate drug deployment
<jats:title>ABSTRACT</jats:title><jats:p>Do mutations required for adaptation occur<jats:italic>de novo</jats:italic>, or are they segregating within populations as standing genetic variation? This question is key to understanding adaptive change in nature, and has important practical consequences for the evolution of drug resistance. We provide evidence that alleles conferring resistance to oxamniquine (OXA), an antischistosomal drug, are widespread in natural parasite populations under minimal drug pressure and predate OXA deployment. OXA has been used since the 1970s to treat<jats:italic>Schistosoma mansoni</jats:italic>infections in the New World where<jats:italic>S. mansoni</jats:italic>established during the slave trade. Recessive loss-of-function mutations within a parasite sulfotransferase (SmSULT-OR) underlie resistance, and several verified resistance mutations, including a deletion (p.E142del), have been identified in the New World. Here we investigate sequence variation in<jats:italic>SmSULT-OR</jats:italic>in<jats:italic>S. mansoni</jats:italic>from the Old World, where OXA has seen minimal usage. We sequenced exomes of 204<jats:italic>S. mansoni</jats:italic>parasites from West Africa, East Africa and the Middle East, and scored variants in<jats:italic>SmSULT-OR</jats:italic>and flanking regions. We identified 39 non-synonymous SNPs, 4 deletions, 1 duplication and 1 premature stop codon in the<jats:italic>SmSULT-OR</jats:italic>coding sequence, including one confirmed resistance deletion (p.E142del). We expressed recombinant proteins and used an<jats:italic>in vitro</jats:italic>OXA activation assay to functionally validate the OXA-resistance phenotype for four predicted OXA-resistance mutations. Three aspects of the data are of particular interest: (i) segregating OXA-resistance alleles are widespread in Old World populations (
Doyle SR, Sankaranarayan G, Allen F, et al., 2019, Evaluation of DNA extraction methods on individual helminth egg and larval stages for whole genome sequencing
<jats:title>Abstract</jats:title><jats:p>Whole genome sequencing is being rapidly applied to the study of helminth genomes, including <jats:italic>de novo</jats:italic> genome assembly, population genetics, and diagnostic applications. Although late-stage juvenile and adult parasites typically produce sufficient DNA for molecular analyses, these parasitic stages are almost always inaccessible in the live host; immature life stages found in the environment for which samples can be collected non-invasively offer a potential alternative, however, these samples are typically yield very low quantities of DNA, can be environmentally resistant, and are susceptible to contamination, often from bacterial or host DNA. Here, we have tested five low-input DNA extraction protocols together with a low-input sequencing library protocol to assess the feasibility of whole genome sequencing of individual immature helminth samples. These approaches do not use whole genome amplification, a common but costly approach to increase the yield of low input samples. We first tested individual parasites from two species spotted onto FTA cards - egg and L1 stages of <jats:italic>Haemonchus contortus</jats:italic> and miracidia of <jats:italic>Schistosoma mansoni</jats:italic> - before further testing on an additional six species - <jats:italic>Ancylostoma caninum, Ascaridia dissimilis, Dirofilaria immitis, Dracunculus medinensis, Strongyloides stercoralis, and Trichuris muris</jats:italic> - with an optimal protocol. Whole genome sequencing followed by analyses to determine the proportion of on- and off-target mapping revealed successful sample preparations for six of the eight species tested with variation between species, and within species but between life stages, described. These results demonstrate the feasibility of whole genome sequencing of individual parasites, and highlight a new avenue towards generating sensitive, spe
Catalano S, Nadler SA, Fall CB, et al., 2019, Plagiorchis sp. in small mammals of Senegal and the potential emergence of a zoonotic trematodiasis, International Journal for Parasitology: Parasites and Wildlife, Vol: 8, Pages: 164-170, ISSN: 2213-2244
Trematodes of the genus Plagiorchis have a wide geographical distribution and can exploit a variety of hosts. The occurrence and zoonotic potential of Plagiorchis spp. have been characterised across several countries in Asia; in contrast, information on Plagiorchis parasites in Africa remains anecdotal. We isolated a previously undescribed Plagiorchis species from the biliary tract and small intestine of 201 out of 427 small mammals collected in the region of Lake Guiers, Senegal, with local prevalence ranging from 38.6% to 77.0%. Conversely, Plagiorchis isolates were not observed in the 244 small mammals sampled in and around the town of Richard Toll, Senegal. Molecular phylogenetics of the internal transcribed spacer region, nuclear ribosomal DNA, and of the cytochrome c oxidase subunit 1 gene, mitochondrial DNA, supported the monophyly and multi-host spectrum of this newly discovered West African Plagiorchis species. Sequencing of individual cercariae shed by Radix natalensis (Gastropoda: Lymnaeidae) suggested that these freshwater snails may act as suitable first intermediate hosts. Phylogenetic analysis yielded a highly resolved topology indicating two different clades, one composed by Plagiorchis spp. infecting rodents, insectivores, and birds, while the other included parasites of bats. Our findings showed the low host specificity and high prevalence of the isolated Plagiorchis sp. in the Lake Guiers region, with Hubert's multimammate mice (Mastomys huberti) appearing to play a primary role in the epidemiology of this parasite. The results raise concern about the zoonotic potential of Plagiorchis sp. in local communities of the Lake Guiers region, and highlight food-borne trematodiases and their link to land-use change as a neglected public health issue in regions of West Africa.
Catalano S, Ba K, Diouf ND, et al., 2019, Rodents of Senegal and their role as intermediate hosts of <i>Hydatigera</i> spp. (Cestoda: Taeniidae), PARASITOLOGY, Vol: 146, Pages: 299-304, ISSN: 0031-1820
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- Citations: 7
Platt RN, McDew-White M, Clech WL, et al., 2019, Ancient hybridization and introgression of an invadolysin gene in schistosome parasites
<jats:p>The parasitic blood fluke<jats:italic>Schistosoma haematobium</jats:italic>causes urogenital schistosomiasis in humans and is a major cause of morbidity and mortality across sub-Saharan Africa.<jats:italic>S. haematobium</jats:italic>hybridizes with livestock schistosomes, including S.<jats:italic>bovis</jats:italic>, however the frequency, direction, age and genomic consequences of hybridization are unknown. We sequenced 96<jats:italic>S. haematobium</jats:italic>exomes from Niger and the Zanzibar archipelago. and found evidence of an ancient, introgression event between Nigerien<jats:italic>S. haematobium</jats:italic>and<jats:italic>S. bovis</jats:italic>occurring 108-613 generations ago. Between 3.3-8.2% of Nigerien<jats:italic>S. haematobium</jats:italic>genomes are derived from<jats:italic>S. bovis</jats:italic>alleles, some of which show signatures of directional selection; the strongest signal spans a single gene in the invadolysin gene family, an M8 metalloprotease associated with parasitic life-history traits.</jats:p>
Suwannahitatorn P, Webster J, Riley S, et al., 2019, Uncooked fish consumption among those at risk of Opisthorchis viverrini infection in central Thailand, PLoS ONE, Vol: 14, Pages: 1-13, ISSN: 1932-6203
In contrast to northern and northeastern Thailand, central Thailand was believed not to be endemic for Opisthorchis viverrini (OV). Fieldwork conducted in a rural area of central Thailand revealed that the prevalence and incidence were relatively high compared with regional average data. We hypothesized that the behavioural-psycho-social background of the study population might play an important role in the high burden of the infection. As a result, a qualitative study was conducted to highlight potential social determinants of the infection dynamics to gain greater understanding of the risk behaviours and their contexts. A qualitative study using focus group discussion and in-depth interviews was conducted in Na-ngam Village, Chachoengsao Province from 2012–14. Framework analysis was used to explore associations between infection and thematic content. Social influence showed a strong impact on infection dynamics of OV infection. Our results revealed that Koi pla (chopped raw fish salad) remains a popular dish in the community, as the dish itself represents northeastern culture. The cultural norm had been transferred from ancestors to their descendants. Some elders complained that discontinuing the consumption of Koi pla went against old traditions with respect to cultural norms and socialization. In contrast, modern education teaches about hygiene including OV infection risks, and accordingly teenagers and young adults were reported to modify their lifestyles including their eating habits. Children are a potential key to pass knowledge to their parents and school-based education programs can serve as a practical hub for knowledge dissemination. However, health education alone might not lead to behavioural change in other age groups. Therefore, more efforts are needed to support the transformation.
Lamberton PHL, Norton AJ, Webster JP, et al., 2019, Propagule behavior and parasite transmission, Encyclopedia of Animal Behavior, Pages: 646-652, ISBN: 9780128132517
Many parasites with complex, indirect, life-cycles involve one or more free-living propagule stages, such as eggs and larvae, which serve in dissemination and transmission between host species. The larvae are often non-feeding and obtain their energy through stored glycogen. These limited energy supplies provide strong constraints and selective pressures to rapidly disperse, and locate, and penetrate a suitable host to complete the life-cycle. Host location can either be achieved by direct attraction to the host, or to a habitat and/or temporal space which is likely to contain the host. Mechanisms for these attractions include kinesis or taxis and are often innate behaviors in response to environmental and/or biological cues. Parasite larval behaviors often involve complex interactions between different stimuli and trade-offs occur between host-seeking and energy-saving traits. These result in a vast array of techniques which aid dispersion and successful transmission. The type of hosts that larvae are required to infect can vary greatly even with a single life-cycle, and parasites have thus evolved complex species- and stage-specific behavioral traits to aid transmission. These are discussed here, with examples focusing on trematode species, where the majority of research has been carried out to date, predominantly due to their medical and veterinary importance.
Mutombo PN, Man NWY, Nejsum P, et al., 2019, Diagnosis and drug resistance of human soil-transmitted helminth infections: A public health perspective, ADVANCES IN PARASITOLOGY, VOL 104, Editors: Rollinson, Stothard, Publisher: ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD, Pages: 247-+
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- Citations: 8
Le Clec'h W, Chevalier FD, McDew-White M, et al., 2018, Whole genome amplification and exome sequencing of archived schistosome miracidia., Parasitology, Vol: 145, Pages: 1739-1747
Adult schistosomes live in the blood vessels and cannot easily be sampled from humans, so archived miracidia larvae hatched from eggs expelled in feces or urine are commonly used for population genetic studies. Large collections of archived miracidia on FTA cards are now available through the Schistosomiasis Collection at the Natural History Museum (SCAN). Here we describe protocols for whole genome amplification of Schistosoma mansoni and Schistosome haematobium miracidia from these cards, as well as real time PCR quantification of amplified schistosome DNA. We used microgram quantities of DNA obtained for exome capture and sequencing of single miracidia, generating dense polymorphism data across the exome. These methods will facilitate the transition from population genetics, using limited numbers of markers to population genomics using genome-wide marker information, maximising the value of collections such as SCAN.
Catalano S, Sene M, Diouf ND, et al., 2018, Rodents as Natural Hosts of Zoonotic <i>Schistosoma</i> Species and Hybrids: An Epidemiological and Evolutionary Perspective From West Africa, JOURNAL OF INFECTIOUS DISEASES, Vol: 218, Pages: 429-433, ISSN: 0022-1899
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- Citations: 57
Pitaksakulrat O, Webster BL, Webster JP, et al., 2018, Phylogenetic relationships within the <i>Opisthorchis viverrini</i> species complex with specific analysis of <i>O-viverrini</i> sensu lato from Sakon Nakhon, Thailand by mitochondrial and nuclear DNA sequencing, INFECTION GENETICS AND EVOLUTION, Vol: 62, Pages: 86-94, ISSN: 1567-1348
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- Citations: 9
Borlase A, Webster JP, Rudge JW, 2018, Opportunities and challenges for modelling epidemiological and evolutionary dynamics in a multihost, multiparasite system: Zoonotic hybrid schistosomiasis in West Africa, EVOLUTIONARY APPLICATIONS, Vol: 11, Pages: 501-515, ISSN: 1752-4571
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- Citations: 11
Lu D-B, Deng Y, Ding H, et al., 2018, Single-sex schistosome infections of definitive hosts: implications for epidemiology and disease control in a changing world, PLoS Pathogens, Vol: 14, ISSN: 1553-7366
Easton A, Lawton S, Gao S, et al., 2018, A REFERENCE <it>ASCARIS LUMBRICOIDES</it> GENOME ALLOWS INSIGHTS INTO POPULATION-BASED GENOMIC CHANGES IN SPACE AND TIME, 67th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTHM), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 211-211, ISSN: 0002-9637
Gower CM, Gehre F, Marques SR, et al., 2017, Phenotypic and genotypic monitoring of Schistosoma mansoni in Tanzanian schoolchildren five years into a preventative chemotherapy national control programme., Parasites & Vectors, Vol: 10, ISSN: 1756-3305
BACKGROUND: Schistosoma mansoni is a parasite of profound medical importance. Current control focusses on mass praziquantel (PZQ) treatment of populations in endemic areas, termed Preventative Chemotherapy (PC). Large-scale PC programmes exert prolonged selection pressures on parasites with the potential for, direct and/or indirect, emergence of drug resistance. Molecular methods can help monitor genetic changes of schistosome populations over time and in response to drug treatment, as well as estimate adult worm burdens through parentage analysis. Furthermore, methods such as in vitro drug sensitivity assays help phenotype in vivo parasite genotypic drug efficacy. METHODS: We conducted combined in vitro PZQ efficacy testing with population genetic analyses of S. mansoni collected from children from two schools in 2010, five years after the introduction of a National Control Programme. Children at one school had received four annual PZQ treatments and the other school had received two mass treatments in total. We compared genetic differentiation, indices of genetic diversity, and estimated adult worm burden from parasites collected in 2010 with samples collected in 2005 (before the control programme began) and in 2006 (six months after the first PZQ treatment). Using 2010 larval samples, we also compared the genetic similarity of those with high and low in vitro sensitivity to PZQ. RESULTS: We demonstrated that there were individual parasites with reduced PZQ susceptibility in the 2010 collections, as evidenced by our in vitro larval behavioural phenotypic assay. There was no evidence, however, that miracidia showing phenotypically reduced susceptibility clustered together genetically. Molecular analysis also demonstrated a significant reduction of adult worm load over time, despite little evidence of reduction in parasite infection intensity, as measured by egg output. Genetic diversity of infections did not reduce over time, despite changes in the genetic composit
Crellen T, Walker M, Lamberton PH, et al., 2017, REDUCED EFFICACY OF PRAZIQUANTEL AGAINST <i>SCHISTOSOMA MANSONI</i> IS ASSOCIATED WITH MULTIPLE-ROUNDS OF MASS DRUG ADMINISTRATION: EPIDEMIOLOGICAL AND GENOMIC DATA FROM UGANDA, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 195-195, ISSN: 0002-9637
Deol AK, French MD, Walker M, et al., 2017, COMMUNITY-WIDE PATTERNS OF INFECTION AFTER MORE THAN TEN YEARS OF PREVENTIVE CHEMOTHERAPY FOR SCHISTOSOMIASIS AND SOIL-TRANSMITTED HELMINTH INFECTION IN UGANDA: ARE WE READY TO MOVE BEYOND MORBIDITY CONTROL?, 65th Annual Meeting of the American-Society-of-Tropical-Medicine-and-Hygiene (ASTMH), Publisher: AMER SOC TROP MED & HYGIENE, Pages: 558-558, ISSN: 0002-9637
Gower CM, Vince L, Webster JP, 2017, Should we be treating animal schistosomiasis in Africa? The need for a One Health economic evaluation of schistosomiasis control in people and their livestock., Transactions of The Royal Society of Tropical Medicine and Hygiene, Vol: 111, Pages: 244-247, ISSN: 0035-9203
A One Health economic perspective allows informed decisions to be made regarding control priorities and/or implementation strategies for infectious diseases. Schistosomiasis is a major and highly resilient disease of both humans and livestock. The zoonotic component of transmission in sub-Saharan Africa appears to be more significant than previously assumed, and may thereby affect the recently revised WHO vision to eliminate schistosomiasis as a public health problem by 2025. Moreover, animal schistosomiasis is likely to be a significant cost to affected communities due to its direct and indirect impact on livelihoods. We argue here for a comprehensive evaluation of the economic burden of livestock and zoonotic schistosomiasis in sub-Saharan Africa in order to determine if extending treatment to include animal hosts in a One Health approach is economically, as well as epidemiologically, desirable.
Viana M, Faust CL, Haydon DT, et al., 2017, The effects of subcurative praziquantel treatment on life-history traits and trade-offs in drug-resistant Schistosoma mansoni, Evolutionary Applications, Vol: 11, Pages: 488-500, ISSN: 1752-4571
Natural selection acts on all organisms, including parasites, to maximize reproductive fitness. Drug resistance traits are often associated with life-history costs in the absence of treatment. Schistosomiasis control programmes rely on mass drug administration to reduce human morbidity and mortality. Although hotspots of reduced drug efficacy have been reported, resistance is not widespread. Using Bayesian state-space models (SSMs) fitted to data from an in vivo laboratory system, we tested the hypothesis that the spread of resistant Schistosoma mansoni may be limited by life-history costs not present in susceptible counterparts. S. mansoni parasites from a praziquantel-susceptible (S), a praziquantel-resistant (R) or a mixed line of originally resistant and susceptible parasites (RS) were exposed to a range of praziquantel doses. Parasite numbers at each life stage were quantified in their molluscan intermediate and murine definitive hosts across four generations, and SSMs were used to estimate key life-history parameters for each experimental group over time. Model outputs illustrated that parasite adult survival and fecundity in the murine host decreased across all lines, including R, with increasing drug pressure. Trade-offs between adult survival and fecundity were observed in all untreated lines, and these remained strong in S with praziquantel pressure. In contrast, trade-offs between adult survival and fecundity were lost under praziquantel pressure in R. As expected, parasite life-history traits within the molluscan host were complex, but trade-offs were demonstrated between parasite establishment and cercarial output. The observed trade-offs between generations within hosts, which were modified by praziquantel treatment in the R line, could limit the spread of R parasites under praziquantel pressure. Whilst such complex life-history costs may be difficult to detect using standard empirical methods, we demonstrate that SSMs provide robust estimates of life-
Lamberton PHL, Faust CL, Webster JP, 2017, Praziquantel decreases fecundity in Schistosoma mansoni adult worms that survive treatment: evidence from a laboratory life-history trade-offs selection study, Infectious Diseases of Poverty, Vol: 6, ISSN: 2049-9957
BackgroundMass drug administration of praziquantel is the World Health Organization’s endorsed control strategy for schistosomiasis. A decade of annual treatments across sub-Saharan Africa has resulted in significant reductions of infection prevalence and intensity levels, although ‘hotspots’ remain. Repeated drug treatments place strong selective pressures on parasites, which may affect life-history traits that impact transmission dynamics. Understanding drug treatment responses and the evolution of such traits can help inform on how to minimise the risk of drug resistance developing, maximise sustainable control programme success, and improve diagnostic protocols.MethodsWe performed a four-generation Schistosoma mansoni praziquantel selection experiment in mice and snails. We used three S. mansoni lines: a praziquantel-resistant isolate (R), a praziquantel-susceptible isolate (S), and a co-infected line (RS), under three treatment regimens: untreated, 25 mg/kg praziquantel, or 50 mg/kg praziquantel. Life-history traits, including parasite adult-worm establishment, survival, reproduction (fecundity), and associated morbidity, were recorded in mice across all four generations. Predictor variables were tested in a series of generalized linear mixed effects models to determine which factors had a significant influence on parasite life-history traits in definitive hosts under different selection regimes.ResultsPraziquantel pressure significantly reduced adult-worm burdens across all generations and isolates, including within R-lines. However, previous drug treatment resulted in an increase in adult-worm establishment with increasing generation from P1 to F3. The highest worm numbers were in the co-infected RS line. Praziquantel treatment decreased adult-worm burden, but had a larger negative impact on the mean daily number of miracidia, a proxy for fecundity, across all three parasite isolates.ConclusionsOur predicted cost of resistance was not suppor
Easton AV, Oliveira RG, Walker M, et al., 2017, Sources of variability in the measurement of Ascaris lumbricoides infection intensity by Kato-Katz and qPCR, Parasites & Vectors, Vol: 10, ISSN: 1756-3305
BackgroundUnderstanding and quantifying the sources and implications of error in the measurement of helminth egg intensity using Kato-Katz (KK) and the newly emerging “gold standard” quantitative polymerase chain reaction (qPCR) technique is necessary for the appropriate design of epidemiological studies, including impact assessments for deworming programs.MethodsRepeated measurements of Ascaris lumbricoides infection intensity were made from samples collected in western Kenya using the qPCR and KK techniques. These data were combined with data on post-treatment worm expulsions. Random effects regression models were used to quantify the variability associated with different technical and biological factors for qPCR and KK diagnosis. The relative precision of these methods was compared, as was the precision of multiple qPCR replicates.ResultsFor both KK and qPCR, intensity measurements were largely determined by the identity of the stool donor. Stool donor explained 92.4% of variability in qPCR measurements and 54.5% of observed measurement variance for KK. An additional 39.1% of variance in KK measurements was attributable to having expelled adult A. lumbricoides worms following anthelmintic treatment. For qPCR, the remaining 7.6% of variability was explained by the efficiency of the DNA extraction (2.4%), plate-to-plate variability (0.2%) and other residual factors (5%). Differences in replicate measurements by qPCR were comparatively small. In addition to KK variability based on stool donor infection levels, the slide reader was highly statistically significant, although it only explained 1.4% of the total variation. In a comparison of qPCR and KK variance to mean ratios under ideal conditions, the coefficient of variation was on average 3.6 times larger for KK highlighting increased precision of qPCR.ConclusionsPerson-to-person differences explain the majority of variability in egg intensity measurements by qPCR and KK, with very little additional var
Antonovics J, Wilson AJ, Forbes MR, et al., 2017, The evolution of transmission mode, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 372, ISSN: 0962-8436
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- Citations: 61
Pitaksakulrat O, Kiatsopit N, Laoprom N, et al., 2017, Preliminary genetic evidence of two different populations of <i>Opisthorchis viverrini</i> in Lao PDR, PARASITOLOGY RESEARCH, Vol: 116, Pages: 1247-1256, ISSN: 0932-0113
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- Citations: 9
Webster JP, Borlase A, Rudge JW, 2017, Who acquires infection from whom and how? Disentangling multi-host and multi-mode transmission dynamics in the 'elimination' era., Philosophical Transactions B: Biological Sciences, Vol: 372, ISSN: 0962-8436
Multi-host infectious agents challenge our abilities to understand, predict and manage disease dynamics. Within this, many infectious agents are also able to use, simultaneously or sequentially, multiple modes of transmission. Furthermore, the relative importance of different host species and modes can itself be dynamic, with potential for switches and shifts in host range and/or transmission mode in response to changing selective pressures, such as those imposed by disease control interventions. The epidemiology of such multi-host, multi-mode infectious agents thereby can involve a multi-faceted community of definitive and intermediate/secondary hosts or vectors, often together with infectious stages in the environment, all of which may represent potential targets, as well as specific challenges, particularly where disease elimination is proposed. Here, we explore, focusing on examples from both human and animal pathogen systems, why and how we should aim to disentangle and quantify the relative importance of multi-host multi-mode infectious agent transmission dynamics under contrasting conditions, and ultimately, how this can be used to help achieve efficient and effective disease control.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
Leger E, Webster JP, 2017, Hybridizations within the Genus <i>Schistosoma</i>: implications for evolution, epidemiology and control, PARASITOLOGY, Vol: 144, Pages: 65-80, ISSN: 0031-1820
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- Citations: 89
Leger E, Garba A, Hamidou AA, et al., 2016, Introgressed Animal Schistosomes <i>Schistosoma</i> <i>curassoni</i> and <i>S.</i> <i>bovis</i> Naturally Infecting Humans, EMERGING INFECTIOUS DISEASES, Vol: 22, Pages: 2212-2214, ISSN: 1080-6040
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- Citations: 31
Deol AK, Webster JP, walker M, et 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, ISSN: 1756-3305
Background: Understanding whether schistosomiasis control programmes are on course to control morbidityand potentially switch towards elimination interventions would benefit from user-friendly quantitative tools thatfacilitate analysis of progress and highlight areas not responding to treatment. This study aimed to develop andevaluate such a tool using large datasets collected during Schistosomiasis Control Initiative-supported controlprogrammes.Methods: A discrete-time Markov model was developed using transition probability matrices parameterized withcontrol 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 Aused data at baseline and year 1 of the control programme; B used year 1 and year 2; C used baseline and year 1from selected districts, and D used baseline and year 1 Mali data. Model predictions were tested against 3 subsetsof the Uganda dataset: dataset 1, the full 4-year longitudinal cohort; dataset 2, from districts not used toparameterize 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 andwhen stratified by infection intensity). Matrices A-D successfully predicted prevalence in each follow-up year for lowand high intensity categories in dataset 1 followed by dataset 2. Matrices A, B and D yielded similar and closematches to dataset 1 with marginal discrepancies when comparing model outputs against datasets 2 and 3. MatrixC produced more variable results, correctly estimating fewer data points.Conclusion: Model outputs closely matched observed values and were a useful predictor of the infection dynamicsof S. mansoni when using longitudinal and cross-sectional data from Uganda. This also held when the model wastested with data from Mali. This was most
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