Imperial College London

Joanne P. Webster

Faculty of MedicineSchool of Public Health

Visiting Professor
 
 
 
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Contact

 

joanne.webster Website

 
 
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Location

 

Medical SchoolSt Mary's Campus

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Summary

 

Publications

Publication Type
Year
to

235 results found

Li Y, Bletsa M, Zisi Z, Boonen I, Gryseels S, Kafetzopoulou L, Webster JP, Catalano S, Pybus OG, Van de Perre F, Li H, Li Y, Li Y, Abramov A, Lymberakis P, Lemey P, Lequime Set al., 2022, Endogenous Viral Elements in Shrew Genomes Provide Insights into Pestivirus Ancient History., Mol Biol Evol, Vol: 39

As viral genomic imprints in host genomes, endogenous viral elements (EVEs) shed light on the deep evolutionary history of viruses, ancestral host ranges, and ancient viral-host interactions. In addition, they may provide crucial information for calibrating viral evolutionary timescales. In this study, we conducted a comprehensive in silico screening of a large data set of available mammalian genomes for EVEs deriving from members of the viral family Flaviviridae, an important group of viruses including well-known human pathogens, such as Zika, dengue, or hepatitis C viruses. We identified two novel pestivirus-like EVEs in the reference genome of the Indochinese shrew (Crocidura indochinensis). Homologs of these novel EVEs were subsequently detected in vivo by molecular detection and sequencing in 27 shrew species, including 26 species representing a wide distribution within the Crocidurinae subfamily and one in the Soricinae subfamily on different continents. Based on this wide distribution, we estimate that the integration event occurred before the last common ancestor of the subfamily, about 10.8 million years ago, attesting to an ancient origin of pestiviruses and Flaviviridae in general. Moreover, we provide the first description of Flaviviridae-derived EVEs in mammals even though the family encompasses numerous mammal-infecting members. This also suggests that shrews were past and perhaps also current natural reservoirs of pestiviruses. Taken together, our results expand the current known Pestivirus host range and provide novel insight into the ancient evolutionary history of pestiviruses and the Flaviviridae family in general.

Journal article

Pennance T, Neves MI, Webster BL, Gower CM, Knopp S, Khamis IS, Ame SM, Ali SM, Rabone M, Emery A, Allan F, Muhsin MA, Suleiman KR, Kabole F, Walker M, Rollinson D, Webster JPet al., 2022, Potential drivers for schistosomiasis persistence: Population genetic analyses from a cluster-randomized urogenital schistosomiasis elimination trial across the Zanzibar islands., PLoS Negl Trop Dis, Vol: 16

The World Health Organization's revised NTD Roadmap and the newly launched Guidelines target elimination of schistosomiasis as a public health problem in all endemic areas by 2030. Key to meeting this goal is elucidating how selective pressures imposed by interventions shape parasite populations. Our aim was to identify any differential impact of a unique cluster-randomized tri-armed elimination intervention (biannual mass drug administration (MDA) applied alone or in association with either mollusciciding (snail control) or behavioural change interventions) across two Zanzibarian islands (Pemba and Unguja) on the population genetic composition of Schistosoma haematobium over space and time. Fifteen microsatellite loci were used to analyse individual miracidia collected from infected individuals across islands and intervention arms at the start (2012 baseline: 1,522 miracidia from 176 children; 303 from 43 adults; age-range 6-75, mean 12.7 years) and at year 5 (2016: 1,486 miracidia from 146 children; 214 from 25 adults; age-range 9-46, mean 12.4 years). Measures of genetic diversity included allelic richness (Ar), Expected (He) and Observed heterozygosity (Ho), inbreeding coefficient (FST), parentage analysis, estimated worm burden, worm fecundity, and genetic sub-structuring. There was little evidence of differential selective pressures on population genetic diversity, inbreeding or estimated worm burdens by treatment arm, with only the MDA+snail control arm within Unguja showing trends towards reduced diversity and altered inbreeding over time. The greatest differences overall, both in terms of parasite fecundity and genetic sub-structuring, were observed between the islands, consistent with Pemba's persistently higher mean infection intensities compared to neighbouring Unguja, and within islands in terms of infection hotspots (across three definitions). These findings highlight the important contribution of population genetic analyses to elucidate extensive gene

Journal article

Berger DJ, Léger E, Sankaranarayanan G, Sène M, Diouf ND, Rabone M, Emery A, Allan F, Cotton JA, Berriman M, Webster JPet al., 2022, Genomic evidence of contemporary hybridization between Schistosoma species., PLoS Pathog, Vol: 18

Hybridization between different species of parasites is increasingly being recognised as a major public and veterinary health concern at the interface of infectious diseases biology, evolution, epidemiology and ultimately control. Recent research has revealed that viable hybrids and introgressed lineages between Schistosoma spp. are prevalent across Africa and beyond, including those with zoonotic potential. However, it remains unclear whether these hybrid lineages represent recent hybridization events, suggesting hybridization is ongoing, and/or whether they represent introgressed lineages derived from ancient hybridization events. In human schistosomiasis, investigation is hampered by the inaccessibility of adult-stage worms due to their intravascular location, an issue which can be circumvented by post-mortem of livestock at abattoirs for Schistosoma spp. of known zoonotic potential. To characterise the composition of naturally-occurring schistosome hybrids, we performed whole-genome sequencing of 21 natural livestock infective schistosome isolates. To facilitate this, we also assembled a de novo chromosomal-scale draft assembly of Schistosoma curassoni. Genomic analyses identified isolates of S. bovis, S. curassoni and hybrids between the two species, all of which were early generation hybrids with multiple generations found within the same host. These results show that hybridization is an ongoing process within natural populations with the potential to further challenge elimination efforts against schistosomiasis.

Journal article

Lo NC, Bezerra FSM, Colley DG, Fleming FM, Homeida M, Kabatereine N, Kabole FM, King CH, Mafe MA, Midzi N, Mutapi F, Mwanga JR, Ramzy RMR, Satrija F, Stothard JR, Traoré MS, Webster JP, Utzinger J, Zhou X-N, Danso-Appiah A, Eusebi P, Loker ES, Obonyo CO, Quansah R, Liang S, Vaillant M, Murad MH, Hagan P, Garba Aet al., 2022, Review of 2022 WHO guidelines on the control and elimination of schistosomiasis., Lancet Infectious Diseases, ISSN: 1473-3099

Schistosomiasis is a helminthiasis infecting approximately 250 million people worldwide. In 2001, the World Health Assembly (WHA) 54.19 resolution defined a new global strategy for control of schistosomiasis through preventive chemotherapy programmes. This resolution culminated in the 2006 WHO guidelines that recommended empirical treatment by mass drug administration with praziquantel, predominately to school-aged children in endemic settings at regular intervals. Since then, school-based and community-based preventive chemotherapy programmes have been scaled-up, reducing schistosomiasis-associated morbidity. Over the past 15 years, new scientific evidence-combined with a more ambitious goal of eliminating schistosomiasis and an increase in the global donated supply of praziquantel-has highlighted the need to update public health guidance worldwide. In February, 2022, WHO published new guidelines with six recommendations to update the global public health strategy against schistosomiasis, including expansion of preventive chemotherapy eligibility from the predominant group of school-aged children to all age groups (2 years and older), lowering the prevalence threshold for annual preventive chemotherapy, and increasing the frequency of treatment. This Review, written by the 2018-2022 Schistosomiasis Guidelines Development Group and its international partners, presents a summary of the new WHO guideline recommendations for schistosomiasis along with their historical context, supporting evidence, implications for public health implementation, and future research needs.

Journal article

Liang S, Ponpetch K, Zhou Y-B, Guo J, Erko B, Stothard JR, Murad MH, Zhou X-N, Satrija F, Webster JP, Remais JV, Utzinger J, Garba Aet al., 2022, Diagnosis of Schistosoma infection in non-human animal hosts: A systematic review and meta-analysis., PLoS Negl Trop Dis, Vol: 16

BACKGROUND: Reliable and field-applicable diagnosis of schistosome infections in non-human animals is important for surveillance, control, and verification of interruption of human schistosomiasis transmission. This study aimed to summarize uses of available diagnostic techniques through a systematic review and meta-analysis. METHODOLOGY AND PRINCIPAL FINDINGS: We systematically searched the literature and reports comparing two or more diagnostic tests in non-human animals for schistosome infection. Out of 4,909 articles and reports screened, 19 met our inclusion criteria, four of which were considered in the meta-analysis. A total of 14 techniques (parasitologic, immunologic, and molecular) and nine types of non-human animals were involved in the studies. Notably, four studies compared parasitologic tests (miracidium hatching test (MHT), Kato-Katz (KK), the Danish Bilharziasis Laboratory technique (DBL), and formalin-ethyl acetate sedimentation-digestion (FEA-SD)) with quantitative polymerase chain reaction (qPCR), and sensitivity estimates (using qPCR as the reference) were extracted and included in the meta-analyses, showing significant heterogeneity across studies and animal hosts. The pooled estimate of sensitivity was 0.21 (95% confidence interval (CI): 0.03-0.48) with FEA-SD showing highest sensitivity (0.89, 95% CI: 0.65-1.00). CONCLUSIONS/SIGNIFICANCE: Our findings suggest that the parasitologic technique FEA-SD and the molecular technique qPCR are the most promising techniques for schistosome diagnosis in non-human animal hosts. Future studies are needed for validation and standardization of the techniques for real-world field applications.

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Marsh KJ, Raulo AM, Brouard M, Troitsky T, English HM, Allen B, Raval R, Venkatesan S, Pedersen AB, Webster JP, Knowles SCLet al., 2022, Synchronous Seasonality in the Gut Microbiota of Wild Mouse Populations, FRONTIERS IN MICROBIOLOGY, Vol: 13

Journal article

Raj E, Calvo-Urbano B, Heffernan C, Halder J, Webster JPet al., 2022, Systematic review to evaluate a potential association between helminth infection and physical stunting in children, PARASITES & VECTORS, Vol: 15, ISSN: 1756-3305

Journal article

Adeyemo P, Leger E, Hollenberg E, Diouf N, Sene M, Webster JP, Hasler Bet al., 2022, Estimating the financial impact of livestock schistosomiasis on traditional subsistence and transhumance farmers keeping cattle, sheep and goats in northern Senegal, PARASITES & VECTORS, Vol: 15, ISSN: 1756-3305

Journal article

Platt RN, Le Clec'h W, Chevalier FD, McDew-White M, LoVerde PT, de Assis RR, Oliveira G, Kinung'hi S, Djirmay AG, Steinauer ML, Gouvras A, Rabone M, Allan F, Webster BL, Webster JP, Emery AM, Rollinson D, Anderson TJCet al., 2022, Genomic analysis of a parasite invasion: Colonization of the Americas by the blood fluke Schistosoma mansoni, MOLECULAR ECOLOGY, Vol: 31, Pages: 2242-2263, ISSN: 0962-1083

Journal article

Walker M, Freitas LT, Halder JB, Brack M, Keiser J, King CH, Levecke B, Ai-Lian Lim Y, Pieri O, Sow D, Stothard JR, Webster JP, Zhou X-N, Terry RF, Guérin PJ, Basáñez M-Get al., 2022, Improving anthelmintic treatment for schistosomiasis and soil-transmitted helminthiases through sharing and reuse of individual participant data., Wellcome Open Res, Vol: 7, ISSN: 2398-502X

The Infectious Diseases Data Observatory (IDDO, https://www.iddo.org) has launched a clinical data platform for the collation, curation, standardisation and reuse of individual participant data (IPD) on treatments for two of the most globally important neglected tropical diseases (NTDs), schistosomiasis (SCH) and soil-transmitted helminthiases (STHs). This initiative aims to harness the power of data-sharing by facilitating collaborative joint analyses of pooled datasets to generate robust evidence on the efficacy and safety of anthelminthic treatment regimens. A crucial component of this endeavour has been the development of a Research Agenda to promote engagement with the SCH and STH research and disease control communities by highlighting key questions that could be tackled using data shared through the IDDO platform. Here, we give a contextual overview of the priority research themes articulated in the Research Agenda-a 'living' document hosted on the IDDO website-and describe the three-stage consultation process behind its development. We also discuss the sustainability and future directions of the platform, emphasising throughout the power and promise of ethical and equitable sharing and reuse of clinical data to support the elimination of NTDs.

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Le Clec'h W, Chevalier FD, Mattos ACA, Strickland A, Diaz R, McDew-White M, Rohr CM, Kinung'hi S, Allan F, Webster BL, Webster JP, Emery AM, Rollinson D, Djirmay AG, Al Mashikhi KM, Al Yafae S, Idris MA, Mone H, Mouahid G, LoVerde P, Marchant JS, Anderson TJCet al., 2021, Genetic analysis of praziquantel response in schistosome parasites implicates a transient receptor potential channel, SCIENCE TRANSLATIONAL MEDICINE, Vol: 13, ISSN: 1946-6234

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Díaz AV, Walker M, Webster JP, 2021, Surveillance and control of SARS-CoV-2 in mustelids: An evolutionary perspective., Evolutionary Applications: evolutionary approaches to environmental, biomedical and socio-economic issues, Vol: 14, Pages: 2715-2725, ISSN: 1752-4563

The relevance of mustelids in SARS-CoV-2 transmission has become increasingly evident. Alongside experimental demonstration of airborne transmission among ferrets, the major animal model for human respiratory diseases, transmission of SARS-CoV-2 within- and/or between-commercial mink farms has occurred and continues to occur. The number of mink reared for the luxury fur trade is approximately 60.5 million, across 36 mustelid-farming countries. By July 2021, SARS-CoV-2 outbreaks have been reported in 12 of these countries, at 412 European and 20 North American mink farms. Reverse zoonotic transmission events (from humans to mink) have introduced the virus to farms with subsequent extensive mink-to-mink transmission as well as further zoonotic (mink-to-human) transmission events generating cases among both farm workers and the broader community. Overcrowded housing conditions inherent within intensive mink farms, often combined with poor sanitation and welfare, both guarantee spread of SARS-CoV-2 and facilitate opportunities for viral variants, thereby effectively representing biotic hubs for viral transmission and evolution of virulence. Adequate preventative, surveillance and control measures within the mink industry are imperative both for the control of the current global pandemic and to mitigate against future outbreaks.

Journal article

Borlase A, Rudge JW, Leger E, Diouf ND, Fall CB, Diop SD, Catalano S, Sene M, Webster JPet al., 2021, Spillover, hybridization, and persistence in schistosome transmission dynamics at the human-animal interface, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 118, ISSN: 0027-8424

Journal article

Behnke JM, Stewart A, Smales L, Cooper G, Lowe A, Kinsella JM, Bajer A, Dwuznik-Szarek D, Herman J, Fenn J, Catalano S, Diagne CA, Webster JPet al., 2021, Parasitic nematodes of the genus Syphacia Seurat, 1916 infecting Cricetidae in the British Isles: the enigmatic status of Syphacia nigeriana, PARASITOLOGY, Vol: 149, Pages: 76-94, ISSN: 0031-1820

Journal article

Lu D-B, Yu Q-F, Zhang J-Y, Sun M-T, Gu M-M, Webster JP, Liang Y-Set al., 2021, Extended survival and reproductive potential of single-sex male and female Schistosoma japonicum within definitive hosts, INTERNATIONAL JOURNAL FOR PARASITOLOGY, Vol: 51, Pages: 887-891, ISSN: 0020-7519

Journal article

Fall CB, Lambert S, Leger E, Yasenev L, Garba AD, Diop SD, Borlase A, Catalano S, Faye B, Walker M, Sene M, Webster JPet al., 2021, Hybridized zoonotic schistosoma infections result in hybridized morbidity profiles: a clinical morbidity study amongst co-infected human populations of Senegal, Microorganisms, Vol: 9, Pages: 1-18, ISSN: 2076-2607

Hybridization of infectious agents is a major emerging public and veterinary health concern at the interface of evolution, epidemiology, and control. Whilst evidence of the extent of hybridization amongst parasites is increasing, their impact on morbidity remains largely unknown. This may be predicted to be particularly pertinent where parasites of animals with contrasting pathogenicity viably hybridize with human parasites. Recent research has revealed that viable zoonotic hybrids between human urogenital Schistosoma haematobium with intestinal Schistosoma species of livestock, notably Schistosoma bovis, can be highly prevalent across Africa and beyond. Examining human populations in Senegal, we found increased hepatic but decreased urogenital morbidity, and reduced improvement following treatment with praziquantel, in those infected with zoonotic hybrids compared to non-hybrids. Our results have implications for effective monitoring and evaluation of control programmes, and demonstrate for the first time the potential impact of parasite hybridizations on host morbidity.

Journal article

Berger DJ, Crellen T, Lamberton PHL, Allan F, Tracey A, Noonan JD, Kabatereine NB, Tukahebwa EM, Adriko M, Holroyd N, Webster JP, Berriman M, Cotton JAet al., 2021, Whole-genome sequencing of Schistosoma mansoni reveals extensive diversity with limited selection despite mass drug administration, NATURE COMMUNICATIONS, Vol: 12, ISSN: 2041-1723

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Yu Q-F, Zhang J-Y, Sun M-T, Gu M-M, Zou H-Y, Webster JP, Lu D-Bet al., 2021, In vivo praziquantel efficacy of Schistosoma japonicum over time: A systematic review and meta-analysis, ACTA TROPICA, Vol: 222, ISSN: 0001-706X

Journal article

Neves MI, Gower CM, Webster JP, Walker Met al., 2021, Revisiting density-dependent fecundity in schistosomes using sibship reconstruction., PLoS Neglected Tropical Diseases, Vol: 15, Pages: 1-16, ISSN: 1935-2727

The stability of parasite populations is regulated by density-dependent processes occurring at different stages of their life cycle. In dioecious helminth infections, density-dependent fecundity is one such regulatory process that describes the reduction in egg production by female worms in high worm burden within-host environments. In human schistosomiasis, the operation of density-dependent fecundity is equivocal and investigation is hampered by the inaccessibility of adult worms that are located intravascularly. Current understanding is almost exclusively limited to data collected from two human autopsy studies conducted over 40 years ago, with subsequent analyses having reached conflicting conclusions. Whether egg production is regulated in a density-dependent manner is key to predicting the effectiveness of interventions targeting the elimination of schistosomiasis and to the interpretation of parasitological data collected during monitoring and evaluation activities. Here, we revisit density-dependent fecundity in the two most globally important human Schistosoma spp. using a statistical modelling approach that combines molecular inference on the number of parents/adult worms in individual human hosts with parasitological egg count data from mainland Tanzania and Zanzibar. We find a non-proportional relationship between S. haematobium egg counts and inferred numbers of female worms, providing the first clear evidence of density-dependent fecundity in this schistosome species. We do not find robust evidence for density-dependent fecundity in S. mansoni because of high sensitivity to some modelling assumptions and the lower statistical power of the available data. We discuss the strengths and limitations of our model-based analytical approach and its potential for improving our understanding of density dependence in schistosomiasis and other human helminthiases earmarked for elimination.

Journal article

Mawa PA, Kincaid-Smith J, Tukahebwa EM, Webster JP, Wilson Set al., 2021, Schistosomiasis morbidity hotspots: roles of the human host, the parasite and their interface in the Development of severe morbidity, Frontiers in Immunology, Vol: 12, ISSN: 1664-3224

Schistosomiasis is the second most important human parasitic disease in terms of socioeconomic impact, causing great morbidity and mortality, predominantly across the African continent. For intestinal schistosomiasis, severe morbidity manifests as periportal fibrosis (PPF) in which large tracts of macro-fibrosis of the liver, visible by ultrasound, can occlude the main portal vein leading to portal hypertension (PHT), sequelae such as ascites and collateral vasculature, and ultimately fatalities. For urogenital schistosomiasis, severe morbidity manifests as pathology throughout the urinary system and genitals, and is a definitive cause of squamous cell bladder carcinoma. Preventative chemotherapy (PC) programmes, delivered through mass drug administration (MDA) of praziquantel (PZQ), have been at the forefront of schistosomiasis control programmes in sub-Saharan Africa since their commencement in Uganda in 2003. However, despite many successes, 'biological hotspots' (as distinct from 'operational hotspots') of both persistent high transmission and morbidity remain. In some areas, this failure to gain control of schistosomiasis has devastating consequences, with not only persistently high infection intensities, but both "subtle" and severe morbidity remaining prevalent. These hotspots highlight the requirement to revisit research into severe morbidity and its mechanisms, a topic that has been out of favor during times of PC implementation. Indeed, the focality and spatially-structured epidemiology of schistosomiasis, its transmission persistence and the morbidity induced, has long suggested that gene-environmental-interactions playing out at the host-parasite interface are crucial. Here we review evidence of potential unique parasite factors, host factors, and their gene-environmental interactions in terms of explaining differential morbidity profiles in the human host. We then take the situation of schistosomiasis mansoni within the Albertin

Journal article

Jones BP, Norman BF, Borrett HE, Attwood SW, Mondal MMH, Walker AJ, Webster JP, Rajapakse RPVJ, Lawton SPet al., 2021, Author Correction: Divergence across mitochondrial genomes of sympatric members of the Schistosoma indicum group and clues into the evolution of Schistosoma spindale., Sci Rep, Vol: 11

Journal article

Levecke B, Vlaminck J, Andriamaro L, Ame S, Belizario V, Degarege A, Engels D, Erko B, Garba AD, Kaatano GM, Mekonnen Z, Montresor A, Olliaro P, Pieri OS, Sacko M, Sam-Wobo SO, Tchuente LAT, Webster JP, Vercruysse Jet al., 2020, Evaluation of the therapeutic efficacy of praziquantel against schistosomes in seven countries with ongoing large-scale deworming programs, INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE, Vol: 14, Pages: 183-187, ISSN: 2211-3207

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Milne G, Webster JP, Walker M, 2020, Toxoplasma gondii: An Underestimated Threat?, TRENDS IN PARASITOLOGY, Vol: 36, Pages: 959-969, ISSN: 1471-4922

Journal article

Namsanor J, Pitaksakulrat O, Kopolrat K, Kiatsopit N, Webster BL, Gower CM, Webster JP, Laha T, Saijuntha W, Laoprom N, Andrews RH, Petney TN, Blair D, Sithithaworn Pet al., 2020, Impact of geography and time on genetic clusters of Opisthorchis viverrini identified by microsatellite and mitochondrial DNA analysis, INTERNATIONAL JOURNAL FOR PARASITOLOGY, Vol: 50, Pages: 1133-1144, ISSN: 0020-7519

Journal article

Milne G, Webster JP, Walker M, 2020, Towards improving interventions against toxoplasmosis by identifying routes of transmission using sporozoite-specific serological tools., Clinical Infectious Diseases, Vol: 71, Pages: e686-e693, ISSN: 1058-4838

BACKGROUND: Horizontal transmission of Toxoplasma gondii occurs primarily via ingestion of environmental oocysts or consumption of undercooked/raw meat containing cyst-stage bradyzoites. The relative importance of these two transmission routes remains unclear. Oocyst infection can be distinguished from bradyzoite infection by identification of IgG antibodies against T. gondii-embryogenesis-related protein (TgERP). These antibodies are, however, thought to persist for only 6-8 months in human sera, limiting the use of TgERP serology to only those patients recently exposed to T. gondii. Yet recent serological survey data indicate a more sustained persistence of anti-TgERP antibodies. Elucidating the duration of anti-TgERP IgG will help to determine whether TgERP serology has epidemiological utility for quantifying the relative importance of different routes of T. gondii transmission. METHODS: We developed a sero-catalytic mathematical model to capture the change in seroprevalence of non-stage-specific IgG and anti-TgERP IgG antibodies with human age. The model was fitted to published datasets collected in an endemic region of Brazil to estimate the duration of anti-TgERP IgG antibodies, accounting for variable age-force of infection profiles and uncertainty in the diagnostic performance of TgERP serology. RESULTS: We found that anti-TgERP IgG persists for substantially longer than previously recognised, with estimates ranging from 8.3 to 41.1 years. The Brazilian datasets were consistent with oocysts being the predominant transmission route in these settings. CONCLUSIONS: The longer than previously recognised duration of anti-TgERP antibodies indicates that anti-TgERP serology could be a useful tool for delineating T. gondii transmission routes in human populations. TgERP serology may therefore be an important epidemiological tool for informing the design of tailored, setting-specific public health information campaigns and interventions.

Journal article

Easton A, Gao S, Lawton SP, Bennuru S, Khan A, Dahlstrom E, Oliveira RG, Kepha S, Porcella SF, Webster J, Anderson R, Grigg ME, Davis RE, Wang J, Nutman TBet al., 2020, Molecular evidence of hybridization between pig and human Ascaris indicates an interbred species complex infecting humans, eLife, Vol: 9, ISSN: 2050-084X

Human ascariasis is a major neglected tropical disease caused by the nematode Ascaris lumbricoides. We report a 296 megabase (Mb) reference-quality genome comprised of 17,902 protein-coding genes derived from a single, representative Ascaris worm. An additional 68 worms were collected from 60 human hosts in Kenyan villages where pig husbandry is rare. Notably, the majority of these worms (63/68) possessed mitochondrial genomes that clustered closer to the pig parasite Ascaris suum than to A. lumbricoides. Comparative phylogenomic analyses identified over 11 million nuclear-encoded SNPs but just two distinct genetic types that had recombined across the genomes analyzed. The nuclear genomes had extensive heterozygosity, and all samples existed as genetic mosaics with either A. suum-like or A. lumbricoides-like inheritance patterns supporting a highly interbred Ascaris species genetic complex. As no barriers appear to exist for anthroponotic transmission of these 'hybrid' worms, a one-health approach to control the spread of human ascariasis will be necessary.

Journal article

Milne G, Fujimoto C, Bean T, Peters HJ, Hemmington M, Taylor C, Fowkes RC, Martineau HM, Hamilton CM, Walker M, Mitchell JA, Leger E, Priestnall SL, Webster JPet al., 2020, Infectious causation of abnormal host behavior: toxoplasma gondiiand Its potential association with dopey fox syndrome, Frontiers in Psychiatry, Vol: 11, Pages: 1-16, ISSN: 1664-0640

The apicomplexan parasite Toxoplasma gondii, the causative agent of toxoplasmosis, can infect all warm-blooded animals. T. gondii can subtly alter host behaviors—either through manipulation to enhance transmission to the feline definitive host or as a side-effect, or “constraint,” of infection. In humans, T. gondii infection, either alone or in association with other co-infecting neurotropic agents, has been reliably associated with both subtle behavioral changes and, in some cases, severe neuropsychiatric disorders, including schizophrenia. Research on the potential impact of T. gondii on the behavior of other long-lived naturally infected hosts is lacking. Recent studies reported a large number of wild red foxes exhibiting a range of aberrant behavioral traits, subsequently classified as Dopey Fox Syndrome (DFS). Here we assessed the potential association between T. gondii and/or other neurotropic agents with DFS. Live, captive foxes within welfare centers were serologically tested for T. gondii and, if they died naturally, PCR-tested for vulpine circovirus (FoxCV). Post-mortem pseudo-control wild foxes, obtained from pest management companies, were PCR-tested for T. gondii, FoxCV, canine distemper virus (CDV), canine adenovirus type (CAV)-1 and CAV-2. We also assessed, using non-invasive assays, whether T. gondii–infected foxes showed subtle behavioral alterations as observed among infected rodent (and other) hosts, including altered activity, risk, and stress levels. All foxes tested negative for CAV, CDV, CHV, and DogCV. DFS was found to be associated with singular T. gondii infection (captives vs. pseudo-controls, 33.3% (3/9) vs. 6.8% (5/74)) and singular FoxCV infection (66.7% (6/9) vs. 11.1% (1/9)) and with T. gondii/FoxCV co-infection (33.3% (3/9) vs. 11.1% (1/9)). Overall, a higher proportion of captive foxes had signs of neuroinflammation compared to pseudo-controls (66.7% (4/6) vs. 11.1% (1/9)). Consistent with behavioral changes

Journal article

Zou H-Y, Yu Q-F, Qiu C, Webster JP, Lu D-Bet al., 2020, Meta-analyses of Schistosoma japonicum infections in wild rodents across China over time indicates a potential challenge to the 2030 elimination targets, PLOS NEGLECTED TROPICAL DISEASES, Vol: 14, ISSN: 1935-2735

Journal article

Léger E, Borlase A, Fall CB, Diouf ND, Diop SD, Yasenev L, Catalano S, Thiam CT, Ndiaye A, Emery A, Morrell A, Rabone M, Ndao M, Faye B, Rollinson D, Rudge JW, Sène M, Webster JPet al., 2020, Prevalence and distribution of schistosomiasis in human, livestock, and snail populations in northern Senegal: a One Health epidemiological study of a multi-host system., The Lancet Planetary Health, Vol: 4, Pages: e330-e342, ISSN: 2542-5196

BACKGROUND: Schistosomiasis is a neglected tropical disease of global medical and veterinary importance. As efforts to eliminate schistosomiasis as a public health problem and interrupt transmission gather momentum, the potential zoonotic risk posed by livestock Schistosoma species via viable hybridisation in sub-Saharan Africa have been largely overlooked. We aimed to investigate the prevalence, distribution, and multi-host, multiparasite transmission cycle of Haematobium group schistosomiasis in Senegal, West Africa. METHODS: In this epidemiological study, we carried out systematic surveys in definitive hosts (humans, cattle, sheep, and goats) and snail intermediate hosts, in 2016-18, in two areas of Northern Senegal: Richard Toll and Lac de Guiers, where transmission is perennial; and Barkedji and Linguère, where transmission is seasonal. The occurrence and distribution of Schistosoma species and hybrids were assessed by molecular analyses of parasitological specimens obtained from the different hosts. Children in the study villages aged 5-17 years and enrolled in school were selected from school registers. Adults (aged 18-78 years) were self-selecting volunteers. Livestock from the study villages in both areas were also randomly sampled, as were post-mortem samples from local abattoirs. Additionally, five malacological surveys of snail intermediate hosts were carried out at each site in open water sources used by the communities and their animals. FINDINGS: In May to August, 2016, we surveyed 375 children and 20 adults from Richard Toll and Lac de Guiers, and 201 children and 107 adults from Barkedji and Linguère; in October, 2017, to January, 2018, we surveyed 386 children and 88 adults from Richard Toll and Lac de Guiers, and 323 children and 85 adults from Barkedji and Linguère. In Richard Toll and Lac de Guiers the prevalence of urogenital schistosomiasis in children was estimated to be 87% (95% CI 80-95) in 2016 and 88% (82-95) in 2017-

Journal article

Webster JP, Neves MI, Webster BL, Pennance T, Rabone M, Gouvras AN, Allan F, Walker M, Rollinson Det al., 2020, Parasite population genetic contributions to the schistosomiasis consortium for operational research and evaluation within Sub-Saharan Africa, American Journal of Tropical Medicine and Hygiene, Vol: 103, Pages: 80-91, ISSN: 0002-9637

Analyses of the population genetic structure of schistosomes under the “Schistosomiasis Consortium for Operational Research and Evaluation” (SCORE) contrasting treatment pressure scenarios in Tanzania, Niger, and Zanzibar were performed to provide supplementary critical information with which to evaluate the impact of these large-scale control activities and guide how activities could be adjusted. We predicted that population genetic analyses would reveal information on a range of important parameters including, but not exclusive to, recruitment and transmission of genotypes, occurrence of hybridization events, differences in reproductive mode, and degrees of inbreeding, and hence, the evolutionary potential, and responses of parasite populations under contrasting treatment pressures. Key findings revealed that naturally high levels of gene flow and mixing of the parasite populations between neighboring sites were likely to dilute any effects imposed by the SCORE treatment arms. Furthermore, significant inherent differences in parasite fecundity were observed, independent of current treatment arm, but potentially of major impact in terms of maintaining high levels of ongoing transmission in persistent “biological hotspot” sites. Within Niger, naturally occurring Schistosoma haematobium/Schistosoma bovis viable hybrids were found to be abundant, often occurring in significantly higher proportions than that of single-species S. haematobium infections. By examining parasite population genetic structures across hosts, treatment regimens, and the spatial landscape, our results to date illustrate key transmission processes over and above that which could be achieved through standard parasitological monitoring of prevalence and intensity alone, as well as adding to our understanding of Schistosoma spp. life history strategies in general.

Journal article

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