• Assessment of the genetic relationship between Dictyocaulus species from Bos taurus and Cervus elaphus using complete mitochondrial genomic datasets

      Gasser, RB; Jabbar, A; Mohandas, N; Höglund, J; Hall, RS; Littlewood, T; Jex, AR (Springer Science and Business Media LLC, 2012-10-30)
      Background: Dictyocaulus species are strongylid nematodes of major veterinary significance in ruminants, such as cattle and cervids, and cause serious bronchitis or pneumonia (dictyocaulosis or “husk”). There has been ongoing controversy surrounding the validity of some Dictyocaulus species and their host specificity. Here, we sequenced and characterized the mitochondrial (mt) genomes of Dictyocaulus viviparus (from Bos taurus) with Dictyocaulus sp. cf. eckerti from red deer (Cervus elaphus), used mt datasets to assess the genetic relationship between these and related parasites, and predicted markers for future population genetic or molecular epidemiological studies. Methods: The mt genomes were amplified from single adult males of D. viviparus and Dictyocaulus sp. cf. eckerti (from red deer) by long-PCR, sequenced using 454-technology and annotated using bioinformatic tools. Amino acid sequences inferred from individual genes of each of the two mt genomes were compared, concatenated and subjected to phylogenetic analysis using Bayesian inference (BI), also employing data for other strongylids for comparative purposes. Results: The circular mt genomes were 13,310 bp (D. viviparus) and 13,296 bp (Dictyocaulus sp. cf. eckerti) in size, and each contained 12 protein-encoding, 22 transfer RNA and 2 ribosomal RNA genes, consistent with other strongylid nematodes sequenced to date. Sliding window analysis identified genes with high or low levels of nucleotide diversity between the mt genomes. At the predicted mt proteomic level, there was an overall sequence difference of 34.5% between D. viviparus and Dictyocaulus sp. cf. eckerti, and amino acid sequence variation within each species was usually much lower than differences between species. Phylogenetic analysis of the concatenated amino acid sequence data for all 12 mt proteins showed that both D. viviparus and Dictyocaulus sp. cf. eckerti were closely related, and grouped to the exclusion of selected members of the superfamilies Metastrongyloidea, Trichostrongyloidea, Ancylostomatoidea and Strongyloidea. Conclusions: Consistent with previous findings for nuclear ribosomal DNA sequence data, the present analyses indicate that Dictyocaulus sp. cf. eckerti (red deer) and D. viviparus are separate species. Barcodes in the two mt genomes and proteomes should serve as markers for future studies of the population genetics and/or epidemiology of these and related species of Dictyocaulus.
    • Detection of ascaridoid nematode parasites in the important marine food-fish Conger myriaster (Brevoort) (Anguilliformes: Congridae) from the Zhoushan Fishery, China

      Chen, H-X; Zhang, L-P; Gibson, David I.; Lü, L; Xu, Z; Li, H-T; Ju, H-D; Li, L (Springer Science and Business Media LLC, 2018-05-02)
      Background The whitespotted conger Conger myriaster (Brevoort) (Anguilliformes: Congridae) is an extremely marketable food fish, commonly consumed as sashimi or sushi in some Asian countries (i.e. Japan, Korea and China). Conger myriaster is also suspected as being an extremely important source of human anisakidosis. However, there is currently very little information on the levels of infection with ascaridoid nematode parasites in this economically important marine fish. The aims of the present study are to determine the species composition, prevalence and mean intensity of ascaridoid parasites of C. myriaster caught in the Zhoushan Fishery. Results A total of 1142 third-stage ascaridoid larvae were isolated from 204 C. myriaster. The overall prevalence of infection was 100% (mean intensity 5.6). Nine species of such larvae were accurately identified using integrative taxonomic techniques involving both morphological and genetic data; these included Anisakis pegreffii, A. typica and A. simplex (sensu stricto) × A. pegreffii, Hysterothylacium fabri, H. aduncum, H. sinense, H. amoyense, H. zhoushanense and Raphidascaris lophii. Although high levels of infection and species richness were revealed in C. myriaster, most of the ascaridoid parasites (1135 individuals) were collected from the body cavity and visceral organs of the fish and only seven individuals of A. pegreffii were found in the musculature. Conclusions This study represents the first report C. myriaster from the Zhoushan Fishery being heavily infected with third-stage ascaridoid larvae. Among the ascaridoid larvae parasitic in this fish, an important etiological agent of human anisakidosis, A. pegreffii (L3), represents the predominant species. The genus Hysterothylacium has the highest species richness, with H. fabri (L3) being the most prevalent species. This high level of infection of A. pegreffii (L3) in C. myriaster suggests a high risk of anisakidosis or associated allergies for people consuming raw or poorly cooked fish originating from this marine area. These findings provide important basic information on the occurrence and infection parameters of ascaridoid nematodes in this economically important marine fish. They also have significant implications for the prevention and control of human anisakidosis when conger eels from the Zhoushan Fishery are consumed.
    • Development of novel multiplex microsatellite polymerase chain reactions to enable high-throughput population genetic studies of Schistosoma haematobium

      Webster, BL; Rabone, M; Pennance, T; Emery, AM; Allan, F; Gouvras, A; Knopp, S; Garba, A; Hamidou, AA; Mohammed, KA; et al. (2015-12)
    • Discovery of a single male Aedes aegypti (L.) in Merseyside, England

      Harbach, RE; Dallimore, T; Hunter, T; Medlock, JM; Vaux, AGC; Strode, C (2017-12)
    • Diversity of Anopheles mosquitoes in Binh Phuoc and Dak Nong Provinces of Vietnam and their relation to disease

      Ngo, C; Dubois, G; Sinou, V; Parzy, D; Le, H; Harbach, RE; Manguin, S (2014)
    • Erratum to: Development of novel multiplex microsatellite polymerase chain reactions to enable high-throughput population genetic studies of Schistosoma haematobium

      Webster, BL; Rabone, M; Pennance, T; Emery, AM; Allan, F; Gouvras, A; Knopp, S; Garba, A; Hamidou, AA; Mohammed, KA; et al. (2015-12)
    • The increased sensitivity of qPCR in comparison to Kato-Katz is required for the accurate assessment of the prevalence of soil-transmitted helminth infection in settings that have received multiple rounds of mass drug administration

      Dunn, JC; PAPAIAKOVOU, MARINA; Han, KT; Chooneea, D; Bettis, AA; Wyine, NY; Lwin, AMM; Maung, NS; Misra, Raju; Littlewood, T; et al. (Springer Science and Business Media LLC, 2020-06-24)
      Background The most commonly used diagnostic tool for soil-transmitted helminths (STH) is the Kato-Katz (KK) thick smear technique. However, numerous studies have suggested that the sensitivity of KK can be problematic, especially in low prevalence and low intensity settings. An emerging alternative is quantitative polymerase chain reaction (qPCR). Methods In this study, both KK and qPCR were conducted on stool samples from 648 participants in an STH epidemiology study conducted in the delta region of Myanmar in June 2016. Results Prevalence of any STH was 20.68% by KK and 45.06% by qPCR. Prevalence of each individual STH was also higher by qPCR than KK, the biggest difference was for hookworm with an approximately 4-fold increase between the two diagnostic techniques. Prevalence of Ancylostoma ceylanicum, a parasite predominately found in dogs, was 4.63%, indicating that there is the possibility of zoonotic transmission in the study setting. In individuals with moderate to high intensity infections there is evidence for a linear relationship between eggs per gram (EPG) of faeces, derived from KK, and DNA copy number, derived from qPCR which is particularly strong for Ascaris lumbricoides. Conclusions The use of qPCR in low prevalence settings is important to accurately assess the epidemiological situation and plan control strategies for the ‘end game’. However, more work is required to accurately assess STH intensity from qPCR results and to reduce the cost of qPCR so that is widely accessible in STH endemic countries.
    • Mapping freshwater snails in north-western Angola: distribution, identity and molecular diversity of medically important taxa

      Allan, F; Sousa-Figueiredo, JC; Emery, AM; Paulo, R; Mirante, C; Sebastião, A; Brito, M; Rollinson, D (BMC & Springer Nature, 2017-10-10)
      This study was designed to determine the distribution and identity of potential intermediate snail hosts of Schistosoma spp. in Bengo, Luanda, Kwanza Norte and Malanje Provinces in north-western Angola. This is an area where infection with Schistosoma haematobium, causing urogenital schistosomiasis, is common but little is yet known about transmission of the disease. Angola has had a varied past with regard to disease control and is revitalising efforts to combat neglected tropical diseases.
    • The mitochondrial genome of Parascaris univalens - implications for a “forgotten” parasite

      Jabbar, A; Littlewood, T; Mohandas, N; Briscoe, AG; Foster, PG; Müller, F; von Samson-Himmelstjerna, G; Jex, AR; Gasser, RB (2014)
    • Molecular characterization and distribution of Schistosoma cercariae collected from naturally infected bulinid snails in northern and central Côte d’Ivoire

      Tian-Bi, Y-NT; Webster, BL; Konan, CK; Allan, F; Diakité, NR; Ouattara, M; Salia, D; Koné, A; Kakou, AK; Rabone, M; et al. (Springer Nature, 2019-03-19)
      Accurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and elimination. Cercariae emerging from infected snails cannot be precisely identified morphologically to the species level. We used molecular tools to clarify the distribution of the Schistosoma haematobium group species infecting bulinid snails in a large part of Côte d’Ivoire and confirmed the presence of interspecific hybrid schistosomes. Methods Between June 2016 and March 2017, Bulinus snails were sampled in 164 human-water contact sites from 22 villages of the northern and central parts of Côte d’Ivoire. Multi-locus genetic analysis (mitochondrial cox1 and nuclear ITS) was performed on individual schistosome cercariae shed from snails, in the morning and in the afternoon, for species and hybrid identification. Results Overall, 1923 Bulinus truncatus, 255 Bulinus globosus and 1424 Bulinus forskalii were obtained. Among 2417 Bulinus screened, 25 specimens (18 B. truncatus and seven B. globosus) shed schistosomes, with up to 14% infection prevalence per site and time point. Globally, infection rates per time point ranged between 0.6 and 4%. Schistosoma bovis, S. haematobium and S. bovis × S. haematobium hybrids infected 0.5%, 0.2% and 0.4% of the snails screened, respectively. Schistosoma bovis and hybrids were more prevalent in B. truncatus, whereas S. haematobium and hybrid infections were more prevalent in B. globosus. Schistosoma bovis-infected Bulinus were predominantly found in northern sites, while S. haematobium and hybrid infected snails were mainly found in central parts of Côte d’Ivoire. Conclusions The data highlight the necessity of using molecular tools to identify and understand which schistosome species are transmitted by specific intermediate host snails. The study deepens our understanding of the epidemiology and transmission dynamics of S. haematobium and S. bovis in Côte d’Ivoire and provides the first conclusive evidence for the transmission of S. haematobium × S. bovis hybrids in this West African country. Trial registration ISRCTN, ISRCTN10926858. Registered 21 December 2016; retrospectively registered (see: http://www.isrctn.com/ISRCTN10926858)
    • New insights into the genetic diversity of Schistosoma mansoni and S. haematobiumin Yemen

      Sady, H; Al-Mekhlafi, HM; Webster, BL; Ngui, R; Atroosh, WM; Al-Delaimy, AK; Nasr, NA; Chua, KH; Lim, YAL; Surin, J (2015-12)
    • Pooling as a strategy for the timely diagnosis of soil-transmitted helminths in stool: value and reproducibility

      PAPAIAKOVOU, MARINA; Wright, J; Pilotte, N; Chooneea, D; Schär, F; Truscott, JE; Dunn, JC; Gardiner, I; Walson, JL; Williams, SA; et al. (Springer Science and Business Media LLC, 2019-09-16)
      Background The strategy of pooling stool specimens has been extensively used in the field of parasitology in order to facilitate the screening of large numbers of samples whilst minimizing the prohibitive cost of single sample analysis. The aim of this study was to develop a standardized reproducible pooling protocol for stool samples, validated between two different laboratories, without jeopardizing the sensitivity of the quantitative polymerase chain reaction (qPCR) assays employed for the detection of soil-transmitted helminths (STHs). Two distinct experimental phases were recruited. First, the sensitivity and specificity of the established protocol was assessed by real-time PCR for each one of the STHs. Secondly, agreement and reproducibility of the protocol between the two different laboratories were tested. The need for multiple stool sampling to avoid false negative results was also assessed. Finally, a cost exercise was conducted which included labour cost in low- and high-wage settings, consumable cost, prevalence of a single STH species, and a simple distribution pattern of the positive samples in pools to estimate time and money savings suggested by the strategy. Results The sensitivity of the pooling method was variable among the STH species but consistent between the two laboratories. Estimates of specificity indicate a ‘pooling approach’ can yield a low frequency of ‘missed’ infections. There were no significant differences regarding the execution of the protocol and the subsequent STH detection between the two laboratories, which suggests in most cases the protocol is reproducible by adequately trained staff. Finally, given the high degree of agreement, there appears to be little or no need for multiple sampling of either individuals or pools. Conclusions Our results suggest that the pooling protocol developed herein is a robust and efficient strategy for the detection of STHs in ‘pools-of-five’. There is notable complexity of the pool preparation to ensure even distribution of helminth DNA throughout. Therefore, at a given setting, cost of labour among other logistical and epidemiological factors, is the more concerning and determining factor when choosing pooling strategies, rather than losing sensitivity and/or specificity of the molecular assay or the method.
    • Praziquantel coverage in schools and communities targeted for the elimination of urogenital schistosomiasis in Zanzibar: a cross-sectional survey

      Knopp, S; Person, B; Ame, SM; Ali, SM; Muhsin, J; Juma, S; Khamis, IS; Rabone, M; Blair, L; Fenwick, A; et al. (2016-12)
    • A review of the mosquito species (Diptera: Culicidae) of Bangladesh

      Irish, SR; Al-Amin, HM; Alam, MS; Harbach, RE (2016-12)
    • Significant variance in genetic diversity among populations of Schistosoma haematobium detected using microsatellite DNA loci from a genome-wide database

      Glenn, TC; Lance, SL; McKee, AM; Webster, BL; Emery, AM; Zerlotini, A; Oliveira, G; Rollinson, D; Faircloth, BC (Springer Nature, 2013)
      Background Urogenital schistosomiasis caused by Schistosoma haematobium is widely distributed across Africa and is increasingly being targeted for control. Genome sequences and population genetic parameters can give insight into the potential for population- or species-level drug resistance. Microsatellite DNA loci are genetic markers in wide use by Schistosoma researchers, but there are few primers available for S. haematobium. Methods We sequenced 1,058,114 random DNA fragments from clonal cercariae collected from a snail infected with a single Schistosoma haematobium miracidium. We assembled and aligned the S. haematobium sequences to the genomes of S. mansoni and S. japonicum, identifying microsatellite DNA loci across all three species and designing primers to amplify the loci in S. haematobium. To validate our primers, we screened 32 randomly selected primer pairs with population samples of S. haematobium. Results We designed >13,790 primer pairs to amplify unique microsatellite loci in S. haematobium, (available at http://www.cebio.org/projetos/schistosoma-haematobium-genome). The three Schistosoma genomes contained similar overall frequencies of microsatellites, but the frequency and length distributions of specific motifs differed among species. We identified 15 primer pairs that amplified consistently and were easily scored. We genotyped these 15 loci in S. haematobium individuals from six locations: Zanzibar had the highest levels of diversity; Malawi, Mauritius, Nigeria, and Senegal were nearly as diverse; but the sample from South Africa was much less diverse. Conclusions About half of the primers in the database of Schistosoma haematobium microsatellite DNA loci should yield amplifiable and easily scored polymorphic markers, thus providing thousands of potential markers. Sequence conservation among S. haematobium, S. japonicum, and S. mansoni is relatively high, thus it should now be possible to identify markers that are universal among Schistosoma species (i.e., using DNA sequences conserved among species), as well as other markers that are specific to species or species-groups (i.e., using DNA sequences that differ among species). Full genome-sequencing of additional species and specimens of S. haematobium, S. japonicum, and S. mansoni is desirable to better characterize differences within and among these species, to develop additional genetic markers, and to examine genes as well as conserved non-coding elements associated with drug resistance.