Search results for "Helminth"
showing 10 items of 363 documents
First Record of the Nematode Physaloptera squamatae in the Helminth Community of the Introduced Anole Anolis grahami (Polychrotidae) on Bermuda
2021
The gastrointestinal helminth communities of five populations of Anolis grahami, an introduced anole on Bermuda, were surveyed to determine the prevalence, abundance, and species diversity of parasites in these reptiles. Only three nematode species were found, Atractis scelopori, Parapharyngodon cubensis, and Physaloptera squamatae. This species, P. squamatae, is recorded for the first time in Anolis grahami on Bermuda, probably introduced through its arthropod intermediate host. The role of the host A. grahami as a “spillover” agent for these parasites is discussed.
Helminth infracommunities of a population of the Gran Canaria giant lizard Gallotia stehlini
2004
AbstractA survey of gastro-intestinal helminth communities of Gallotia stehlini (Sauria: Lacertidae) from Gran Canaria island (Canary Archipelago, Spain), was conducted to determine the prevalence, abundance and species diversity of intestinal parasites in these lizards. Pharyngodonid nematodes were the most common intestinal helminths, three species being Gallotia specialists. Helminth infracommunities of G. stehlini were rich and appear to be closer to the interactive end of the continuum isolationist–interactive helminth communities, according to the high values of helminth diversity. It is the first case of a saurian reptile showing this kind of diverse helminth infracommunity, produced…
The structure of parasite component communities in brackish water fishes of the northeastern Baltic Sea
2001
We used nestedness analysis to seek non-random patterns in the structure of component communities of metazoan parasites collected from 31 sympatric fish species from the northeastern Bothnian Bay, the most oligohaline area of the Baltic Sea. Only 8 marine parasite species were found among the 63 species recorded, although some marine fish species reproduce in the bay and others occasionally visit the area. Marine parasite species can utilize both freshwater and marine fish species as intermediate or final hosts, and marine fish can harbour freshwater parasite species. This exchange of parasite species between marine and freshwater fish has probably resulted from ecological factors acting ov…
Predicting the environmental suitability for onchocerciasis in Africa as an aid to elimination planning
2021
Recent evidence suggests that, in some foci, elimination of onchocerciasis from Africa may be feasible with mass drug administration (MDA) of ivermectin. To achieve continental elimination of transmission, mapping surveys will need to be conducted across all implementation units (IUs) for which endemicity status is currently unknown. Using boosted regression tree models with optimised hyperparameter selection, we estimated environmental suitability for onchocerciasis at the 5 × 5-km resolution across Africa. In order to classify IUs that include locations that are environmentally suitable, we used receiver operating characteristic (ROC) analysis to identify an optimal threshold for suitabil…
Platyzoan paraphyly based on phylogenomic data supports a noncoelomate ancestry of spiralia.
2014
Based on molecular data three major clades have been recognized within Bilateria: Deuterostomia, Ecdysozoa, and Spiralia. Within Spiralia, small-sized and simply organized animals such as flatworms, gastrotrichs, and gnathostomulids have recently been grouped together as Platyzoa. However, the representation of putative platyzoans was low in the respective molecular phylogenetic studies, in terms of both, taxon number and sequence data. Furthermore, increased substitution rates in platyzoan taxa raised the possibility that monophyletic Platyzoa represents an artifact due to long-branch attraction. In order to overcome such problems, we employed a phylogenomic approach, thereby substantially…
Independent host switching events by digenean parasites of cetaceans inferred from ribosomal DNA
2015
Cetaceans harbour a unique fauna of digeneans whose origin and relationships have sparked considerable debate during recent decades. Disparity in the species reported indicates that they do not share close affinities, but their unusual morphology has made their taxonomic identities and phylogenetic positions uncertain. Here we use sequence data to investigate the phylogenetic relationships of the main species of flukes infecting cetaceans. We sequenced the 18S, 28S and internal transcribed spacer 2 rDNA of digenean species representing all known families reported from cetaceans: Braunina cordiformis (Brauninidae), Ogmogaster antarcticus (Notocotylidae), Pholeter gastrophilus (Heterophyidae)…
Molecular phylogeny of species of Ligophorus (Monogenea: Dactylogyridae) and their affinities within the Dactylogyridae.
2012
The taxonomic framework of Ligophorus, monogenean specialists of the gills of grey mullets (Mugilidae), is evaluated and its interspecific relationships are assessed for the first time using molecular data. The position of Ligophorus within the paraphyletic Ancyrocephalinae is re-assessed based on newly sequenced species. Furthermore, the relationship between morphometric and genetic interspecific similarities is evaluated. Partial 28S and complete ITS1 rDNA sequences from representatives of 14 of the 16 nominal species of Ligophorus from the Mediterranean, Black and Azov Seas were analysed together with published sequences of members of the Dactylogyridae. The phylogenetic analyses of the …
Parasite specificity in Podarcis bocagei and P. carbonelli (Lacertidae) from NW Portugal: a host-parasite history
2015
Host parasite specificity is related to several factors including the type of life cycle of the parasite, the habitat occupied by both parasites and hosts, and the food habits of the hosts. In this work, gastrointestinal helminths in two congeneric lacertid lizards, Podarcis bocagei and Podarcis carbonelli living in sintopy, have been analysed. Out of four helminth species found, three of them, the trematode Brachylaima sp., the cestode Oochoristica gallica and the nematode Skrjabinelazia hoffmanni, have indirect life cycles while the nematode Spauligodon carbonelli has a direct life cycle. Heteroxenous helminths showed low host specificity whereas S. carbonelli may be placed at an intermed…
Real-Time Polymerase Chain Reaction for Detection of Schistosoma DNA in Small-Volume Urine Samples Reflects Focal Distribution of Urogenital Schistos…
2014
Schistosoma haematobium eggs and Schistosoma DNA levels were measured in urine samples from 708 girls recruited from 18 randomly sampled primary schools in South Africa. Microscopic analysis of two 10-mL urine subsamples collected on three consecutive days confirmed high day-to-day variation; 103 (14.5%) girls had positive results at all six examinations, and at least one positive sample was seen in 225 (31.8%) girls. Schistosoma-specific DNA, which was measured in a 200-μL urine subsample by using real-time polymerase chain reaction, was detected in 180 (25.4%) cases, and levels of DNA corresponded significantly with average urine egg excretion. In concordance with microscopic results, pol…
Estimating trematode prevalence in snail hosts using a single-step duplex PCR: how badly does cercarial shedding underestimate infection rates?
2014
Background: Trematode communities often consist of different species exploiting the same host population, with two or more trematodes sometimes co-occuring in the same host. A commonly used diagnostic method to detect larval trematode infections in snails has been based on cercarial shedding, though it is often criticized as inaccurate. In the present study we compare infection prevalences determined by cercarial emission with those determined, for the first time, by molecular methods, allowing us to quantify the underestimation of single and double infections based on cercarial emission. We thus developed a duplex PCR for two host-parasite systems, to specifically differentiate between sin…