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The importance of small-scale heterogeneity in local factors which overrides that of larger-scales factors, suggest that local factors play a major role in determining the richness and prevalence of larval digeneans in intertidal gastropods. The restricted distribution of the snail Heleobia australis along a 500 m transect in Cangrejo creek (Mar Chiquita, Argentina) provides a good opportunity to test the assumption that a study at spatial scale of 100s meters can detect spatiotemporal fluctuations of a larval digenean assemblage. To analyze that, 3600 specimens of H. australis were collected seasonally during the year 2011. A quantitative variation and a space-time interaction between sampling points and seasons of the year for the total prevalence of larval digeneans and snail’s densities were found, as well as a positive correlation with abiotic factors. These results revealed that the fluctuations in the community of larval digeneans of the snail H. australis can be detected at small spatial scale, using its natural distribution of 500 m. This study also highlights the importance of seasonality as a factor that must be considered in studies focused on the search for patterns structuring the communities of larval digeneans, at medium and large scales.
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The reasons for helminth infections in hosts

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A maximum capacity of the host to parasites is very diverse so intensive infections (hiperinfections) are noticed repeatedly. The reasons for their occurrence can be divided based on the factors related to the biology and ecology of hosts: age, body size, food habits, anatomical and behavioral factors, monoxenous life cycle of parasites, environmental changes, contamination of the environment by the dispersion forms of parasites and new parasite-host relationships.
Echinostomatidae (Trematoda) is the largest family within the class Trematoda. Members of this family have been studied for many years in relation to their utility as basic research models in biodiversity and systematics and also as experimental models in parasitology since they offer many advantages. Echinostomes have contributed significantly to numerous developments in many areas studied by parasitologists and experimental biologists. In this review, we examine the history of the echinostomebased studies from the beginnings to the present. For this purpose, we have divided the history of echinostomes into four periods (i.e. 18th and 19th centuries, first half of the 20th century, second half of the 20th century and the late 20th and 21th century) according to the types of studies performed in each of them. Moreover, we also briefly review the history of echinostome infections in humans.
This study describes the assemblage of ectoparasitic bat flies, their hosts, and parasitism rates in an Atlantic Forest area in southern Brazil. Bats were captured monthly for one year at two sites. We captured 95 bats belonging to nine species, but only Artibeus lituratus, Artibeus fimbriatus, Sturnira lilium (Phyllostomidae) and Myotis nigricans (Vespertilionidae) were found to be parasitized. The bat flies collected were: Streblidae — Paratrichobius longicrus (on A. lituratus) and Megistopoda aranea (on A. lituratus and A. fimbriatus), Megistopoda proxima (on S. lilium); Nycteribiidae — Basilia andersoni (on M. nigricans). Artibeus fimbriatus and S. lilium showed the highest values of parasite prevalence (60 and 35.7%, respectively) and mean intensities (1.9 and 2.1, respectively). Only two parasitized individuals of A. lituratus were found, resulting in the lowest local rate of parasite prevalence (2.6%) and mean intensity (1.0). This low rate may result from the use of ephemeral roosts in the area. The high values of frequency and number of flies per host on A. fimbriatus and S. lilium in relation to other studies could be explained by the low richness of bat flies here, and in turn, by low competition among fly species per host.
The host-parasite relationship of the post-infection tissue resident and migratory stages of Uncinaria stenocephala are areas, which have received very little attention to-date. In the present experiments cellular and serum antibody responses were evaluated in mice infected percutaneously with infective larvae of the nematode. Significant eosinophil infiltration was observed in the skin at the site of infection. The number of these cells increased significantly (p<0.01) and dramatically at the site of the first infection (abdomen) within 24 h of exposure to the second dose of larvae which was administered at a different site (back). A clear IgE response of mice to somatic and surface antigens of L3 was observed. There was no further increase in IgE to the somatic antigen preparations following challenge, but a significantly higher concentration of IgE reactivity to surface antigens was detected 14 days after challenge. A short-lived, IgM, IgG and IgA response to the somatic antigens was also detected.
A review of the fleas and lice of the Nearctic chipmunks indicates that North American chipmunks, Neotarnias and Tamias, have had separate histories; and that one has not been derived directly from the other. The western chipmunks (Neotarnias) have in common a species assemblage of sucking lice and fleas, and the single eastern species, Tamias striatus (Linnaeus, 1758), has distinctive species of fleas which do not generally occur on other small mammals; none of the lice or fleas on T. striatus occcurs on the western chipmunks. This dichotomy of distribution of external parasites on these chipmunks indicates a very long separation of the hosts, and could not occur if one group had been directly derived from the other. Chipmunks in western North America, on the basis of the molecular evidence and distribution of sucking lice and fleas, are most logically placed in the genus Neotarnias. Such an arrangement is consistent with the morphological, molecular, and parasitological evidence, and suggests a plausible history and relationship of the three groups of chipmunks. The fossil distribution of North American chipmunks indicates an early movement from Asia in the Oligocene, and a scarcity or absence of chipmunks from the middle Miocene until the Pleistocene. Both Tamias striatus and species of Neotarnias are probably a product of two Pleistocene movements across the Bering connection.
The modern classification of trombiculid mites from the family Trombiculidae (Acariformes: Parasitengona) is briefly reviewed on the subfamily and tribe level based on the larval characters. Some taxonomical and evolutionary aspects are briefly discussed. The family Trombiculidae is divided into four subfamilies: Leeuwenhoekiinae — Apoloniinae — Trombiculinae — Gahrliepiinae, from which Leeuwenhoekiinae should be placed at the base and Gahrliepiinae at the top of phylogenetic tree. Host-parasite relationships of trombiculid larvae are examined from the point of view that host-parasite specificity is low in trombiculids. Some physiological questions with respect to the realization of the life strategy of trombiculids are considered.
The present study was conducted on bats from different locations in Turkey. Of 33 bats, belonging to 10 species, 10 individuals (30.3%) of four species were infected with gamasine mites. Fifty-three mites belonging to 2 families (Spinturnicidae and Macronyssidae) were collected. The spinturnicid Spinturnix myoti (Kolenati) was the most abundant species (27 specimens) and only recorded n Myotis nattereri (Kuhl). The species Steatonyssus periblepharus (Kolenati) and the genera Steatonyssus, Macronyssus and Ancystropus are reported from Turkey for the first time, while new host and distributional data are presented.
At present the nematode genus Rhabdochona Railliet, 1916 (Rhabdochonidae) comprises 92 possibly valid species, mostly intestinal parasites of freshwater fishes in all zoogeographical regions. Because of the absence of any phylogenetic studies using molecular methods in this nematode group, an attempt to evaluate affinities among these parasites and their zoogeography on the basis of morphological features and host-parasite relationships has been carried out. Only true definitive hosts should be considered for such evaluation. It appears that, during the evolution of Rhabdochona spp., there occur an increase in the number of anterior prostomal teeth, loss of lateral alae, the right spicule attains a boat-like shape and a dorsal barb develops on its distal tip, and the distal tip of the left spicule attains gradually a more complex structure; the eggs with a smooth surface are considered to be more primitive. Nematodes of this genus most probably originated in the region of present southern Asia at the beginning of Tertiary. Closest to the initial type appear to be members of the subgenus Globochona Moravec, 1972, from which lineages leading to the subgenera Globochonoides Moravec, 1975, Rhabdochona Railliet, 1916 and Sinonema Moravec, 1975 can be derived. The morphology of Rhabdochona spp. indicate a close relationship between the Palaearctic fauna of these nematodes with the Nearctic species, and the Oriental fauna with the Ethiopian fauna. The Neotropical species can be derived from Nearctic members of the subgenus Rhabdochona; the latter probably penetrated, along with leuciscine hosts into North America from Palaearctic Eurasia at the end of Tertiary. The distribution of Palaearctic species of Rhabdochona corresponds to faunistical complexes in the conception of ichthyologists.
A cladistic reconstruction of phylogenetic relationships between species of the feather mite family Syringobiidae was carried out. The maximum parsimony and neighbor-joining analyses were based on 201 external morphological characters of 65 syringobiid species (two species represented by 2 morphotypes each) and 4 species of pterolichid and ptiloxenid outgroups. The MP analysis produced 2 equally most parsimonious trees that were phylogenetically consistent and topologically very similar to the single tree reconstructed by NJ procedure. The results confirmed the monophyly of the family and monophyly of most syringobiid genera. The generic status of Limosilichus was weakly supported. Intergeneric relationships were most stable and well supported in the basal part of the tree (Plutarchusia-Paidoplutarchusia, Leptosyringobia, Grenieria, Thecarthra) with the exception of the position of the genus Raineria. All remaining species were placed in a large monophyletic clade with weaker statistical support for its internal composition. The present studies revealed the Magimeliinae as a sistergroup of Syringobiidae, a relationship that is discordant with the hitherto prevailing hypothesis. The cospeciation hypothesis was strongly supported statistically as one of the main factors in the current distribution of syringobiid mites on the hosts. However, other evolutionary events including at least four instances of host-switching have also contributed into the contemporary observed host-syringobiid associations. Only among the Laridae have all lineages of Syringobiidae diverged in parallel with host birds and represent members of the original acarofauna. In contrast, most of the syringobiid acarofauna of shore birds (Scolopacida and Charadrioidea) had ancestors on the Laridae and secondarily cospeciated after switching from this host group onto new hosts. The reconciliation results for syringobiid mites were compared with the patterns shown by other commensal mites inhabiting the same hosts - subfamily Avenzoariinae. In Syringobiidae the number of cospeciations was significantly smaller and the contribution of sorting events was significantly greater than in Avenzoariinae. Differences in distribution patterns on hosts (prevalence and density) of these two taxa were probably responsible for the significant differences in importance of particular evolutionary events observed in both taxa. The differences in distribution patterns of Syringobiidae and Avenzoariinae may be related to different degrees of virulence of each taxon. The cospeciation analysis has also allowed reinterpretation of morphological features occurring in many Syringobiidae that are typical of mites inhabiting the vane’s surface. The adaptations are most probably apomorphic reversals due to these syringobiids secondarily reoccupying this microhabitat from the quill environment.
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