Monogeneans rely on firm attachment to often flexible and uneven surfaces and are renowned for their effective posterior attachment structures in the form of adhesives, clamps, hamuli and suckers. Polystomatids do not secrete adhesives and do not have clamps. While only some have hamuli, all have suckers in the adult form. Three different types of haptoral suckers have been described based on basic morphology but have never been studied in depth. Using enzyme digestion and light (differential interference contrast), confocal and scanning electron microscopy, we examined representatives and propose four sucker types. Haptoral sucker Type I are symmetrical soft, flexible, cup- to disk-shaped suckers and are found in all polystomes infecting frogs and salamanders. Type II suckers are symmetrical soft, flexible, cup-shaped suckers with a hollow continuous skeletal ring and no other skeletal elements. They are found in species of Nanopolystoma Du Preez, Wilkinson et Huyse, 2008 infecting caecilians. Type III suckers are symmetrical firm, cup-shaped suckers with elaborate skeletal elements that contribute to a secure grip on the host tissue. This type of sucker is found in all polystomes infecting freshwater turtles and the common hippopotamus. Type IV suckers are asymmetrical with an elaborate series of long, thin sclerites with terminal spines or hooks. This type of sucker is only known from Concinnocotyla australensis (Reichenbach-Klinke, 1966) infecting the Australian lungfish. These different sucker types are crucial for the survival of polystomatid flatworms within their respective microhabitats.
Toxoplasmosis is one of the world's most prevalent zoonoses. The causative agent, Toxoplasma gondii (Nicolle et Manceaux, 1908) is a facultative heteroxenic, polyxenic apicomplexan protist. There are several potential pathways of transmission within and between host species. Most infections with T. gondii result from close contact with pets/cats, ingestion of tissue cysts in undercooked meat of infected animals, and oocysts from food or water contaminated by feline faeces. Recently, epidemiological studies have shown that T. gondii infection plays a prominent role in the pathogenesis of several psychiatric disorders. This report reviews the association between T. gondii infection and patients with psychiatric disorders, particularly schizophrenia, depressive disorders and bipolar disorders.
Canningia spinidentis gen. et sp. n. infects the fir bark beetle Pityokteines spinidens Rtt. in Austria. The pathogen attacks mainly the fat body, Malpighian tubules, the muscles and the connective tissue of larvae and adults, and the gonads of adults. The development is haplokaryotic, with single spores. Spores are short tubular, uninucleate, with globular anchoring disc inserted subapically, laterally, in a depression of the endospore wall. Polar filament is isofilar, with 5/6 coils. Polaroplast is composed of two lamellar parts of different density. A new genus Canningia gen. n. is proposed based on differences in ultrastmc-tures of spores from Unikaryon Canning, Barker, Hammond et Nicholas, 1974.
Ligula intestinalis (Linnaeus, 1758) is a tapeworm parasite with a worldwide distribution that uses a wide variety of fish species as its second intermediate host. In the present study, we investigated the prevalence and population genetic structure of plerocercoids of L. intestinalis in five common cyprinoid species, roach Rutilus rutilus (Linnaeus), freshwater bream Abramis brama (Linnaeus), white bream Blicca bjoerkna (Linnaeus), bleak Alburnus alburnus (Linnaeus), and rudd Scardinius erythrophthalmus (Linnaeus), collected in six water bodies of the Czech Republic (Milada, Most, Medard, Jordán, Římov and Lipno). Of the six study sites, the highest frequency of parasitism was recorded in Lake Medard (15%). The overall prevalence rate among the species was as follows: roach > rudd ≥ freshwater bream > bleak > white bream. Two mitochondrial genes (cytb and COI) were used to compare the population genetic structure of parasite populations using selected samples from the five fish species. The results of the phylogenetic analysis indicated that all populations of L. intestinalis were placed in Clade A, previously identified as the most common in Europe. At a finer scale, haplotype network and PCoA analyses indicated the possible emergence of host specificity of several mtDNA haplotypes to the freshwater bream. Moreover, pairwise Fixation indices (FST) revealed a significant genetic structure between the parasite population in freshwater bream and other host species. Parasite populations in roach not only showed the highest rate of prevalence but also depicted a maximum number of shared haplotypes with populations from bleak and rudd. Our results suggest that recent ecological differentiation might have influenced tapeworm populations at a fine evolutionary scale. Thus, the differences in prevalence between fish host species in different lakes might be influenced not only by the parasite's ecology, but also by its genetic diversity.
Cats are important hosts for different zoonotic parasites that can be hazardous to human health. To date, few studies have attempted to identify the factors affecting parasitic infections in shelter animals. This study aims to analyse the presence of endoparasites in shelter cats in Tartu, Estonia, and identify factors affecting endoparasite prevalence and intensity. The risk factors considered were age, location (urban vs rural cats) and time spent in shelter. In total, 290 faecal samples were collected from cats at an animal shelter in 2015-2016 and investigated for endoparasites using the concentration flotation technique. In total, 138 shelter cats (47.6%) were infected with endoparasites and their overall prevalence was: Toxocara cati (36.6%), Cystoisospora spp. (12.4%), Taeniidae gen. sp. (4.1%), Toxoplasma gondii/Hammondia hammondi (3.4%), Eucoleus aerophilus (2.1%), Cryptosporidium spp. (2.1%), Ancylostoma sp. (0.7%) and Giardia sp. (0.7%). Coinfections occurred in 38 cats (13.1%) most frequently of T. cati and Cystoisospora spp. (4.5%), Cystoisospora spp. and T. gondii/H. hammondi (2.1%). Where species identification of cestode and nematode samples was not possible according to morphology, genetic analysis of the mitochondrial cox1 gene was carried out. DNA was successfully analysed for 6 out of 13 samples that required genetic identification, revealing Ancylostoma tubaeforme in one nematode sample and Hydatigera taeniaeformis in five cestode samples. Cats from rural areas had significantly higher endoparasite prevalence than cats from urban areas. Helminth prevalence decreased to some extent due to anthelmintic treatment in cats available for adoption (held ≥15 days in the shelter), whereas the prevalence of infection with protists increased significantly in these animals. It is important to note that the analysis revealed lower infection intensity for quarantine cats (held 1-14 days in the shelter) compared with cats available for adoption. The relatively high prevalence of endoparasites (including zoonotic) in shelter cats ready for adoption suggests that current anthelminthic procedures require improvements.
In the present study, we have investigated the role of antimalarial drug halofantrine (HF) in inducing the sterile protection against challenges with sporozoites of the live infectious Plasmodium yoelii (Killick-Kendrick, 1967) in Swiss mice malaria model. We observed that during the first to third sequential sporozoite inoculation cycles, blood-stage patency remains the same in the control and chemoprophylaxis under HF drug cover (CPS-HF) groups. However, a delayed blood-stage infection was observed during the fourth and fifth sporozoite challenges and complete sterile protection was produced following the sixth sporozoite challenge in CPS-HF mice. We also noticed a steady decline in liver stage parasite load after 3th to 6th sporozoite challenge cycle in CPS-HF mice. CPS-HF immunisation results in a significant up-regulation of pro-inflammatory cytokines (IFN-γ, TNF-α, IL-12 and iNOS) and down-regulation of anti-inflammatory cytokines (IL-10 and TGF-β) mRNA expression in hepatic mononuclear cells (HMNC) and spleen cells in the immunised CPS-HF mice (after 6th sporozoite challenge) compared to control. Overall, our study suggests that the repetitive sporozoite inoculation under HF drug treatment develops a strong immune response that confers protection against subsequent challenges with sporozoites of P. yoelii.
The life-history of Mazocraes alosae Hermann, 1782 on one of its hosts, the Pontic shad Alosa immaculata Bennett, is described for the first time. This anadromous fish, which occurs off the coast of the Crimea and migrates from the Black Sea to the Sea of Azov and into the River Don for spawning, was studied throughout its migration and during all seasons. It is demonstrated that the period of reproduction of this monogenean is significantly longer than that reported for the population in the Caspian Sea, lasting from April to November with a peak in April-May, and continues both in the sea and the river. Experiments showed that water salinity does not limit the development of the eggs or the hatching of the oncomiracidia. Our data reveal that the abundance of M. alosae is not determined by the size or sex of mature fish and that shad of less than two years old can also be infected with this monogenean, although less frequently than older fish. The direction of the migration of A. immaculata, either from the Black Sea to the Sea of Azov and into the rivers or in the opposite direction, does not influence the number of monogeneans present on the host. The main factor affecting the dynamics of the abundance of this monogenean is season, and, as has been indicated previously in the Caspian Sea basin, there is a synchronisation between the parasite's life-history and both the host's spawning behaviour and the duration of its migration.
Chloromyxum leydigi Mingazzini, 1890, the type species of Chloromyxum Mingazzini, 1890, is redescribed based on material found in the gall bladder of the cartilaginous fish Torpedo marmorata Risso collected from the Portuguese Atlantic coast and its sporogonic development is described. Plasmodia and mature spores were floating free in the bile. Plasmodia are polysporic and highly polymorphic in shape and organization. Mature spores are spherical to subspherical with a pointed anterior end, measuring 12.3 ± 0.5 μm in length and 9.0 ± 0.5 μm in width. The spore wall is composed of two asymmetric shell valves, each bearing 4-5 elevated surface ridges. A bundle of 40-50 tapering caudal filaments extends from the basal portion of the shell valves. Four pyriform equal-sized polar capsules, measuring about 5.3 × 3.2 μm, are observed at the same level in the anterior pole of the spores, each containing a polar filament coiled in 8-9 (rarely 10) turns. Spore morphology, tissue tropism, host species and sequences of the SSU rRNA gene supported species identification. Since its discovery, this species has been dubiously reported from several cartilaginous hosts, namely due to the poor description of its features.
Four new species of Ceratomyxa Thélohan, 1892 are described from the gall bladders of fishes collected off Lizard Island, Australia. These species are characterised using a combination of morphometric and molecular data. Ceratomyxa bartholomewae sp. n. is described from Hyporhamphus dussumieri (Valenciennes) (family Hemirhamphidae); C. koieae sp. n. is described from Sphyraena forsteri Cuvier (family Sphyraenidae); C. pantherini sp. n. is described from Bothus pantherinus (Rüppell) (family Bothidae) and C. reidi sp. n. is described from Chaetodon vagabundus Linnaeus (family Chaetodontidae). A fifth species from Zebrasoma veliferum (Bloch) (family Acanthuridae) is also reported but due to limited material is not formally described here.
The impacts of aquatic invasive species vary from the population to ecosystem level most strikingly through modifications to native communities, often leading to a decline in native species. A primary impact mechanism is competitive displacement of native by invasive species through resource partitioning. However, the trophic interactions between native and invasive species occupying the same habitat remain poorly understood, particularly at the early stages of invasion. This study used stable isotope analysis of two co-occurring populations of invasive topmouth gudgeon, Pseudorasbora parva and native Caucasian dwarf goby, Knipowitschia caucasica in a highly productive shallow lake to characterize overlap of potential trophic niches. The trophic niches of both species were divergent, with no overlap. Mixing models suggest some inter-specific dietary differences. The trophic niche of the Caucasian dwarf goby was slightly and non-significantly larger than that of topmouth gudgeon. These results suggest that when introduced outside of their natural range, topmouth gudgeon might integrate into new fish communities via the exploitation of resources that are underexploited by native fishes, which could also explain the high invasion success of the species.