Interspecific interactions between parasites sharing the same host are often antagonistic; the presence of one species decreases the number of individuals or negatively affects both the distribution and reproduction of the other species. Antagonistic interactions between co-infecting parasites may translate into direct competition or interactive segregation, but elements of both may be present. Potential interactions between two acanthocephalan species, Pomphorhynchus laevis and Acanthocephalus anguillae, were studied in the field in two of their natural fish definitive hosts. There was no evidence for competitive exclusion between P. laevis and A. anguillae. However, a negative interaction was found for the first time in the field between these two species. Based on the analysis of parasite abundance and total biomass using a static regression approach, I found that the abundance and total biomass of parasite was also limited by host characteristics. These results are consistent with previous laboratory studies on competition between P. laevis and A. anguillae.

The morphogenesis and the distribution along the digestive tract of Trichostrongylus retortaeformis(Zeder, 1800) (Nematoda) were studied in detail in one of its natural hosts, Oryctolagus cuniculus. Worm-free rabbits were each infected with T. retortaeformis larvae and were killed at 12 h post-infection (HPI) and on each day from 1 to 15 days post-infection (DPI). The distribution of worm populations along the small intestine was assessed. At the different dates of infection, more than 80% of the population was recovered from the first third of the intestine with more than 50% occuring in the first 30 cm. For each date, morphological descriptions of the different stages of the life cycle were also provided. In addition, adult worms collected from naturally infected rabbits from France were redescribed.

Bivitellobilharzia nairi was first recorded from an Indian elephant (Elephas maximus) in Berlin. Infections with this parasite have become increasingly important in E. maximus maximus populations in Sri Lanka. The present work is the first morphological description of this schistosome from Sri Lanka. A number of adult worms were recovered from a dead Asian elephant near the elephant orphanage, Pinnawala, in Sri Lanka. The observed clinical features of the infected elephant included emaciation, subventral oedema and anaemia. Post-mortem results indicated that the liver was enlarged and adult schistosomes were found in the blood vessels of the liver parenchyma. The total number of worms recovered from a portion of the liver was 129,870, which is an average of 22 worms per 100 g of liver. The present study uses both light microscopic and scanning electron microscope (SEM) techniques for the morphological and topographical characterization of this parasite and to permit comparison with other species of schistosomes. Morphologically, these worms correspond very well to the description of B. nairi by Dutt & Srivastava (1955). Moreover, it is clear that B. nairi is a distinctive species easily differentiated from other schistosomes. The SEM study of the tegument of male worms shows that the surface of B. nairi is smoother than in other schistosomes.

Global programmes to eliminate lymphatic filariasis (GPELF) require mapping, monitoring and evaluation using filarial antigen diagnostic kits. To meet this objective, a functional single-chain fragment variable (ScFv) specific for filarial Wuchereria bancrofti SXP-1 (Wb-SXP-1) antigen was constructed for the diagnosis of active filarial infection, an alternative to the production of complete antibodies using hybridomas. The variable heavy chain (VH) and the variable light chain (kappa) (Vκ) genes were amplified from the mouse hybridoma cell line and were linked together with a flexible linker by overlap extension polymerase chain reaction (PCR). The ScFv construct (Vκ–Linker–VH) was expressed as a fusion protein with N-terminal His tag in Escherichia coli and purified using immobilized metal affinity chromatography (IMAC) without the addition of reducing agents. Immunoblotting and sandwich enzyme-linked immunosorbent assay (ELISA) were used to analyse the antigen binding affinity of purified ScFv. The purified ScFv was found to recognize recombinant and native Wb-SXP-1 antigen in microfilariae (Mf)-positive patient sera. The affinity of ScFv was comparable with that of the monoclonal antibody. The development of recombinant ScFv to replace monoclonal antibody for detection of filarial antigen was achieved. The recombinant ScFv was purified, on-column refolded and its detection ability validated using field samples.

During the summer and autumn of 1994, 1995 and 1996, 406 juvenile herring caught off the Swedish west coast were examined for parasites. Amongst those found was the digenean Pseudobacciger harengulae, which represents new host and locality records for this parasite. Pseudobacciger harengulae has been reported from several species of clupeiformes, mostly from tropical and temperate regions of the Atlantic, Pacific and Indian Oceans. The morphology of P. harengulae is described and compared with earlier descriptions of P. harengulae and P. manteri. The possible relationships between P. harengulae and P. manteri are discussed and the validity of the P. manteri is questioned. Most of the specimens (75%) of P. harengulae were found in the pyloric caeca and the remainder (25%) in the intestine.

Spiny mice, Acomys cahirinus dimidiatus, inhabiting the wadis close to St Katherine in the mountains of the Sinai peninsula, were trapped and their helminth parasites were studied. Sixty one mice provided faeces for analysis and 27 were killed and autopsied. Six species of helminths were recorded (the spirurid nematodes, Protospirura muricola (74.1%) and Mastophorus muris (11.1%), the oxyuroid nematodes, Dentostomella kuntzi (59.3%), Aspiculuris africana (3.7%), and Syphacia minuta (3.7%) and the hymenolepidid cestode Rodentolepis negevi (18.5%)). The spirurids were the dominant species present, accounting for up to 0.87% of total host body weight. Analysis of worm weights and lengths suggested that transmission had been taking place in the months preceding our study. No sex difference in the prevalence or abundance of spirurids was detected. Significant differences were identified in the abundance of total nematode burdens and the mean helminth species richness between the three wadis which provided multiple captures of mice. There was also a marked effect of host age on both parameters. A highly significant positive correlation between spirurid egg counts and total worm biomass indicated that non-invasive techniques based on egg counts could be used to quantify worm burdens and when this technique was applied to a larger sample size (n = 61), a significant difference between sites but no host sex or age effects were detected for spirurid faecal egg counts. The data suggest that there are differences between helminth component communities infecting spiny mice in different neighbouring wadis, a hypothesis which will be explored further through our continuing studies in the Sinai.

The Cyathocotylidae Mühling, 1898 is a family of primitive diplostomoid trematodes important for understanding the evolution of the superfamily Diplostomoidea. However, cyathocotylids remain poorly studied with the use of molecular techniques. In this study we sequenced the 5.8S + ITS2 region, 28S rRNA, and cox1 genes of two cyathocotylid species and obtained new morphological data on them. We propose Georduboisia nom. nov. instead of the preoccupied name Duboisia Szidat, 1936 (junior homonym of Duboisia Stremme, 1911). Adults of Georduboisia cf. teganuma (Ishii, 1935) and Paracoenogonimus ovatus Katsurada, 1914 were collected from fish-eating birds in the south of the European part of Russia. Georduboisia cf. teganuma was very similar to G. teganuma but differed from it in the shape of the testes. The 28S rRNA gene dataset provided the best-resolved phylogeny of the Cyathocotylidae to date. In the phylogram based on partial sequences of this gene, P. ovatus was close to members of Holostephanoides Dubois, 1983, Neogogatea Chandler & Rausch, 1947 and Gogatea Szidat, 1936. Georduboisia cf. teganuma clustered with members of Cyathocotyle Mühling, 1896 and Holostephanus Szidat, 1936. Phylogenetic analysis based on the 5.8S + ITS2 dataset showed that adults of P. ovatus examined in our study were conspecific with the metacercariae from the musculature of fish collected in Hungary and Italy. It also revealed probable misidentifications of larvae and adults of cyathocotylids whose sequences are deposited in GenBank NCBI.

Interspecific interactions between parasites sharing the same host are often antagonistic; the presence of one species decreases the number of individuals or negatively affects both the distribution and reproduction of the other species. Antagonistic interactions between co-infecting parasites may translate into direct competition or interactive segregation, but elements of both may be present. Potential interactions between two acanthocephalan species, Pomphorhynchus laevis and Acanthocephalus anguillae, were studied in the field in two of their natural fish definitive hosts. There was no evidence for competitive exclusion between P. laevis and A. anguillae. However, a negative interaction was found for the first time in the field between these two species. Based on the analysis of parasite abundance and total biomass using a static regression approach, I found that the abundance and total biomass of parasites was also limited by host characteristics. These results are consistent with previous laboratory studies on competition between P. laevis and A. anguillae.

Clinostomidae is a diverse family of digenean parasitizing fish-eating birds as adults and fishes as metacercariae. The species composition, within the genus Clinostomum has been steadily increasing in recent years. In Argentina, four named species of Clinostomum have been documented, accompanied by four metacercariae representing distinct genetic lineages whose adults have not been identified. This study focused on examining clinostomids in three fish species – Australoheros scitulus (ASI), Cichlasoma dimerus (CDIM), and Pimelodella laticeps (PLA) – at various localities in Argentina. We conducted both morphological and molecular characterizations of the Clinostomum metacercariae collected from these fish species. Molecular phylogenetic analyses using COI mtDNA were performed to determine the placement of these metacercariae within the clinostomid phylogenetic tree. Clinostomum ASC represents a distinct lineage, morphologically distinguishable from other sequenced metacercariae due to its body shape (widest anteriorly and becoming slender towards the posterior end); this lineage was found to be closely related to C. caffarae. While Clinostomum CDIM and Clinostomum PLA exhibited morphological differences, they clustered together genetically with metacercariae reported in previous studies as Clinostomum L3 and Clinostomum CVI. This outcome, coupled with a low genetic distance (0 to 3%), suggests that they are conspecific with metacercariae found in fish across Mexico, Costa Rica, and Argentina. In light of the extensive diversity of fish species in Argentine freshwater ecosystems (over 500 species), and considering the relatively constrained extent of prior investigations, the anticipation of unearthing additional Clinostomum species or lineages is plausible.

Taenia solium is a zoonotic parasite that causes taeniasis and cysticercosis in humans (as final hosts) and cysticercosis in pigs (as intermediate hosts). The Russian Federation (RF) is traditionally considered as endemic for this zoonosis. However, the epidemiological data on T. solium infection have not been reviewed for the past 20 years, in which time dynamic economical and societal changes have occurred in the RF. The aim of this systematic review was to analyse the status of T. solium infection in RF in the 2000–2019 period. A literature search was conducted, which collected published articles, grey literature and official data on the epidemiology of T. solium taeniasis and cysticercosis in the RF published from 2000. From a total of 2021 articles and 24 official reports originally returned by the search, data were extracted from 12 full text articles and 11 official reports. Taenia solium taeniasis was continuously reported in the RF between 2000 and 2019, with a tenfold decrease in the incidence, from 0.2 per 100,000 population in 2000 to 0.023/100,000 in 2019. Also, the number of administrative units where taeniasis was detected continuously decreased. Cysticercosis in pigs had a declining trend after 2006. In conclusion, although decreasing, T. solium infection is still endemic in several regions and suspected to be endemic in most of the RF.

A new species of the genus Stephanostomum is described for the southeastern Gulf of Mexico based on morphological and nucleotide evidence. Stephanostomum minankisi n. sp. infects the intestine of the dusky flounder Syacium papillosum in the Yucatan Continental Shelf, Mexico (Yucatan Peninsula). Sequences of the 28S ribosomal gene were obtained and compared with available sequences of the other species and genera of the families Acanthocolpidae and Brachycladiidae from GenBank. A phylogenetic analysis was conducted, including 39 sequences, 26 of which represented 21 species and six genera of the family Acanthocolpidae. The new species is characterized by the absence of circumoral spines and spines on the tegument. Nonetheless, scanning electron microscopy consistently revealed the pits of 52 circumoral spines distributed in a double row with 26 spines each, and forebody spined. Other distinctive features of this species are testes in contact (sometimes overlapping), the vitellaria running along the body lateral fields to the mid-level of the cirrus-sac, pars prostatica and ejaculatory duct similar in length, and uroproct present. The phylogenetic tree showed that the three species found as parasites of dusky flounder (the new adult species and two in metacercaria stages) were grouped into two different clades. S. minankisi n. sp. was the sister species of Stephanostomum sp. 1 (Bt = 56) and formed a clade with S. tantabiddii, supported by high bootstrap values (100).

Although several records now exist of the occurrence of Capillaria (Hepaticola) hepatica (Bancroft, 1893) as a natural infection of the wild rabbit the attempts which have been made to infect this host with eggs obtained from an infection in the rat have not been completely successful. Nishigori (1925) states that although this parasite can infect the rabbit and shew some development it does not reach maturity, while Saito (1925), in the English account of his paper given in The Japan Medical World states that “In the rabbit the larva might develop into maturity and cause pathological changes but do not multiply.”

Pseudocorynosoma constrictum (Van Cleave, 1918) is a polymorphid acanthocephalan that attaches to the digestive tract of waterfowl to complete its life cycle, causing severe histological damage to its definitive avian hosts. In the present study, we present a histopathological analysis of the lesions that P. constrictum induced in the layers of the ileum of the blue-winged teal Anas discors. The results revealed that worms insert the attachment structures into the inner gut muscular layer, which causes substantial swelling, haemorrhaging and necrosis in the tissue near the parasite's proboscis. We also observed that the number of parasites attached to the tissue can obstruct the intestinal lumen; in the most serious case, we observed more than 30 parasites penetrating completely the walls of the bird intestine.

A taxonomic review was performed on cestodes of the genus Neoskrjabinolepis Spassky, 1947 that parasitize different species of Sorex shrews in different regions of the northern Palearctic and in the Nearctic (Alaska, USA). Information on Palearctic Neoskrjabinolepis cestodes published in various articles is summarized. An overview of the geographical distribution of the Neoskrjabinolepis species is also presented. Currently, the genus includes 17 species. In the European part of the Palearctic, four species of the genus are registered; in the Asian part, 13 species; and on the American continent (Seward Peninsula, Alaska, USA), two species. Descriptions, illustrations, and differential diagnoses are given for a new species of Neoskrjabinolepis, i.e. N. paradoxa n. sp., which was found in shrews Sorex unguiculatus Dobson and S. caecutiens Laxmann on Sakhalin Island. A unique feature of the new species is irregularly alternating genital pores in the uterus series in the strobila. Amended new differential features (positioning of the uterus relative to osmoregulatory canals and alternation of genital pores) of genus diagnosis and an identification key for Neoskrjabinolepis spp. are presented.

Nematode spicules vary in shape and size even between closely related species and, therefore, constitute key characters in nematode taxonomy for distinguishing between species. Spicules are seldom measured on fresh specimens, but rather at some time after extraction from culled hosts and after a period of preservation of the worms in chemical fixatives or by freezing. We carried out two experiments to assess the effects of freezing in Hanks’ balanced salt solution, 70% or 80% ethanol and 10% formalin (both of the latter at room temperature and after storage at −80°C) on spicule length of Heligmosomoides bakeri at two time intervals after extraction from mice (Experiment 1, one and four weeks; Experiment 2, one and four months). In Experiment 1, no significant differences were detected, although there was some variation between treatments and over time. In Experiment 2, spicule length varied significantly between treatments and over time, the greatest shrinkage being in 80% ethanol and the least in 10% formalin. However, overall variation in spicule length was very limited, accounting for no more than 5.03% change in length over time and 4.95% between treatments at any of the periods of assessment. Therefore, while whole nematodes can shrivel and shrink in preservatives, making many measurements unreliable, our data indicated that spicule lengths are very little changed by preservation techniques over time, and so spicule length remains as a reliable taxonomic character.

Two species of the genus Aporcella, one new and one previously known, collected from cultivated fields in Iran are studied. Description, morphometrics, illustrations (both line and microphotographs) and D2–D3 sequences are provided for Aporcella talebii sp. n., which is characterized by its 1.66–2.02-mm-long body, lip region offset by constriction and 15–17 μm broad, odontostyle 14–17.5 μm long, neck 412–484 μm long, pharyngeal expansion occupying 46–50% of total neck length, uterus simple and 1.6–2.0 times the corresponding body diameter long, V = 52–59, tail conical (40–50 μm, c = 37–47, c′ = 1.1–1.4) with a weak but perceptible dorsal concavity at the end and male absent. Morphometrics, microphotographs and D2–D3 sequences of Aporcella simplex are also presented, this being its first Asian record. Molecular analyses confirm the monophyly of the genus, its close relationship with other taxa lacking pars refringens vaginae and the polyphyly of Aporcelaimidae.

Tetraspanins are a superfamily of transmembrane proteins that in flatworms have structural roles in the development, maturation or stability of the tegument. Several tetraspanins are considered as potential candidates for vaccines or drugs against helminths. Monopisthocotylean monogeneans are ectoparasites of fish that are health hazards for farmed fish. The aim of this study was to identify in silico putative tetraspanins in the genomic datasets of four monopisthocotylean species. The analysis predicted and classified 40 tetraspanins in Rhabdosynochus viridisi, 39 in Scutogyrus longicornis, 22 in Gyrodactylus salaris and 13 in Neobenedenia melleni, belonging to 13 orthologous groups. The high divergence of tetraspanins made it difficult to annotate their function. However, a conserved group was identified in different metazoan taxa. According to this study, metazoan tetraspanins can be divided into 17 monophyletic groups. Of the 114 monogenean tetraspanins, only seven were phylogenetically close to tetraspanins from non-platyhelminth metazoans, which suggests that this group of proteins shows rapid sequence divergence. The similarity of the monopisthocotylean tetraspanins was highest with trematodes, followed by cestodes and then free-living platyhelminths. In total, 27 monopisthocotylean-specific and 34 flatworm-specific tetraspanins were identified. Four monogenean tetraspanins were orthologous to TSP-1, which is a candidate for the development of vaccines and a potential pharmacological target in trematodes and cestodes. Although studies of tetraspanins in parasitic flatworms are scarce, this is an interesting group of proteins for the development of new methods to control monogeneans.

Two new species belonging to two different families of the super-family Aphelenchoidea are described. The material was obtained from the roots of tobacco plants, Nicotiana tabacum.

The worms were killed by hot water, fixed in F.A.A. solution, cleared in 1% glycerine alcohol mixture and mounted in pure glycerine.

It has been, for some time, a recognised fact that intense eelworm infections are, in some instances, accompanied by only slight damage to the plants, while in other areas where the infection is much less intense, the plants show every symptom of “potato sickness” and the crop is a complete failure.

1. Nematobothrium labeonis n. sp. from the orbit of three species of Labeo is described.

2. The more recent literature relating to the classification of the genus is considered.

3. N. labeonis is contrasted with related species.