A factorial experiment involving the presence and absence of three factors: steam sterilization (S), infection with some three million eggs and larvae of Heterodera rostochiensis per pot (H), and injection of 10 ml. of D-D per pot (D), the factors applied in that order, was carried out to ascertain the effects on the growth of 40 potato plants in pots containing 15 Kg. of soil.

In the event, the D-D was lethal to the great, majority of eelworms, so that treatments labelled (hd) and (hsd) were effectively reduced to (d) and (sd). This fact greatly complicated the analysis, but nevertheless enabled certain conclusions to be drawn. The use of this factorial design may be criticised in the face of this antagonistic action between, two of the factors. Nevertheless, the effects of H and D acting together on the plants was a subject of interest; the real fault in design lay in using too high a concentration of D-D, or in not using a series of concentrations. The fact that the concentration used was too high emerged from the experiment and was not known beforehand.

In 1839 Diesing described Stephanurus dentatus from the kidney of the pig. His description was incorrect in two important particulars, viz.— in stating that only one spicule was present and that the vulva was in the middle of the body instead of posteriorly. These errors, although corrected by Verril in 1870 and Louise Taylor in 1899, still persist, and it was on account of this that Drabble, in 1922, basing his diagnosis on a faulty text-book description, claimed that the Kidney worm of swine in New South Wales was generally distinct from Stephanurus dentatus. This worm he called Sclerostomum renium, n. sp.

Numerous attempts have been made in the past to induce the eggs of Ascaris suum to hatch outside the body of the host. Extra-corporeal hatching has been observed under a variety of conditions by different workers. Kondo (1920, 1922), Asada (1921) and others record hatching in water, charcoal and sand cultures. Wharton (1915) states that hatching will occur in alkaline digestive juices, while Martin (1913) records a similar phenomenon in pancreatic fluid. Many different explanations have been offered to explain this hatching. Wharton suggested that the interaction of algae and sand might have some effect. Ohba (1923), who found that hatching would occur in 0·2% hydrochloric acid and 0·2% sodium carbonate believed that extra-corporeal hatching was limited to very old cultures of eggs. Many workers are of the opinion that some stimulus normally present in the digestive tract is necessary for hatching.

The gastrointestinal helminth parasites of 170 common wallaroos or euros, Osphranter robustus (Gould), collected from all mainland states in which the species occurs as well as the Northern Territory, are presented, including previously published data. A total of 65 species of helminths were encountered, including four species of anoplocephalid cestodes found in the bile ducts and small intestine, and 61 species of strongylid nematodes, all but two of which occurring in the stomach, and with the remainder occurring in the terminal ileum, caecum and colon. Among the mainland subspecies of O. robustus, 52 species of helminths were encountered in O. r. robustus, compared with 30 species in O. r. woodwardi and 35 species in O. r. erubescens. Of the parasite species encountered, only 17 were specific to O. robustus, the remaining being shared with sympatric host species. Host-specific species or species occurring in O. robustus at a high prevalence can be classified as follows: widely distributed; restricted to northern Australia; restricted to the northern wallaroo, O. r. woodwardi; found only in the euro, O. r. erubescens; found essentially along the eastern coast of Australia, primarily in O. r. robustus; and species with highly limited regional distributions. The data currently available suggest that the acquisition of a significant number of parasites is due to co-grazing with other macropodids, while subspeciation in wallaroos as well as climatic variables may have influenced the diversification of the parasite fauna.

The aim of this study was to evaluate the association between eosinophils in ascites and the diagnosis of intestinal anisakidosis in patients with peritoneal signs on physical examination. We reviewed retrospectively 16 patients diagnosed with intestinal anisakidosis, evaluated between 2012 and 2015. All patients had ingested raw anchovies. The analysis of ascites fluid in ten of these patients was compared with that of 15 patients with ascites and other abdominal pathology (except liver cirrhosis). All patients had an increased number of white blood cells in the ascites fluid. The eosinophil count was significantly higher in patients with intestinal anisakidosis (P < 0.01). All patients had a good outcome. Increased eosinophils in ascites fluid is strongly associated with the diagnosis of intestinal anisakidosis.

Diaphanocephalus galeatus collected from the small intestine of the lizard Dracaena paraguayensis in the Pantanal wetlands, State of Mato Grosso do Sul, Brazil, is redescribed. Genetic characterization and observations using scanning electron microscopy (SEM) were performed for the first time. The vouchers of D. galeatus and the type specimens of its congeners, deposited in the Coleção Helmintológica do Instituto Oswaldo Cruz (CHIOC), were consulted. Light and SEM observations revealed several undescribed features of D. galeatus, i.e. structure of the cephalic end and of the buccal capsule, position and morphology of deirids, presence of phasmids in females and presence of unpaired papilla on the membranous projection that covers the genital cone in males. After observation of the specimens deposited in the helminthological collection, D. jacuruxi is considered a synonym of D. galeatus, and D. diesingi, despite its incomplete description, is tentatively retained as valid due to the poor condition of the type material. The results also indicated low host specificity of D. galeatus, contradicting previous assertions. Genetic comparisons using patristic distances and phylogenetic trees generated from sequences of the 28S rRNA nuclear gene indicated that D. galeatus is closer to the taxa within Ancylostomatoidea and Strongyloidea than any lineage of Metastrongyloidea or Trichostrongyloidea. However, most of the nodal supports were low. Based on the genetic and morphological characterization, the validity of D. galeatus was confirmed. These data may serve for further comparative approaches for different populations of the parasite, from different hosts in different geographical areas, mitigating taxonomic confusions.

For the first time the development of the excretory system Levinseniella brachysoma metacercariae (Trematoda: Microphallidae) obtained experimentally from Gammarus oceanicus has been described. The bladder wall of 8-day post-infection (P.I.) larvae consists of a syncytium covered with microvilli. Its cytoplasm contains well-developed rough endoplasmic reticulum (RER), free ribosomes, small oval dense mitochondria and numerous large membrane-bounded (about 5 μm in diameter) spherical granules. Later the size of the excretory bladder and the number of nuclei and RER cisternae increases. The large spherical granules disappear completely but spherical dense bodies (up to 4 μm in diameter) devoid of limiting membranes appear. The bladder lining forms thick columnar projections directed towards its lumen. Accumulations of microlamelli occur only on the lumen surface between adjacent projections. By the 42nd day P.I. the bladder wall has two separate components: the columnar projections and the syncytium between them.

To determine the minimum effective dose of praziquantel against Hymenolepis diminuta in rats, 5.0 mg/kg, 2.5 mg/kg, 1.0 mg/kg, 0.5 mg/kg, 0.1 mg/kg, or 0.05 mg/kg praziquantel were given to each of five experimentally infected rats in six groups. Faecal samples from each rat were examined for worms on day 10. Based on the results of faecal examination and autopsy, the minimum effective dose of praziquantel against Hymenolepis diminuta in rats was determined to be 0.5 mg/kg.

We present the results of our studies of the helminth fauna and the diet of the black-legged kittiwake (Rissa tridactyla Linnaeus, 1758) in the Gorodetskiy bird colonies on the Rybachiy Peninsula (Murman coast of the Barents Sea) carried out in 2006–2008 and in 2018–2020. We did not find any noticeable changes in the species diversity of the helminth fauna of the kittiwakes, the proportion of the dominant parasite species and the values of most quantitative infection indices between the two study periods. At the same time, there was a marked decrease in the mean abundance of the dominant cestode species (Alcataenia larina Krabbe, 1869 and Tetrabothrius erostris Loennberg, 1889) in 2018–2020 as compared to 2006–2008. The changes in parasitology of birds found in our study appear to be largely determined by fluctuations of abiotic conditions (increased water and air temperature) and the state of the food supply (size structure of the zooplankton) in the study area.

A checklist of larval digeneans parasitising molluscs from inland waters of Argentina is presented here. Based on the bibliographical survey of 113 scientific articles and nine theses published between 1930 and 2021, 213 digeneans were found, which were distributed within 13 superfamilies and 35 families. The parasites were identified in 102 locations, encompassing eight of the sixteen biogeographical provinces in Argentina. Digeneans were found in 34 mollusc species (31 gastropods and three bivalves) belonging to 17 genera. The available data are presented for each digenean species, and included host information, localities, prevalence values, type of habitat, life cycle information (natural or experimental host), and information on material and genetic sequences deposited in repositories. Only 21.1% of individuals were identified to species level, and 8.5% to genus level. In addition, the genetic sequences of only 10 species (4.7%) were available at GenBank. This survey constitutes the first checklist of parasitic helminths in molluscs from inland waters of Argentina.

Histochemical tests were done on newly excysted metacercariae and worms recovered from an abnormal host (rat) and the definitive host (dog) for some oxidoreductases, phosphatases and glycosidases. The results demonstrate that rat worms have enzymatic distribution and intensities more similar to those of metacercariae than to adult worms from dogs. Ultracytochemical examination of acid and alkaline phosphatase and Mg-ATPase activity was also carried out. Acid phosphatase activity occurred exceptionally in the excretory bladder and caeca of dog worms. No activity was observed in rat worms except for lysosomal granules in the tegument. Alkaline phosphatase activity was exhibited in the excretory bladder in both dog and rat worms. Mg-ATPase activity occurred in the tegument and parenchymal cells in dog worms and in the excretory bladder in rat worms. In metacercariae, little or no reaction for these enzymes was present except for Mg-ATPase activity on the excretory ducts. These observations, together with the histochemical results, indicate that metabolic activity in rat worms is higher than in metacercariae although it is strongly reduced compared with dog worms.

Fertile eggs of Toxocara pteropodis, passed in the faeces of juvenile flying-foxes, were ovoid to spheroid in shape with a diameter range of 80–110 µm. The shell was often seen to comprise 4 layers: a fine inner lipid layer, a thicker clear chitinous layer, an equally thick outer vitelline layer and a pitted outermost, proteinaceous uterine layer of variable thickness. Infertile eggs were less uniform in shape and generally did not have well-defined shell layers, the formation of which is triggered by sperm penetration of the oocyte. The eggs of this species are bulkier than those of related ascaridoids, apparently because of a thicker external coat which, while not providing mechanical strength, is thought to protect against desiccation. Scanning electron microscopical findings suggest that the outer layer is not applied directly by uterine cells, but forms by the gradual deposition of secretions in the uterine lumen, regardless of whether the oocyte has been fertilized.

The course of infection of chickens experimentally infected with C. nilesi suggested an immune response against the microfilariae. Autopsy findings of 6 experimentally infected chickens are given. In a chicken which received 32 infective larvae, when the peripheral blood was microfilaria negative for a period of 10 days, autopsy revealed 2 live active female and 3 live active male adult worms. These, when implanted in a clean 3 week old experimental chicken, produced a peripheral microfilaraemia for a further 63 days. When no peripheral microfilariae were detected for a period of 17 days, the recipient chicken was autopsied and microfilariae were found in the lung impression smears, although none of the implanted adult worms were found.

The morphology, structure and nocturnal subperiodicity of the microfilariae are described.

A case of human infection with Physaloptera causing an abscess in the neck of a patient in Hyderabad is recorded. The structure of one of the worms recovered, a female, is described and compared with that of other species recorded from mammals in India, but in the absence of the male it is not possible to determine the species.

Williams and Chaytor (1966) reported the presence of encysted strigeid trematode larvae on the muscles and liver of Epiplatys sexfasciatus and E. senegalensis collected from a stream at Hastings, Sierra Leone. Out of 253 fishes examined 89 or 35% were infected with the parasite.

The parasites when fed to day-old chicks or cattle egrets gave rise to adults which were identified as Posthodiplostomutn nanum Dubois, 1937.

de Man (1880) described the species Tylenchus macrophallus, obtained from pasture soil, and in a later publication (1884) gave a fuller account of it with drawings. Reasons are given later in the present paper for the removal of this species to the genus Paratylenchus. Micoletzky (1921) established the genus Paratylenchus containing but one species, namely, P. bukowinensis, obtained from around grass roots near Czernowitz in Bukowina. The description was based on a single female specimen which was found only after mounting in glycerine. In spite of this, however, the distinctive characters of the genus were clearly indicated and are sufficiently marked to separate it from the nearly related genus Anguillulina. Cobb (1923) gave a detailed description of the anatomy of another species, also obtained from around grass roots, under the name of Paratylenchus nanus, which he considered might be synonymous with P. bukowinensis, and a brief account of an immature form which he called P. anceps but which very closely resembled his P. nanus. In the case of both of these forms only females were found.

1. Biomphalaria p. nairobiensis, B. p. ruppelli and B. s. tanganyicensis have been found to be moderately susceptible to S. rodhaini from Kenya. A. glabratus from Puerto Rico is partially susceptible to the parasite. However, B. s. sudanica, B. dlexandrina, A. glabratus (Puerto Rico, albino strain) are refractory to infection with the same parasite from Kenya.

2. The present results together with those of some previous investigators suggest the existence of geographical strains of S. rodhaini.

Adult stages of Euclinostomum heterostomum (Rudolphi, 1809) were collected from the oral cavity and oesophagus of Bulbicus ibis in Liberia, West Africa. Structural relationships within the trematodes are clarified. A prepharynx from the oral sucker leads to a well developed pharynx to which the intestinal caeca communicate via a bulb-shaped oesophagus. The origin and extent of gonadal ducts are described including a Laurer's canal, whose aperture is dorsal. A discussion of the characters previously used to differentiate species of Euclinostomum corroborates the views expressed by Ukoli (1996) that the genus consists of two distinct species, E. heterostomum (Rudolphi, 1809) and E. multacaecum Tubangui and Maslungan, 1935. E. shrjabini Kurashvili, 1948 is proposed as a synonym of E. heterostomum. A compilation of the range in measurements of the adult and metacercarial stages of E. heterostomum is presented in the form of a table.

Development of the infective metacercaria of Mesostephanus yedeae Dennis and Penner, 1971 included: (a) ceicarial penetration and encystment in striated muscles, brain, liver and eye of Poecilia reticulata Peters; (b) a quiescent phase of nine days when no observable morphological change occurred; (c) a period of morphogenesis when an adhesive organ and a posterior body segment were differentiated. The time required for development to the infective metacercaria was delayed by decreasing the temperature of the fish host environment. The quiescent phase exhibited the greatest effects resulting from lowered temperature. Radial muscles and glands of the adhesive organ originated from parenchymal beta cells. The posterior appendage issued as a dorso-posterior evagination of the metacercarial body. Effects of the metacercaria on host tissues resulted in formation of a fibrous capsule in striated muscles, a granulomatous-like response in liver tissue, and necrosis of nervous tissue of the retinal complex which terminated in blindness of the infected eye. Effects of the adhesive organ on duodenal villi of the definitive host included “tearing” of the lamina propria and “pinching off” of pieces of duodenal epithelium.

We evaluated the effect of carbendazim on non-target organisms using the parasite Chordodes nobilii as a test organism. The Gordiida act as a link between freshwater and terrestrial ecosystems; and C. nobilii, a neotropical representative species of this group, has been shown to be sensitive to other contaminants even at environmentally acceptable concentrations. The taxa susceptible to carbendazim, however, may not be adequately represented among the standard aquatic test species used in ecotoxicological risk assessment. Moreover, the autochthonous organisms in this area that could be used as bioindicators still need to be found. The aim of the present work was therefore to assess the susceptibility of the preparasitic stages of C. nobilii to noxious effects by carbendazim. The assay protocol consisted in 96- and 48-h acute exposures of early embryonic stages and larvae, respectively, to concentrations ranging from 10 to 360 μg/l. Embryonic development was not inhibited by carbendazim at any of the evaluated concentrations, but the infectivity of larvae emerging from the exposed eggs was significantly diminished. Larval survival rate was also affected at the lowest concentration assayed. Values of the mean inhibition concentration (IC50) were 7 and 11 μg/l for embryos and larvae, respectively. Compared to other freshwater organisms, C. nobilii can be considered a species moderately to highly susceptible to carbendazim. As the expected environmental concentrations of carbendazim range from 6.25 to 41.3 μg/l, C. nobilii could well be a species in danger when exposed to this fungicide.