The comparative efficiency of the percutaneous and per-oral routes of infection was studied in goats experimentally infected with Schistosoma bovis. The heaviest infection was obtained by the percutaneous route, but a relatively high parasite load was also achieved by the per-oral route, i.e., where goats were allowed to drink a cercarial suspension, volume of 0·9 to 1·7 litre per animal. Studies using radio-isotopically labelled cercariae were designed to clarify the cercarial penetration sites following uptake by drinking. Radioactivity could be demonstrated in the outer lips, buccal cavity, oesophagus and the reticulum, omasum and rumen. Highest counts were recorded in outer lips, reticulum and rumen constituting 41·2, 22·1 and 20·6%, respectively, of total radioactivity recovered. It is concluded that the per-oral infection route may play a larger role than hitherto anticipated in infection of ruminants, and possibly also in other mammals, with schistosomes. The epidemiological implications of the present findings are discussed.

The survival of first-stage larvae of a laboratory strain of Muellerius capillaris and of a natural multispecific infection (Neostrongylus linearis, Cystocaulus nigrescens, Protostrongylus rufescens) was studied for 10 to 12 day periods. The survival was estimated either on larvae in faeces or kept in tap water. Temperature (−18°C to 37°C) and desiccation were the ecological factors investigated. M. capillaris was the most tolerant to these factors but showed better survival at 4°C (and at − 18°C on one occasion). N. linearis survived better at 25°C or − 18°C and C. nigrescens at 4°C and − 18°C. Humidification of faeces was unfavourable to the latter species. All the species could stand desiccation of faeces up to 67% of dry-matter for M. capillaris or 82% for other species. Larval survival estimated for L1 in tap water was different from that estimated for larvae in faeces. The variation in resistance to unfavourable temperatures or moisture conditions may account partly for the geographical distribution of the species

The number of circulating haemocytes, the size of the haematopoietic organ, and the size of haemocyte capsules around the parasite were studied in M-line Biomphalaria glabrata snails exposed to 100 or 400 first-stage larvae of Angiostrongylus cantonensis. The number of haemocytes in exposed snails increased significantly at 1 day post-exposure, decreased to control value, and then increased again. The decrease in number of circulating haemocytes is probably due to the removal of cells from the circulation to participate in encapsulation of larvae. The majority of circulating haemocytes in M-line B. glabrata are fully-spread granulocytes, which increase significantly in number in snails following exposure to A. cantonensis larvae. However, populations of partially-spread granulocytes, round cells, hyalinocytes and miscellaneous haemocytes were relatively constant. The size of capsules around the parasite increased during the 42-day interval of the experiment. The haematopoietic organ increased in size in response to infection.

The material upon which this addition to the ever-growing genus Enlerobius is based, was collected from the cæcum and large intestine of two marmosets which died at the London Zoological Gardens during the winter of 1931–32. The material came to me in the course of the routine examination of Helminthological material from the Prosectorium, and as the genus is one of importance in relation to human hygiene, this species seems to the writer to merit a brief description.

All three genera of the Gastrodiscinae, namely, Gastrodiscus Leuckart, 1877, Homalogaster Poirier, 1883 and Gastrodiscoides Leiper, 1913 are shown to lack a true pars prostatica and cirrus pouch. The two last-mentioned have some part of the male ducts provided with cilia and all three possess papillae on the ventral surface; these papillae are demonstrated to have a very different structure in each of the three genera. These and the male ducts are described and the subfamily Gastrodiscinae and the genus Gastrodiscoides are redefined.

Gastrodiscoides hominis is recorded from a Rhesus monkey.

In the collection of nematodes assembled by Prof. R. T. Leiper in this department there are numerous examples of worms from game animals in different parts of the world. Amongst these the writer, in further study of the Œsophagostomes, has been privileged to examine bottles of some provisionally labelled Œsophagostomum, sp.? One lot was collected from the Roan antelope (Hippotragus equinus) by Dr. J. E. S. Old in Nyasaland, another was collected from the Wart Hog (Phacocærus æthiopicus) in Uganda by Prof. R. T. Leiper. The other bottle contained worms from the latter host collected in Northern Territory Gold Coast, by Dr. J. J. Simpson on two different occasions. A study of these specimens shows that they comprise three species new to science, and one species just recently described by Daubney (1924).

Elaphostrongylus cervi Cameron, 1931 was identified in six Cervus elaphus hispanicus sampled in Cuenca, central Spain. A total of 23 adult worms were found in the central nervous system with a mean of 3.8. Although E. cervi is reported to be widespread in cervids, this is the first time it has been recorded in Spanish red deer.

Infection with hydatid cysts of domestic animals slaughtered by private individuals and at the Government Central Slaughterhouse is recorded. Both fertile and non-fertile cysts were seen in the infected animals. The home slaughtered sheep seems to play an important role in the dissemination of the parasite and the life cycle of Echinococcus granulosus in the State of Kuwait is assumed to be sheep—dog—sheep.

Phasmarhabditis hermaphrodita is a parasitic nematode of terrestrial gastropods that has been formulated into a biological control agent for farmers and gardeners to kill slugs and snails. In order to locate slugs it is attracted to mucus, faeces and volatile cues; however, there is no information about whether these nematodes are attracted to snail cues. It is also unknown how wild isolates of P. hermaphrodita or different Phasmarhabditis species behave when exposed to gastropod cues. Therefore, we investigated whether P. hermaphrodita (commercial and wild isolated strains), P. neopapillosa and P. californica were attracted to mucus from several common snail species (Cepaea nemoralis, Cepaea hortensis, Arianta arbustorum and Cornu aspersum). We also examined whether snails (C. aspersum) collected from different locations around the UK differed in their attractiveness to wild isolates of P. hermaphrodita. Furthermore, we also investigated what properties of snail mucus the nematodes were attracted to, including hyaluronic acid and metal salts (FeSO4, ZnSO4, CuSO4 and MgSO4). We found that the commercial strain of P. hermaphrodita responded poorly to snail mucus compared to wild isolated strains, and C. aspersum collected from different parts of the UK differed in their attractiveness to the nematodes. We found that Phasmarhabditis nematodes were weakly attracted to all metals tested but were strongly attracted to hyaluronic acid. In a final experiment we also showed that pharmacological manipulation of cyclic guanosine monophosphate (cGMP) increased chemoattraction to snail mucus, suggesting that the protein kinase EGL-4 may be responsible for Phasmarhabditis sp. chemoattraction.

An account is given of the incidence of the abomasal parasites in the lambs of South-West Britain. Some 600 lambs were examined, and counts of the parasites were conducted in 100 cases.

It is suggested that to explain the constancy of infection with Ostertagia, and the great difference between these “healthy figures” and the pathogenic figures (10,000) of other authors, it is necessary to assume a resistance to the accumulation of the parasite present within the sheep.

It has been held for many years that the species of Syphacia found in the field mouse (Apodemus sylvaticus) and originally described by von Linstow (1884) under the name of Oxyuris stroma is the same as Syphacia obvelata (Rud., 1802)—a common parasite of rats and mice and occasionally found in man.

In a paper published in 1925, the writer described the anatomy of the adults of this parasite and amplified Schøyen's account of it. At the same time it was shown that infective material derived from Elymus arenarius could give rise to galls on the roots of barley and Poa annua. Kemner (1930) has quite recently shown experimentally that the parasite from barley can set up galls on E. arenarius and presented important data on the agricultural significance of the parasite in northern Sweden. Detailed information as to which is infective stage of the parasite and on its life-history have so far been lacking and in order to remedy this omission the writer made a number of observations and carried out certain cultural experiments during 1927 and in the months of July, August and September 1931. These latter were made possible by the arrival during July of a good supply of galled roots of Elymus arenarius received in a living condition.

First-stage larvae of pure strains of M. capillaris and N. linearis (Nematoda: Protostrongylidae) from goats were used to assess the influence of rapid desiccation on survival. M. capillaris survived desiccation of faeces better than N. linearis. The latter species was particularly susceptible to duration of storage after desiccation (0 to 10 days). Surviving larvae of desiccated batches of M. capillaris were less able to infect the land-snail Candidula intersecta. Resistance of first-stage larvae to desiccation is a key factor in infectivity and may partly account for the geographical distribution of the two species of protostrongylids.

Echinococcus granulosus is the causative agent of cystic echinococcosis, which has serious impacts on human and/or animal health, resulting in significant economic losses. Echinococcus granulosus comprises a number of intra-specific variants or strains at the genetic level. In Saudi Arabia, few studies were performed on genetic variations in Echinococcus species. Therefore, the present study aimed to investigate the phenotypic and genetic characterization of hydatid cysts harboured by sheep and camels in Al-Madinah Al-Munawarah. Samples of hydatid cysts were collected from local sheep (n = 25) and camels (n = 8). The morphological criteria of protoscoleces were investigated. To investigate the molecular characterization, random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR), single-stranded conformation polymorphism (SSCP) were carried out. DNA was extracted from individual fertile cysts and subjected to RAPD-PCR analysis (using five arbitrary primers) and PCR amplification of cytochrome c oxidase I (cox1) and 12S ribosomal ribonucleic acid (12S rRNA) genes. The PCR products were subjected to SSCP analysis for genetic discrimination in E. granulosus isolates. In addition, partially sequencing of the mitochondrial DNA cox1 genes was achieved for assessing the phylogenetic positions of collected isolates using some global published sequence data of cox1 genes. The rostellar hooks of camel and local sheep isolates show remarkable variability in their dimensions. Five distinct SSCP patterns were identified in the 12S rRNA gene, showing intraspecific variations in E. granulosus of camels and local sheep. Sequencing of (cox1) genes of both local sheep and camels exhibit high similarity with those of the same gene (E. granulosus sensu stricto) published in NCBI BLAST.

Reptiles, as well as other vertebrate groups, harbour a significant diversity of parasitic organisms, from nematodes and other helminths to viruses and bacteria. The Northeast is one of the richest regions in Brazil in terms of the reptile diversity, number of species and endemism. Parasites are diverse organisms and knowledge about the parasitic fauna of vertebrates is an important factor in understanding the ecological relationships between hosts and the environment. Studies on the parasitic fauna of reptiles in South America have increased in the past few years. The present review is a compilation of 122 studies published from 1924 to 2021. We present information on 101 species of reptiles from five groups (amphisbaenians, crocodile, testudines, snakes and lizards) and 183 parasitic taxa belonging to four phyla: Nematoda; Arthropoda; Platyhelminthes; and Acanthocephala. Nematodes were the most frequently recorded species. Lizards and snakes had more records of parasitism and higher levels of parasite richness and diversity. Ceará was the state with most studies and recorded cases of parasite–host association. The Caatinga and Atlantic Forest were the most investigated environments. The objective of this review was to contribute knowledge on the parasitic biodiversity in reptiles from Northeast Brazil, which may help identify gaps in our knowledge and guide future studies.

A certain amount of confusion still exists as to the terminology to be adopted in discussing the various stages in the life cycle of the nematoda. This appears to be largely due to a difference of opinion as to the termination of each stage.

After a larva has reached a certain size, it commences to change in form and completes this process by shedding its cuticle. This change in form is the lethargus. It may or may not immediately escape from the cast cuticle, but when it does, the ecdysis is complete. The form which emerges is morphologically identical with the form inside the cuticle after the completion of the lethargus.

This accordingly gives a double choice as to the exact end of the stage. It may be during the lethargus, when the morphology of the form is changing, or it may be at the moment when the larva leaves the cast cuticle. The interval between these periods is slight in some cases but is considerable in the case of the infective stage. As the physiological end of the stage seems to coincide with the lethargus, I have accordingly based my nomenclature on it.

Intraspecific diversity in parasites with heteroxenous life cycles is guided by reproduction mode, host vagility and dispersal, transmission features and many other factors. Studies of these factors in Digenea have highlighted several important patterns. However, little is known about intraspecific variation for digeneans in the marine Arctic ecosystems. Here we analyse an extended dataset of partial cox1 and nadh1 sequences for Tristriata anatis (Notocotylidae) and confirm the preliminary findings on its distribution across Eurasia. Haplotypes are not shared between Europe and the North Pacific, suggesting a lack of current connection between these populations. Periwinkle distribution and anatid migration routes are consistent with such a structure of haplotype network. The North Pacific population appears ancestral, with later expansion of T. anatis to the North Atlantic. Here the parasite circulates widely, but the direction of haplotype transfer from the north-east to the south-west is more likely than the opposite. In the eastern Barents Sea, the local transmission hotspot is favoured.

Previous studies on the life history of the nematode eel specialist Paraquimperia tenerrima (Nematoda: Quimperiidae) have failed to determine whether an intermediate host is required in the life cycle. In the laboratory, eggs failed to hatch below 10°C, hatching occurring only at temperatures between 11 and 30°C. Survival of the free-living second stage larvae (L2) was also temperature dependent, with maximal survival between 10 and 20°C. Total survival of the free-living stages (eggs and L2) is unlikely to exceed a month at normal summer water temperatures, confirming that parasite could not survive the 6 month gap between shedding of eggs in spring and infection of eels in early winter outside of a host. Eels could not be infected directly with L2, nor could a range of common freshwater invertebrate species. Third stage larvae (L3) resembling P. tenerrima were found frequently and abundantly in the swimbladder of minnows Phoxinus phoxinus from several localities throughout the year and were able to survive in this host in the laboratory for at least 6 months. Third stage larvae identical to these larvae were recovered from minnows experimentally fed L2 of P. tenerrima, and eels infected experimentally with naturally and experimentally infected minnows were found to harbour fourth stage larvae (L4) and juvenile P. tenerrima in their intestines. Finally, the whole life cycle from eggs to adult was completed in the laboratory, confirming that minnows are an obligate intermediate host for P. tenerrima.

Although the morphology of the adult stage of the majority of the helminthic parasites of domestic stock is now well known there still remains a considerable amount of work to be done on the larval stages of these worms. Some of the more recent researches on the infective stage of human and other hookworms have shown that a close study of the morphology reveals appreciable differences between the larval stages of closely allied species and that the differences can be used as diagnostic characters.

Polystoma vernoni (Polystomatidae) is a new species in the urinary bladder of Ptychadena oxyrhynchus in KwaZulu-Natal province, South Africa. Ptychadena is a true African species and the 49 currently known species in Africa harbour 11 polystome parasites. Ptychadena oxyrhynchus has an extensive distribution through Africa and harbours Polystoma prudhoei in West Africa. This new parasite differs significantly from P. prudhoei. The new species is distinguished by its long body relative to its haptor length, its unique shape and its ratio of marginal hooklets. In a sample of 13 frogs, 53.8% were infected with up to 18 parasites per host (mean intensity 4.86).