Fasciola hepatica is a trematode parasite that affects mammals, including humans. In Brazil, fascioliasis, a disease caused by the parasite, is of great importance. The disorder affects the welfare of the Brazilian population through impairing the agricultural production of cattle, where the disease causes weight loss as a result of liver damage. This study aimed to evaluate the genetic diversity of F. hepatica throughout Southern Brazil to determine its geographic origin and estimate the colonization route of the parasite. To accomplish these aims, flukes were collected from slaughterhouses in three endemic areas of Rio Grande do Sul and Paraná states. DNA was isolated using the phenol–chloroform protocol from single flukes and two mitochondrial genes, cytochrome oxidase subunit I (COI) and nicotinamide dehydrogenase subunit 1 (Nad1), were amplified and sequenced. Ten haplotypes of COI were found from 75 isolated parasites and the total haplotype and nucleotide diversity observed were 0.475 and 0.002, respectively. Using the Nad1 gene, we found 24 haplotypes from 79 samples, resulting in haplotype and nucleotide diversity values of 0.756 and 0.004, respectively. An analysis of molecular variance showed that 57.4% and 77.5% of variation was within populations (FST), while 9.0 and 36.8% of variation was among groups (FCT) when considering COI and Nad1 genes, respectively. For COI, the fixation index values of 0.425 and 0.368 were obtained for FST and FCT, respectively, while analysis of Nad1 0.225 and 0.089 index values were obtained for FST and FCT, respectively. We have determined that F. hepatica found in the two distinct areas originated from several geographical regions, since we found haplotypes that were shared with at least three different continents. These data are in accordance with the recent colonization of Brazil, and the recent import of cattle from South American, European and, possibly, some African countries. The observed FST and FCT values for COI and Nad1 genes of F. hepatica may be a result of limited movement of animals within states and support the lack of geographical structure of the parasite in Brazil, which are in agreement with the observed cattle production systems in this region.

Twenty-five species of Nematode have been found to be present in sheep in Manawatu district. The species of greatest economic importance were found to be in most cases of importance in other temperate climates.

In the cases of certain species, saturation of Manawatu district has not yet occurred, e.g., in the cases of Cooperia oncophora, C. punctata and Ostertagia ostertagi.

The countries of origin of the foundation stock have limited the number of species. Most of the importations have been made from Britain and Australia.

As few nematodes of the sheep require intermediate hosts, their entrance to a new country, New Zealand, has not been prevented to any extent on this ground. Muellerius capillaris has been able to survive on account of the abundance of its normal host, which has been introduced also.

The climate of Manawatu is such that the extremes of summer and winter are not severe enough to exert complete control on the various species. Infective stages are well able to survive these less favourable periods. The climate is sufficiently equable to enable out of door pasturing throughout the year, so that in the cases of most species of nematoda infection it is possible also throughout the year.

The farming systems in vogue involve almost solely the use of permanent pasture which is mostly of high carrying capacity. This enables concentration of stock and in conjunction with continuous grazing throughout the year, enables the excessive multiplication of the various species of nematodes.

The prominence placed on the fat lamb industry means that much attention is devoted to the raising of a population susceptible to worm infection.

A prevailing practice is to introduce culls from the surrounding hill districts for purposes of fattening, and sheep from the Hawke's Bay district in time of drought. There is consequently a continual introduction of parasites in these animals.

Cattle are the chief reservoir hosts of nematodes of sheep in Manawatu district. These occur in large numbers in the district and frequently dairying is combined with sheep farming, so that they become important sources of infection to sheep in respect to some species of worm, e.g., Cooperia oncophora, C. punctata and Ostertagia ostertagi.

It would seem that the tendency in the district is towards the increasing of the carrying capacity of pasture. This should result in the multiplication of parasites, particularly Nematodes, to a greater extent than has been the case.

The effects of Astiban, Lucanthone, Hycanthone and Niridazole on autophagic activities in the gastrodermis of Schistosoma mansoni were determined in vivo, using different dosage levels and dosage times. With Astiban, high levels of autophagy were observed in the gastrodermis 2 hours after an injection of the drug into the mouse, and this response had declined by 20 hours, marking a recovery by the parasite from the drug. Hycanthone and Lucanthone produced an autophagic response several days after the onset of treatment, and no recovery was observed in the morphology of the gastrodermis after the drug was discontinued. The effects of Niridazole on the gastrodermis were to produce the most dramatic ultrastructural changes after high doses and over several days of treatment. With all the drugs examined, gastrodermal autophagy was characterized by the formation of vacuoles containing cell components, lipid droplets and sometimes hydrolytic enzyme reaction product. The autophagic vacuoles appeared to be formed by the sequestration of cytoplasmic material by the basal membrane infoldings, and the transfer of enzymes into the vacuole from within the limiting membrane. The residues from intracellular digestion appeared to be emptied into the caecal lumen.

The morphological aspects of Schistosoma mansoni adult worms recovered from albino mice fed on a cholesterol-rich diet compared to mice fed on a standard chow were investigated. After feeding on their respective diets for over a period of 5 months, mice were subcutaneously infected with c. 50 S. mansoni cercariae/mouse. Blood samples were obtained 1 day prior to experimental infections and 63 days later, when mice were euthanized by jugular section (hypovolaemic shock). Total cholesterol (TC) levels were determined. Recovered worms were stained with hydrochloric carmine, and preserved as whole-mounts for examination by bright-field and laser confocal microscopy. The infected mice fed on high-fat chow showed higher levels of serum lipoproteins than the infected mice fed on standard chow, except for very-low-density lipoprotein cholesterol (VLDL-c) and triglycerides (TG). In this experiment, worms from mice fed on a high-fat chow showed a greater percentage of morphological differentiation regarding supernumerary testes, seminal vesicle, and seminal receptacle. In mice of this group, the rate of oocyte laying in the ovary was much higher than in control females. The present results suggest that cholesterol could be actively involved in the modulation of cell signalling and reproduction, because the lobes contained fully developed oocytes in variable amounts, different from control males. The data presented here are the first to report the role of a cholesterol-rich diet affecting the development of S. mansoni worms.

Gastrointestinal nematodes significantly affect the ovine industry, and Haemonchus contortus is considered the most pathogenic parasite in tropical regions. This situation is aggravated when the main strategy to control worms fails because of the genetic resistance that parasites acquire against anthelmintics. Aiming to anticipate the events involved in anthelmintic resistance, we induced monepantel resistance in H. contortus by in vivo subdosing of sheep hosts. Four successive passages of a monepantel-susceptible H. contortus isolate in Santa Ines or Ile de France sheep hosts resulted in three monepantel-resistant (efficacy varying from 0 to 58.5%) H. contortus isolates. Sheep hosts were treated from 0.075 mg/kg to the therapeutic dose of 2.5 mg/kg of monepantel in 19–26 rounds of selection for 112–133 weeks. Success in inducing H. contortus resistance to monepantel may have been affected by worm burden and by host–parasite interactions, including a possible effect of the breed of sheep hosts. We conclude that subdosing of sheep, although time-consuming, is an efficient in vivo strategy for the induction of monepantel resistance in H. contortus. The resistant parasites can be used in further studies to elucidate the genetic and biochemical events involved in the acquisition of anthelmintic resistance.

As a result of experimental studies conducted in the Russian southern Far East, adult worms from the genus Metagonimus were obtained. A comparative analysis of the morphometry of these worms with other Metagonimus representatives showed that they are most similar to M. katsuradai Izumi, 1935 and M. otsurui Shimazu & Urabe, 2002 found in Japan, due to the ratio of suckers and the positions of the testicle, uterus and vitellaria. However, Russian worms differ from species in Japan by other metric characters: they differ from M. otsurui by the maximum size of most organs and from M. katsuradai by body width, pharynx length, and maximum size of testes and ovary. At the same time, they are identical to a trematode from the Russian southern Far East, which was previously identified as M. katsuradai. The validity of this species was also confirmed by genetic data. According to the 28S gene and the internal transcribed spacer 2 (ITS2) region of rDNA, as well as the cytochrome c oxidase I (cox1) gene of mtDNA, the Metagonimus specimens found in Russia differ from published genetic data for other members of this genus. However, both morphological similarity and molecular data showed that M. pusillus sp. nov., M. katsuradai and M. otsurui are most likely cryptic species. Furthermore, additional data based on a mitochondrial marker were provided for M. suifunensis Shumenko, Tatonova & Besprozvannykh, 2017 from Russia.

The in vitro nematicidal effect of Chenopodium ambrosioides and Castela tortuosa n-hexane extracts (E-Cham and E-Cato, respectively) on Haemonchus contortus infective larvae (L3) and the anthelmintic effect of these extracts against the pre-adult stage of the parasite in gerbils were evaluated using both individual and combined extracts. The in vitro confrontation between larvae and extracts was performed in 24-well micro-titration plates. The results were considered 24 and 72 h post confrontation. The in vivo nematicidal effect was examined using gerbils as a study model. The extracts from the two assessed plants were obtained through maceration using n-hexane as an organic agent. Gerbils artificially infected with H. contortus L3 were treated intraperitoneally with the corresponding extract either individually or in combination. The results showed that the highest individual lethal in vitro effect (96.3%) was obtained with the E-Cham extract at 72 h post confrontation at 40 mg/ml, followed by E-Cato (78.9%) at 20 mg/ml after 72 h. The highest combined effect (98.7%) was obtained after 72 h at 40 mg/ml. The in vivo assay showed that the individual administration of the E-Cato and E-Cham extracts reduced the parasitic burden in gerbils by 27.1% and 45.8%, respectively. Furthermore, the anthelmintic efficacy increased to 57.3% when both extracts were administered in combination. The results of the present study show an important combined nematicidal effect of the two plant extracts assessed against L3 in gerbils.

Ten-day-old adults of Echinostoma caproni and E. paraensei, some of which had been exposed to 3-H-tyrosine to label sperm, were transplanted to mice in various combinations. Mating behaviour was followed on autoradiograms of worms recovered after 5 days by detecting the transfer of labelled sperm from labelled worms to themselves or to unlabelled worms. When single, labelled E. caproni adults were transplanted with unlabelled E. paraensei, they self-inseminated but did not show evidence of interspecies mating. No interspecies mating but self-insemination was observed when single, labelled E. paraensei and unlabelled E. caproni were transplanted together. When the labelled species had a choice of unlabelled adults of its own species or the opposite species, it mated in similar fashion to that seen in single species infections. The labelled species acted as if the opposite species was not present and showed an unrestricted mating pattern where it would both self- and cross-inseminate. Even though after transplant the E. paraensei adults were found in the duodenum and the E. caproni adults were found in the ileum, approximately 25% of the transplanted worms of both species were found within 1 cm of each other. Thus habitat separation was not a major cause of the lack of interspecies mating. Lack of reproductive recognition is another reason to separate E. caproni and E. paraensei into distinct species.

The worm recoveries of two different strains of Schistosoma haematobium from male hamsters and their egg-laying capacities are studied. The infection rates obtained, the growth of worms and the distribution of eggs in hamster tissues are compared with those previously described for other strains of S. haematobium.

Previous studies have shown that different geographical strains of Schistosoma haematobium have specific characteristics which reflect the infra-specific variations of this complex species (Webbe and James, 1971a, b; James and Webbe, 1973). The present paper records further observations on two strains of the parasite from the Sudan (Khartoum) and South Africa (Nelspruit).

1. In primary infections of chicks with 300 or 600 H. gallinae infective eggs, no clinical signs were apparent. Nodules were absent in all the experimental chicks as well as controls. Microscopically, few juveniles were observed in the caecal mucosa and the usual changes were mild congestion, few haemorrhages, and desquamation of superficial lining epithelial cells. Sections through a few thickened areas revealed a breached muscularis mucosa through which proliferated mucosal tissue had just invaginated into submucosa. The liver showed no changes.

2. With primary infection of chicks with 300 or 600 infective H. gallinae eggs, and their subsequent infection after 25 days with 1,000 infective eggs, there were no clinical signs after either primary or secondary infections. Nodules of varying sizes were present on the caecal wall of infected birds only, their size and number varying with age of infection. Histopathologically, the types of nodules observed were, one associated with juveniles and the other with their absence; and nodules were present both in the invaginated mucosa and in the submucosa. It was confirmed that these caecal nodules were due to irritation by H. gallinae juveniles and their metabbolites, and that these nodules were more a reaction of already sensitised caeca to subsequent infections, a fact hitherto unreported. The liver showed nothing abnormal, and there was not much difference between the haematological values of experimental and control chicks.

3. The actual process of formation of caecal nodules is demonstrated for the first time. The feasible explanation seems to be that on irritation of the already sensitised caeca by H. gallinae juveniles and their metabolites, hyperplasia of lymphoid tissue and epithelial cells results, which leads to a breach of the muscularis mucosa through which proliferated tissue of the mucosa invaginates. Later the muscularis mucosa constricts off and closes the nodule, the mucosa over it regenerates and becomes continuous. The present observations also indicate that the sterile nodular lesions usually found in natural infections may be the result of frequent infections, thus sensitising the chicks to subsequent infections.

Metazoan parasite communities of Lepomis gibbosus (Centrarchidae), one of the most successfully introduced fish species in Europe, were studied at two isolated ponds (Knielingen, Tropfen) along the Upper Rhine in Germany. Nine parasite taxa were observed, including North American species co-introduced to Europe (ancyrocephalid monogeneans, diplostomid trematodes), circumpolar species infecting L. gibbosus in both their native and non-native ranges (bothriocephalid cestodes) and locally acquired parasitic nematodes. Both parasite communities consisted predominantly of North American species. Acquisition of local parasites was not observed at Tropfen, where the fish community comprised just two species, with L. gibbosus dominant. Low prevalence and abundance of acquired parasites was found at Knielingen, which supported a diverse fish community. At Tropfen, a high abundance of the North American parasite Posthodiplostomum centrarchi probably contributed to the lower condition index, hepatomegaly and splenomegaly observed. Due to low local parasite competency, L. gibbosus appears to have no significant impact on parasite dynamics in affected habitats.

Numerous eggs of capillariid nematodes have been found in coprolites from a wide range of hosts and in raptor pellets in archaeological samples from Patagonia. The structure and sculpture of the eggshell of these nematodes and their biometry are commonly used for identification. The aim of this study was to determine whether eggs of the genus Calodium with similar morphology, found in different archaeological samples from Patagonia, belong to the same species. For this purpose, capillariid eggs (N= 843) with thick walls and radial striations were studied by permutational multivariate analysis of variance (PERMANOVA). Eggs exhibiting similar shape and structure also showed similar biometry, regardless of the zoological origin of coprolites (P= 0.84), host diet (P= 0.19), character of the archaeological sites (P= 0.67) and chronology (P= 0.66). Thus, they were attributed to the same species. We suggest that an unidentified zoonotic species of the genus Calodium occurred in the digestive tract of a wide range of hosts in Patagonia during the Holocene and that both human and animal populations were exposed to this parasite during the Holocene in the study area.

The development of molecular methods is becoming a promising field in the analysis of parasite fauna in wildlife species. This is especially useful in the case of parasite species where developmental larval stages are difficult to assess using standard methods. In this study we screened for the presence of parasitic nematodes infecting lacertid lizards from the Iberian Peninsula and Balearic islands using nematode-specific 18S ribosomal RNA gene primers on host tissue samples. Sequencing of positive samples revealed the presence of different genera of nematodes. The detection of Strongyloides, a monoxenous genus reported for the first time in Podarcis lilfordi is probably the result of the amplification of larval stages present in the host circulatory system. Two spirurid nematodes, Synhimantus and a new unidentified clade, were also found, suggesting that reptiles might be paratenic hosts of several spirurid species. This study demonstrates the benefits of using specific molecular markers on tissue samples to identify infecting larval stages of nematodes, otherwise difficult to assess using traditional screening methods.

1. The four physico-chemical characteristics of water tested— volume, salinity, pH, and turbidity—were each found to affect infection of B. glabrata by S. mansoni miracidia.

2. The rate of infection decreased as the water volume increased from 90·6% at 0·005 litre to 47·5% at 50 litres.

3. The rate of infection decreased as sodium chloride concentration increased, from 78·7% at 0·5 ppm to 2·1% at 4200 ppm. Above 4200 ppm no infection occurred. The activity of the miracidia was affected above 1200 ppm. The snails became non-motile at above 4800 ppm and died within 10 hours at higher concentrations.

A technique is described for the recovery of strongyloid infective larvae from a large number of separate small sample units of pasture. The larvae recovered from each sample unit can readily be counted individually. Tests of the technique have shown that it will recover approximately 90% of the larvae present. The efficiency of the technique is independent of the number of larvae present and of the quantity of sediment containing infective larvae which is obtained from washings of pasture samples.

Of 756 dog faecal deposits collected from the road side and public places in five Jordanian Governorates 466 (61·6%) harboured parasite ova, oocysts and/or larvae. Of these, 67·7%, 26·8%, 4·1% and 1·4% revealed one, two, three and four different types of parasite ova, oocysts or larvae in the same sample, respectively. Examination of the infected samples revealed that 44·1% contained taeniid ova, 19·8% Dipylidium caninum, 19% Toxocara canis, 8% Sarcocystis spp. oocysts, 5% hookworm larvae, 1·5% Diphyllobothrium latum, 0·1% Capillaria spp. and 0·1% Trichuris vulpis eggs.

In the spring of 1941 a male patient died at Peterborough and the autopsy which followed showed that death was due to pontine haemorrhages. As the brain also carried a coenurus, it was submitted to me for further examination. I am much indebted to Dr. David Fulton, M.D., M.R.C.S., L.R.C.P., pathologist and physician to the Peterborough and District Memorial Hospital, and to Dr. L. P. Garrod, M.R.C.S., F.R.C.P., pathologist to St. Bartholomew's Hospital, London, through whose kindness and good offices this interesting specimen was made available to me.

An infection experiment was conducted to assess the change in the proportions of Steinernema feltiae Filipjev (Site 76 strain) infective juveniles becoming male or female on exposure to the test host Galleria mellonella L. Using a mathematical model for the infection interaction, the per capita probability of penetration per unit time (transmission coefficient), for those juveniles becoming male or female, and the magnitude of the male and female classes in the infective juvenile pool were estimated. The results show that S. feltiae infective juveniles which subsequently become female have a greater probability of invasion into test hosts than their male counterparts, which leads to markedly female biased sex ratios during the initial stages of the infection interaction. As the infection progresses, however, it was found that the sex ratio became balanced. This was because the underlying sex ratio in the infective stage pool was balanced. The implications of this dynamism in the sex ratio of the entomopathogenic nematodes are discussed with respect to the infection interaction, transmission and the likely environment in which the infective juveniles reside.

Utilization of a single-species molluscan community of Lymnaea peregra by metacercariae of Echinoparyphium recurvatum over a summer (July–September) period in south-east England showed an increase in the mean number of cysts per host with host size and time of exposure. Aggregation resulting from host and habitat-related factors increased with host size and time of exposure. Encystment within the host was restricted to the peripheral organs in smaller juvenile snails but as snails increased in size, metacercariae were distributed throughout the tissues.