Cercaria londonensis Khan, 1900 is shown to develop into a new species of Echinosloma. The stages in the life history are described.

Dictyocaulus viviparus were harvested from calves treated daily with albendazole at dose-rates sub-lethal to this parasite and from matched untreated calves. Male and female reproductive tracts from the worms were examined by light and transmission electron microscopy. A first description of the testis of this nematode is provided. Cell division in the germinal zone of both male and female worms was arrested by in vivo exposure to albendazole metabolites and the cytoplasmic threads connecting the germinal cells to the rachis disappeared. In male worms from treated calves, the rachis was absent from the growth zone and severe ultrastructural damage of spermatogonia, spermatocytes and spermatozoa was apparent. In female worms, the rachis remained intact in the growth zone, obvious abnormalities being confined to the germinal zone, where the cytoplasm of the oogonia was disrupted and few nuclei seen, and to the uteri and ovijector which contained only undifferentiated ova. The detrimental effects of albendazole metabolites on male and female worms were quickly reversed after withdrawal of medication.

Migration and development of the larvae of Gnathostoma nipponicum in the rat as second intermediate or paratenic host and the weasel as definitive host were examined to clarify the pathogenesis in each animal. The advanced third-stage larvae (AdL3) given orally to rats remained in the stomach for 12 h post-infection (PI). After that, larvae transiently invaded various organs and finally moved into the muscle within 48 h. The percentage of eosinophils in the blood taken from the jugular vein of rats infected with AdL3 reached a maximum (about 6%) on day 20 PI and then decreased. IgG antibody titre for G. nipponicum measured by ELISA began to increase on day 5 PI and reached a plateau on day 20 PI. The AdL3 given orally to weasels moved from the stomach into the muscle and then increased in size. Half of them invaded the muscle within 5 days, whereas the majority of them invaded the muscles within 20 days PI. Morphology of worms which invaded the muscles indicated that they were still the larval form with three rows of hooklets on the head bulb. The larvae in the muscles developed to young adult worms with seven rows of hooklets on the head bulb within 40 days PI. These young adult worms invaded the oesophageal wall and formed a tumour within 60 days PI. It was presumed that worms invaded the oesophageal wall though the adventitia. Ferret and mink were shown to be potential final hosts of G. nipponicum.

Following the oral administration of third- and fourth-stage A. suum larvae, which had previously completed nine or ten days somatic migration in guineapigs, rabbits or a pig, six out of eight pigs showed a rise of serum antibody titre, as measured by the conglutinating complement absorption test using a saline extract of Ascaris worm as antigen. Four of these pigs had negative titres before infection, and in these animals antibodies were first detected between the 14th and 20th days. Maximum serum antibody concentration was reached between the 14th and 34th days of infection, and antibodies were detected for at least as long as 68 days.

Larvae were recovered from the faeces on the 23rd and 29th days of infection, and in two pigs out of eight the larvae reached maturity, eggs first being seen in the faeces on the 42nd day.

The results suggest that (1) Ascaris larvae, on their return to the intestine, release antigenic substances which are then absorbed by the gut wall to stimulate the production of antibodies; (2) the secondary antibody rise, which occurs about the sixth or seventh week of an infection with Ascaris eggs, is due to the absorption of this larval antigen; and (3) the moulting process (fourth moult) is not only an important stage for stimulating this further antibody production, but is also the time when maturing larvae are affected by the immune mechanisms of the host.

On reinfection with Ascaris eggs the phenomenon of “self-cure” was noticed. A fall in the faecal egg count, which became negative on the 21st day, was accompanied by a sharp rise in antibody titre. An increase in the number of infertile eggs in the faeces, rising from 11% on the day of reinfection to 100% on the 14th day, was also observed.

Velacumantus australis is a common mollusc along the easter and southern coast of Australia. A study of the incidence of larval trematodes in several populations of V. australis showed that the incidence of the various infections varied considerably with time and place. Heterophyids were usually the commonest infection, while schistosomes and echinostomes were frequently absent. In one population, seasonal changes in the incidence of philophthalmids and schistosomes were found to be positively correlated, and seasonal changes in the incidence of philophthalmids and echinostomes were found to be negatively correlated. These results are discussed.

Of over 250 species of Monorchiidae Odhner, 1911, just four are known from gerreid fishes. Here, we report adult specimens of a new species infecting Gerres oyena (Forsskål) and Gerres subfasciatus Cuvier from off Heron Island and North Stradbroke Island, Queensland, Australia. The species is morphologically most similar to the concept of Lasiotocus Looss, 1907, which currently comprises eight species, in the possession of an unspined genital atrium, bipartite terminal organ, round oral sucker and unlobed ovary. However, phylogenetic analyses of the 28S ribosomal DNA gene region shows the species to be distantly related to the two sequenced species of Lasiotocus – Lasiotocus mulli (Stossich, 1883) Odhner, 1911 and Lasiotocus trachinoti Overstreet & Brown, 1970 – and that it clearly requires a distinct genus; thus, we propose Gerricola queenslandensis n. g., n. sp. Morphologically, G. queenslandensis n. g., n. sp. differs significantly from L. mulli and L. trachinoti only in the possession of distinctly longer caeca, which terminate in the post-testicular region, and in the absence of a distinct gap in the terminal organ spines. The remaining species of Lasiotocus possess caeca that also terminate in the post-testicular region, which might warrant their transfer to Gerricola n. g. However, doubt about their monophyly due to a combination of significant morphological variation, a lack of information on some features and infection of a wide range of hosts, lead us to retain these taxa as species of Lasiotocus until molecular sequence data are available to better inform their phylogenetic and taxonomic positions. Sporocysts and cercariae of G. queenslandensis n. g., n. sp. were found in a lucinid bivalve, Codakia paytenorum (Iredale), from Heron Island. Sexual adult and intramolluscan stages were genetically matched with the ITS2 ribosomal DNA and cox1 mitochondrial DNA regions. This is the second record of the Lucinidae as a first intermediate host for the Monorchiidae. Additionally, we report sporocysts and cercariae of another monorchiid infection in a tellinid bivalve, Jactellina clathrata (Deshayes), from Heron Island. Molecular sequence data for this species do not match any sequenced species and phylogenetic analyses do not suggest any generic position.

Little is known about the efficacy of cysteine proteinases (CP) as anthelmintics for cestode infections in vivo. Hymenolepis microstoma is a natural parasite of house mice, and provides a convenient model system for the assessment of novel drugs for anthelmintic activity against cestodes. The experiments described in this paper indicate that treatment of H. microstoma infections in mice with the supernatant of papaya latex (PLS), containing active cysteine proteinases, is only minimally efficacious. The statistically significant effects seen on worm burden and biomass showed little evidence of dose dependency, were temporary and the role of cysteine proteinases as the active principles in PLS was not confirmed by specific inhibition with E-64. Worm fecundity was not affected by treatment at the doses used. We conclude also that this in vivo host–parasite system is not sensitive enough to be used reliably for the detection of cestocidal activity of compounds being screened as potential, novel anthelmintics.

The distribution of parasites within host populations and communities, and the mechanisms responsible for these patterns, are poorly understood aspects of wildlife parasitology. Here, we evaluate the influence of the average abundance of endoparasite variance, using endoparasites of lizards from the Caatinga domain (semiarid region), north-eastern Brazil. We hypothesized that, due to the high number of generalist endoparasite species, they may occur randomly throughout host populations in an aggregate pattern. In addition, we evaluated the degree to which sample variance is influenced by the average abundance of endoparasite species, patterns of co-occurrence and dominance among endoparasite species and similarities between abundance and the richness of endoparasite infracommunities in several host species. Between September 2015 and February 2016, 2141 lizards (1233 infected) from 16 species were collected from six Caatinga areas. In total, 25,687 endoparasites were collected, which belonged to 13 species including nematodes, pentastomids, cestodes, trematodes and acanthocephalans. Parasite–host associations documented here included 39 newly identified interactions. Endoparasites occurred in a typical aggregate pattern of distribution within their hosts; there was no measurable preference related to the acquisition of hosts by endoparasites. Despite the new records, endoparasites found were commonly associated with lizards in Caatinga environments, which may reflect fauna composed of generalist endoparasite species.

Environmental changes and ecological disturbances can have large and unpredictable effects on parasite dynamics. Increasing human impacts on freshwater ecosystems through land use may thus modify the distribution and abundance of parasites and have cascading effects on host populations. Here we tested the effects of small-scale riparian forest management on the nematode Cystidicoloides ephemeridarum and its insect intermediate host Ephemera danica in forested streams. We assessed the impacts of harvesting riparian trees on parasite prevalence and abundance concomitantly with host densities. We also looked at upstream and downstream reaches to document potential cascading effects on unaltered stream sections mediated by aerial dispersal of adult mayfly or downstream drift of E. danica larvae. We show that host densities and parasite levels (prevalence and abundance) increased significantly following riparian tree removal. Overall, parasite densities showed a 6- to 66-fold increase in harvested reaches compared to upstream, pristine reaches. Similar effects were also clear downstream of the disturbance. Thus, despite the small extent of riparian forest alteration along the study streams, both parasite and intermediate host were strongly affected. Small-scale riparian forest management may thus have large, unforeseen impacts on some aspects of freshwater ecosystem structure and functioning that are often ignored. Generally, understanding how human perturbations influence parasites is vital when trying to predict overall impacts on ecosystem structure and functioning, and how changes in infection dynamics may further affect host species.

About the middle of July, 1932, red galls were discovered on blades of grass in a meadow at Winches Farm, St. Albans, by Mr. W. A. Macdonald, who drew the attention of the writer to the presence of nematodes within them. Subsequent search on this and an adjoining meadow proved that the galls were widely distributed, on the same kind of grass, over the whole area, whilst some days later similar galls were found on a bank by the side of the main road from St. Albans to Hatfield. The grass was identified as Agrostis tenuis Sibth. (Agrostis vulgaris With.), popularly called Fine Bent-grass.

The scanning and infective capacity of Schistosoma mansoni and S. haematobium miracidia were tested under limited exposure times in small volumes of water, and under increasing mutual dispersion in vessels of different sizes also over increasing horizontal distances, and under different flow rates of water. It was found that the miracidia of both species retained their infective capacity for up to 1 hour in the presence of susceptible snails. The infection rates decreased with decreasing miracidial densities but was still over 50% at 0.4–0.8 miracidia per litre. Both species of miracidia produced high (36–44%) infection rates in host snails situated at a distance of 5 m and equally high infection rates (39–40%) in snails placed in water flowing at a rate of 12–15 cm/sec.

The application of any of these physical factors in the control of schistosomiasis is discussed.

Rodents, particularly those belonging to the family Muridae, form the largest group of mammals in Malaysia. They are also a group that has been well studied because of their medical and economic importance. Yet, comparatively little is known, in Malaysia, about the helminths that are associated with them; far less the types of terrain in which these are prevalent. An attempt is now made to survey the nematodes parasitic in these rodents, with a view to assessing the potential risk from those that are harmful to man and domestic animals, and to studying those that are harmless, but nevertheless form an enlightening contribution to the knowledge of Malaysian parasitic fauna.

Natural infections of three freshwater snails with Fasciola hepatica and/or Paramphistomum daubneyi were studied during two periods in 1996 and 1997 (June–July and September–October) on 18 farms located in the departments of Vienne and Haute Vienne (central France), and known for low prevalences of F. hepatica infections in ruminants. A total of 1573 Lymnaea glabra and 1421 L. truncatula 6 mm high or more were collected in the meadows of 13 farms and dissected under laboratory conditions. Snails with single or concurrent infections of F. hepatica and/or P. daubneyi were found for each Lymnaea species. InL. truncatula, global prevalences of natural infections with F. hepatica (3.8% in June–July, and 3.6% in September–October) were significantly greater than those recorded for P. daubneyi (1.1% and 0.8%, respectively). In L. glabra, global prevalences of F. hepatica infections (0.4% in each investigation period) were significantly lower than those found in L. truncatula, whereas there were no significant differences between prevalences of P. daubneyi infections. A total of 2721 Planorbis leucostoma measuring at least 4 mm in diameter were collected in the meadows of the other five farms on which L. truncatula was absent. In these planorbids, global prevalences of natural infections with F. hepatica were 0.4% in each period of investigation. Contrary to fasciolosis, snail infections with P. daubneyi were not noted on all farms of the Vienne and Haute-Vienne departments. Natural single or concurrent infections with F. hepatica and/or P. daubneyi in L. glabra and a natural infection of P. leucostoma with F. hepatica were found in swampy meadows on acid soil.

The widespread distribution in Britain of the grey squirrel prompted an investigation of the parasite fauna of this rodent to find if it was capable of acting as a disseminator of parasites to other mammals or birds, particularly domesticated ones.

In 1978, the theory behind helminth parasites having the potential to regulate the abundance of their host populations was formalized based on the understanding that those helminth macroparasites that reduce survival or fecundity of the infected host population would be among the forces limiting unregulated host population growth. Now, 45 years later, a phenomenal breadth of factors that directly or indirectly affect the host–helminth interaction has emerged. Based largely on publications from the past 5 years, this review explores the host–helminth interaction from three lenses: the perspective of the helminth, the host, and the environment. What biotic and abiotic as well as social and intrinsic host factors affect helminths? What are the negative, and positive, implications for host populations and communities? What are the larger-scale implications of the host–helminth dynamic on the environment, and what evidence do we have that human-induced environmental change will modify this dynamic? The overwhelming message is that context is everything. Our understanding of second-, third-, and fourth-level interactions is extremely limited, and we are far from drawing generalizations about the myriad of microbe-helminth-host interactions.Yet the intricate, co-evolved balance and complexity of these interactions may provide a level of resilience in the face of global environmental change. Hopefully, this albeit limited compilation of recent research will spark new interdisciplinary studies, and application of the One Health approach to all helminth systems will generate new and testable conceptual frameworks that encompass our understanding of the host–helminth–environment triad.

Wild Lymnaea tomentosa snails, recovered from Lake Wanaka, New Zealand, were established in the laboratory. Wild snails, naturally infected with echinostomes, provided metacercariae for infection of laboratory maintained snails. Metacercarial cysts from wild and laboratory snails were then used to attempt infection of definitive host candidates. Laboratory snails provided convenient packaging of known numbers of cysts. Metacercariae excysted in the small intestines of ducklings to mature in 6 days. Worms were expelled as they became gravid. Attempts to establish infections in experimental hosts other than ducklings were not successful. No worms were recovered from mice, white rats, guinea pigs, hamsters or immunosuppressed white rats.

A total of 444 adult frogs (Rana temporaria) were obtained from three sites in the east of Ireland. Oswaldocruzia filiformis was present at all times of the year; overall, 64% of the frogs were infected, with a mean burden of 5 worms/frog. Most of the parasites were in the first half of the small intestine. A single gross lesion associated with a high worm burden is described. Female parasites were more abundant than males. Most parasitic stages of O. filiformis overwintered in hibernating hosts. Seasonal patterns in the levels of parasitization were not discerned. The intensity of infection was significantly greater in female than male frogs at one of the sites. There was little correlation between the size of host and degree of parasitization. None of the 45 frog tadpoles examined harboured O. filiformis. Frogs became infected by August of their first year.

In a previous paper the writer (1929) has given an account of the initiation and earlier work on a field plot experiment at Winches Farm devoted to the study of the stem eelworm, Anguillulina dipsaci, in its attacks on potato tubers. For the trials carried out in 1928 the original plot, which was 200 ft. long by about 21 ft. 9 ins. wide, was divided up into 30 smaller plots, each measuring 12 ft. long by 10 ft. 9 ins. wide, and 10 varieties of potatoes were tested, each variety being grown in triplicate. Following an inoculation of the soil with diseased tubers, it was found that all the varieties grown, whether earlies, second-earlies or main-crops, became infected. Since 1928 the plot has been cropped each year with potatoes and the purpose of the present paper is to put on record observations made and results obtained in subsequent years and to advance certain conclusions arrived at as a result of this work.

Ælurostrongylus abstrusus, discovered by Mueller in the lungs of cats in Germany, has since been reported from various other countries in Europe. In many cases the diagnosis has been based on the recovery of the characteristic larva but occasionally a few adults have been found. These have generally been isolated by teasing up the lung substance in normal saline and then searching through the fluid by means of a low-powered objective or a dissecting microscope. The technique adopted by the writer was to cut thin slices of lung tissue, to compress these between two ordinary glass slides, and to examine them with an inch objective. The larvæ could be easily found in the expressed fluid and adults could be noticed as dark masses in the lung itself. When seen, the adults were removed by means of dissecting needles.

Histological and histochemical studies were made on the excysted metacercariae and cercariae of Echinostoma revolutum and E. trivolvis. The paraoesophageal glands of the cercariae of both echinostome species stained positively with the intravital dyes, neutral red and nile blue sulphate. The paraoesophageal glands of excysted metacercariae of E. revolutum did not display positive staining with the intravital dyes. Some excysted metacercariae of E. trivolvis displayed positive staining of the paraoesophageal glands, while others displayed either a negative reaction or reduced staining. The lack of staining with intravital dyes, of paraoesophageal glands of excysted metacercariae of E. revolutum, suggests that the glands play a role in either the final stages of encystment, or in excystation in E. revolutum.