The location of parasites within individual hosts is often treated as a static trait, yet many parasite species can occur in multiple locations or organs within their hosts. Here, we apply distributional heat maps to study the within- and between-host infection patterns for four trematodes (Alaria marcianae, Cephalogonimus americanus, Echinostoma spp. and Ribeiroia ondatrae) within the amphibian hosts Pseudacris regilla and two species of Taricha. We developed heatmaps from 71 individual hosts from six locations in California, which illustrate stark differences among parasites both in their primary locations within amphibian hosts as well as their degree of location specificity. While metacercariae (i.e., cysts) of two parasites (C. americanus and A. marcianae) were relative generalists in habitat selection and often occurred throughout the host, two others (R. ondatrae and Echinostoma spp.) were highly localised to a specific organ or organ system. Comparing parasite distributions among these parasite taxa highlighted locations of overlap showing potential areas of interactions, such as the mandibular inner dermis region, chest and throat inner dermis and the tail reabsorption outer epidermis. Additionally, the within-host distribution of R. ondatrae differed between host species, with metacercariae aggregating in the anterior dermis areas of newts, compared with the posterior dermis area in frogs. The ability to measure fine-scale changes or alterations in parasite distributions has the potential to provide further insight about ecological questions concerning habitat preference, resource selection, host pathology and disease control.

Clinostomids are a group of digeneans in which substantial diversity has been recently discovered, with some metacercariae specific to their fish hosts. Genetic analysis has been instrumental in elucidating species diversity within this genus. Recently, seven COI lineages were reported in Argentina, along with three metacercarial morphotypes lacking molecular data. Two of these were found parasitising Rivulidae fishes. The discovery of Clinostomum metacercariae in Trigonectes aplocheiloides and Titanolebias monstrosus from temporary ponds in the western Chacoan region allowed us to redescribe the metacercariae previously identified by other authors and provide the first sequences of this lineage. The morphology of the metacercariae in both hosts matched previously reported descriptions. Genetic analysis clustered the new lineage with Clinostomum detruncatum, Clinostomum sp. 7, Clinostomum L1, and Clinostomum CRA. This discovery leaves only two morphological records of metacercariae to be characterised using DNA sequencing: one in another Rivulidae (Neofundulus paraguayensis) and one in a Loricaridae (Hypostomus sp.). The present results represent the eighth clinostomid lineage sequenced from Argentina, highlighting the extensive diversity in South America and the many lineages yet to be described or identified, considering that only one of these lineages is formally described based on adult specimens found in the heron Ardea cocoi.

Two strains of laboratory white mice, CFLP and LACA, were infected with the metacestodes of Taenia crassiceps. The serum from each infected mouse was tested for antibodies on double-diffusion gel plates and the number of antigen-antibody precipitin lines formed related (a) to the duration of the infection and (b) to the volume of metacestodes. There was a significant increase in the number of antigen-antibody precipitins with regard to the time infected but not to the volume of metacestodes. The pattern of development of the antigen-antibody precipitation system was also examined.

The redia, cercaria and metacercaria of Opisthodiscus nigrivasis from Ancylastrum fluviatilis are described. Observations were made on the behaviour of the cercaria and experimental infections with metacercariae have been carried out in laboratory-raised frogs of the species Rana ridibunda. Some features of the morphology of these juvenile stages and aspects of the behaviour of the cercaria are compared with those of others related species.

The best known biological cycles in the Diplodiscinae are those of Diplodiscus subclavatus (Pallas, 1970) Diesing, 1836, and Megalodiscus temperatus (Stafford, 1905) Hanvood, 1932. The first was described by Looss (1892), who showed that the molluscs Planorbis nitidus, Pl. vortex, Pl. rotundatus, Pl. spirorbis and Pl. contortus acted as intermediate hosts. More recently Milka (1970) found young forms of D. subclavatus in Pl. planorbis and gave a brief description of the redia and cercaria of this species.

This paper forms a preliminary account of the occurrence of some helminths parasitic in sheep and pigs in South-Eastern England. The rocks of the Wye district are mainly Cretaceous, while Romney Marsh, with its extensive sheep population, is alluvial. Earlier workers have already considered certain helminthic parasites of this region. The present writer uses Morgan's technique. Thirteen helminths parasitic in the gut of sheep and lambs are listed with notes, and a record is made of some other observations, including the identification of Ascaris lumbricoides and Œsophagostomum dentatum from swine.

The effects of crowding on growth, reproduction, rate of recovery and site of infection of Philophthalmus nocturnus were investigated by infecting various groups of day-old chicks with 25, 50,75, or 100 excysted metacercariae and examining them at 10 or 25 days post-infection. Considerable reduction in the body length and the size of the gonads was noticed in flukes grown under crowded conditions. Crowding also caused some change in the habitat of flukes, but had no effect on their rate of recovery. Very few flukes reached the ovigerous stage under overcrowded conditions and none reached the embryonated larval stage.

Schizorchis arfaai sp. n. is described from the wood-mouse in the Caspian area of Iran and its morphological characteristics compared with those of the five previously known species of Schizorchis Hansen, 1948.

An immature parafilarial worm recovered from the anterior chamber of the eye of a buffalo (Bubalus bubalis) is described. On the basis of characteristic cuticular ornamentation at the anterior extremity, an undivided short oesophagus and unequal spicules, the specimen has been identified tentatively as a male juvenile of Parafilaria bovicola. This is the first record for P. bovicola as an accidental infection of the eye of a buffalo.

The erythrokinetics of three baboons were studied over a twelve week period after infection with 3 000 cercariae of S. mansoni and compared with three uninfected control animals. In addition to monitoring changes in haematological and parasitological parameters several radioisotopic techniques were used concurrently to measure alterations in red cell kinetics. In particular 51Cr-labelled red cells and 59Fe-ferric citrate were used to measure red cell production, circulating volume, survival time and routes of loss.

All the animals remained in good condition despite heavy infection and the pathophysiological changes were in general mild and transient in nature. The principle alterations were associated with patency and consisted of a modest fall in haematocrit, some inappetence and the appearance of blood-stained mucus in the faeces. Red cell survival was reduced in the infected animals and this was correlated with an increase in faecal blood loss and haemodilution. There was no evidence of haemolytic factors or depressed erythropoiesis having any aetiological role in the anaemia.

The results confirmed the complexities of schistosomal anaemia as well as the ability of primates to withstand heavy parasitic burdens for short periods with minimal pathophysiological disturbance.

An account is given of observations on the occurrence of nematodes of the genus Meloidogyne in the Gold Coast. It includes a list of seventy-six host plants, both cultivated and wild, suitable for the sustenance and multiplication of the parasites as well as comments on the reactions of these various plant species to invasions of their root tissues. Many of the host plants listed constitute new records and the data submitted point to the conclusion that the root-knot eelworm has been long established in the Gold Coast.

Specific and non-specific esterases have been localized in sections and whole mounts of Avitellina lahorea, an intestinal parasite of sheep and goats. Non-specific esterases (NSE) were found in the sucker muscles, post-acetabular ganglia, nerve trunks, tegument, excretory canals, cirrus sac, vagina, uterus and the inner membrane of the embryophore. Acetylcholinesterase (AChE) was observed in all the above organs, including vas deferens and sperm ducts, but was absent from excretory canals and eggs. Tests with acetylthiocholine iodide (AThChI) revealed the nervous system, vas deferens, sperm ducts, uterus, cirrus sac and the vagina. The intensity of activity of AChE and AThChI was weak compared to NSE.

During the last two decades a number of species have been described in the already large genus Oxyspirura Drasche in Stossich, 1897. Twenty four new species have been described from India alone ; 2 by Singh (1948), 9 by Ali (1960), 4 by Rasheed (1960), 8 by Sultana (1964) and one by Siddiqi and M. S. Jairajpuri (1964). Recently, Oliveira Rodrigues (1962, '63) added 5 species from Brazil and Barus (1963, '65) 2 species, one from U.S.S.R. and the other from Czechoslovakia.

A survey of avian nematodes of Uttar Pradesh in India and Shagunu, Northern Nigeria yielded a number of worms from the orbital cavities of different birds. They represent 14 unidentified species of Oxyspirura and are here described as new.

All measurements are in millimetres unless otherwise stated.

The genus Galebiella Basir, 1941, has been recorded from Hydrous aculeatus Sol. (Coleoptera: Hydrophilidae) in the U.A.R. Female nematodes only were found, in the hindgut of the adult beetles.

Worms were especially abundant close to the pyloric valve and were found free in the gut lumen; a few of them were loosely attached to the gut wall.

The reaction of the hind- and midgut was almost the same yet the infection was restricted to the hindgut.

In many cases of infection the peritrophic membrane in the hindgut region became fragmented into longitudinal fibres. The intima, epithelium and muscle layers showed no changes at all.

The ingestion of soil in parks and public places containing eggs of Toxocara may constitute a significant health risk, particularly to children. To determine the most efficient method for extracting eggs from experimentally contaminated soil, two consecutive studies were undertaken. Four techniques, including washing, sieving, vacuum, and the one recommended by the World Health Organization, were evaluated. Recovery rates of over 85% were recorded with both washing and sieving methods. Using the washing technique, all combinations of the four pre-treatment solutions, distilled water, acetoacetic solution pH 5, 0.1 N sodium hydroxide and 1% Tween 20, and seven flotation fluids with different specific gravities (S.G.) ranging from 1.20 to 1.35 were assayed. The association of distilled water and saccharose solution with an S.G. of 1.27 showed the best results, with a recovery rate of 99.91%.

Seventy female lambs (6–7 months old) which were exposed to natural infections of Haemonchus contortus were designated as responders or non-responders on the basis of 10 weekly cumulative faecal egg counts. Selected responder and non-responder lambs were treated with ivermectin, housed separately and 6 weeks post-housing, seven lambs from each group were given a trickle infection of Haemonchus contortus at 1000 L3 daily for 5 days per week up to 2 weeks and examined weekly for 10 weeks after first infection. Analysis of data revealed significantly lower mean faecal egg counts and non-significantly less weight loss in responder than non-responder lambs. Mean values of haemoglobin, packed cell volume, total serum protein and peripheral eosinophil counts were significantly higher in responders than non-responders. In contrast, serum pepsinogen concentration was significantly less in responders than in non-responders. At 10 weeks post-infection, there were fewer pathological lesions and significantly lower worm burdens in responders than in non-responders. These results demonstrate a distinct resistance in responders to Haemonchus contortus infection.

A total of 140 trout were examined from four lakes in north west Ireland, Loughs Craghy, Waskel, Meela and Owennamarve. Eleven species of metazoan parasite were recorded, ten of which were of freshwater origin and Anisakissp. was the only marine species. No acanthocephalan species were found. Diphyllobothrium ditremum, D. dendriticum and Anisakissp. were the only allogenic species. Lough Owennamarve had the largest component community with nine species recorded. Lough Meela, the only brackish water lake had the smallest component community with six species recorded. Lough Waskel and Craghy had intermediate component community values. Lough Meela showed the lowest levels of similarity to any of the other lakes. Values for the Shannon-Wiener diversity index were highest for Lough Owennamarve and lowest for Lough Meela and intermediate for the other two lakes. Lough Meela had the highest values for the Simpson's dominance index and the Berger-Parker index. Lough Owennamarve had the highest Brillouin's index and Lough Meela had the lowest. The use of multiple regression techniques to control for the potentially confounding effect of geographical distance as a predictor of community similarity was discussed. No parasite species found could be considered as regionally and locally abundant and therefore described as a core species. The helminth community appears to have some degree of predictability, but chance colonization events are also important.

Acanthocephalans are a group of obligate endoparasites that alternate between vertebrates and invertebrates to complete their life cycles. Occasionally, the same individual host acts as a definitive or paratenic host for different acanthocephalan species. In this study, acanthocephalans were sampled in marine fish in three localities of the Yucatán Peninsula; adults and cystacanths were recovered from the intestine and body cavity, respectively, of Haemulon plumierii from off the coast of Sisal, Yucatán. Ribosomal DNA sequences (small and large subunits) were used to test the phylogenetic position of the species of the genus Dollfusentis, whereas the mtDNA gene cox 1 was used for assessing species delimitation. The cox 1 analysis revealed an independent genetic lineage, which is recognized herein as a new species, Dollfusentis mayae n. sp. The new species is morphologically distinguished from the other six congeners by having a cylindrical proboscis armed with 22–25 longitudinal rows bearing 12 hooks each. The cystacanths were morphologically identified as Gorgorhynchus medius by having a cylindrical trunk covered with tiny irregular spines on the anterior region, and a cylindrical proboscis armed with 17–18 longitudinal rows of 21 hooks each; small and large subunit phylogenetic analyses yielded G. medius within the family Isthomosacanthidae, suggesting that Gorgorhynchus should be transferred to this family from Rhadinorhynchidae where it is currently allocated.

Proteolytic activities in extracts from the plant-parasitic nematodes Heterodera glycines and Meloidogyneincognita were examined for their abilities to digest three FRET-modified peptide substrates representing members of the large FMRFamide-like peptide (FLP) family in nematodes. Included were sequences distributed across all nematode species (KSAYMRFa and KHEYLRFa) and a sequence confined to a narrow range of plant-parasitic nematodes (KHEFVRFa). Species variations were observed among substrate affinities, reaction rates and effect of protease inhibitors. Km values for KHEYLRFa (1.48 ± 0.34 μm) and KSAYMRFa (2.13 ± 0.24 μm) in H. glycines were each lower (P< 0.05) than those for the same substrates in M. incognita (5.26 ± 1.30 μm and 3.90 ± 0.61 μm, respectively). The Km of KHEFVRFa was lower (P< 0.05) in M. incognita (5.83 ± 0.36 μm) than in H. glycines (11.01 ± 1.26 μm). Reaction rates (Vmax/min/μg) for KHEYLRFa were the same for both species, but KSAYMRFa and KHEFVRFa digestion rates were each nearly twofold higher (P< 0.05) in M. incognita than in H. glycines. Digestion of KSAYMRFa was strongly inhibited in both species by 4-(2-aminoethyl)-benzenesulfonyl-fluoride-HCl (AEBSF) and EDTA, but M. incognita was more sensitive (P< 0.05) to inhibition. AEBSF and EDTA (both at 1 mm) inhibited M. incognita activity 62.3% and 36.6% more, respectively, than H. glycines activity. Serine protease inhibition differed significantly (P< 0.05) between the two species. Maximum inhibition of M. incognita (76%) occurred at 1.85 mm AEBSF while maximum inhibition of H. glycines was 40% at 1.19 mm AEBSF.