Different courses of microsporidiosis, related to the route of infection, were observed in severe combined immunodeficient (SCID) mice inoculated with spores of the human microsporidian Trachipleistophora hominis (Phylum Microspora). After eye contamination by spores the mice became moribund within 7 to 8 weeks, showing severe infection in the conjunctiva and cornea, and lighter infections in the urinary bladder, liver and spleen. The mean survival time of intramuscularly inoculated SCID mice was 12 weeks, when heavy infection was found in muscles around the site of inoculation, and also in several viscera. Subcutaneously inoculated SCID mice developed skin lesions around the inoculation sites, and heavy urinary bladder infection, and died 6 or 7 weeks after inoculation. Intracerebrally inoculated SCID mice became moribund 5 or 6 weeks after inoculation with massive infection in the urinary bladder and liver, but none in the brain. Intraperitoneally inoculated SCID mice survived for 13 weeks and the urinary bladder and liver were the most heavily infected organs. The SCID mice, inoculated perorally and examined after 23 weeks, were uninfected. Infection was not detected in the brain of any of the inoculated SCID mice. Our results show that T. hominis has very little tissue specificity. Peroral infection seems to be ineffective in T. hominis, but eye contamination or insect bite (as mimicked by injection) are suggested as possible routes of infection under natural conditions.

The objective of this study was to identify species of Angiostrongylus spp. infecting wild carnivores in Southern Brazil, as well as to describe gross and histopathological findings associated with the infection. Necropsy was conducted in 16 wild carnivores parasitized by Angiostrongylus spp. Analysed lungs revealed multifocal dark-red areas of consolidation; in one case, multifocal firm white nodules spread in all pulmonary lobes were observed. In one animal, a focally extensive area of malacia associated with haemorrhage was noted in the encephalon. Histologically, multifocal granulomatous pneumonia or bronchopneumonia, associated with eggs and larvae in blood vessels, lung interstitium, alveoli, and sometimes in bronchi and bronchioles was observed. Adult nematodes were seen within blood vessels. The lesion observed in the brain was characterized as a focally extensive area of malacia associated with gitter cells, haemorrhage, thrombosis and a free intralesional larva. Through molecular techniques, seven positive samples of Angiostrongylus cantonensis were obtained, including the brain sample, and a positive sample of Angiostrongylus vasorum-like, all in Cerdocyon thous. The positive sample for A. vasorum showed 97% similarity with sequences deposited in GenBank, suggesting a new species or subspecies of Angiostrongylus sp. Infection of Lycalopex gymnocercus by Angiostrongylus spp. was confirmed by histological evaluation.

Inter-simple sequence repeats markers were used to determinate the genetic variability of Fasciola hepatica populations recovered from sheep and cattle from Spain (Sp1, Sp2, Sp3 and Sp4), UK (Eng), Ireland (Ir) and Mexico (Mex). Twenty five primers were tested but only five produced 39 reproducible bands, being 71·79% polymorphic bands. This percentage ranged from 10·26% in Sp4 to 48·72% in Sp1, and per host between 28·21 and 48·72% in sheep and between 10·26 and 38·46% in cattle. This relatively low range of genetic diversity within populations, with a mean of 34·40%, implies that a large proportion of variation resided among populations. The population differentiation (Gst = 0·547) indicated that 54·7% of variation is due to differences between populations and 45·3% due to differences within population. The Nei's distance ranged between 0·091 and 0·230 in sheep and between 0·150 and 0·337 in cattle. The genetic relationships between populations and individuals were shown by a UPGMA dendrogram and a principal coordinate analysis; both grouped all populations separately from Sp4, a population of from the Midwest of Spain with the lowest level of diversity. Small genetic distances were observed between Eng and Ir, on the one hand, and Sp1, Sp2, Sp3, from the Northwest of Spain, together with Mex, on the other.

Species of Protopolystoma are monogenean flukes that only infect allopolyploid hosts in the anuran genus Xenopus. Multivariate analyses of morphometric sclerite characters in the nominal species Protopolystoma simplicis suggest that morphologically distinguishable populations occur in the tetraploid host, Xenopus laevis victorianus, and in each of the octoploid hosts, X. vestitus and X. wittei. The species-level divergence of a lineage specific to X. laevis is supported by sequence variation in the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Protopolystoma simplicis from X. laevis is redesignated P. microsclera n. sp., with P. simplicis being retained for populations in octoploid hosts. This division is consistent with large differences in egg hatching schedule, fixed differences at the mannose-6-phosphate isomerase and fumarate hydratase loci, and host-specificity in experimental analyses. Although the respective P. simplicis populations in X. vestitus and X. wittei also show significant diversity in allozyme expression, morphometrics and egg hatching schedule, they are retained in the same species because their level of mitochondrial DNA divergence is similar to that found within other Protopolystoma species. The consequences of splitting P. simplicis for a recent interpretation of the origin of Protopolystoma faunas in octoploid Xenopus spp. is discussed.

Ovine babesiosis is one of the most important tick-borne haemoparasitic diseases of small ruminants. The ovine parasite Babesia sp. Xinjiang is widespread in China. In this study, recombinant full-length XJrRAP-1aα2 (rhoptry-associated protein 1aα2) and C-terminal XJrRAP-1aα2 CT of Babesia sp. Xinjiang were expressed and used to evaluate their diagnostic potential for Babesia sp. Xinjiang infections by indirect enzyme-linked immunosorbent assay (ELISA). Purified XJrRAP-1aα2 was tested for reactivity with sera from animals experimentally infected with Babesia sp. Xinjiang and other haemoparasites using Western blotting and ELISA. The results showed no cross-reactivities between XJrRAP-1aα2 CT and sera from animals infected by other pathogens. High level of antibodies against RAP-1a usually lasted 10 weeks post-infection (wpi). A total of 3690 serum samples from small ruminants in 23 provinces located in 59 different regions of China were tested by ELISA. The results indicated that the average positive rate was 30·43%, and the infections were found in all of the investigated provinces. This is the first report on the expression and potential use of a recombinant XJrRAP-1aα2 CT antigen for the development of serological assays for the diagnosis of ovine babesiosis, caused by Babesia sp. Xinjiang.

1. The area (Fig. 1) may be divided into a forested uninhabited mountain region, a region of low hillocks with between them marshy bottoms, many of which had been cleared and cultivated, and a flat coastal plain protected from the sea by a wall which leaked. Rain fell from early June till late September, and the rest of the year was mainly rainless.

2. Little is known about the mountain region. A. minimus was found infected in April, at which time, however, most potential breeding-places were dry. Larvae of A. maculatus were abundant, but the adults did not bite man.

3. Malaria was intense locally in the hillocks and coastal plain region, but uneven in distribution (Fig. 1). Evidence of active transmission in March and April, during the rains, and in October was found, there was a lull in May and June, but any other lulls there may have been were not discovered, since observations through the year were not possible.

4. Observations at night revealed A. leucosphyrus, A. jeyporiensis and A. minimus near man and rarely near cattle. A. sundaicus, A. philippinensis, A. annularis and A. hyrcanus attacked both man and cattle, though some, at least, would attack man only in the absence of cattle. A. aconitus was found near man at night, but nearly all the specimens contained old blood.

5. A. subpictus and A. vagus fed on cattle and entered houses at dawn in search of shelter for the day. The man-biters mainly sought shelter in some outdoor resting-place. The conclusion was that the standard practice of searching for mosquitoes in houses early in the morning gave results which were not only valueless, but misleading (Fig. 2).

6. Few dissections were made and sporozoites were found only in A. jeyporiensis (2/126= 1·6%), which was thought to be responsible for most of the malaria transmitted early in the year. It is suggested that the results of night catching provide valuable circumstantial evidence about vectors.

7. The night catches also gave information about time of biting, and yielded two observations of importance in control work. A. minimus, A. jeyporiensis, A. philippinensis and A. sundaicus did not attack until several hours after nightfall. A. philippinensis, in late May, when it was not raining, preferred to bite persons sleeping out of doors. Elsewhere it was observed that A. philippinensis did this and also did not rest nearby before or after feeding as other species did. It might, therefore, avoid a contact insecticide. A. sundaicus, baulked of a feed by night, attacked after sunrise.

In some notes on the Trematodes of Northumbria published in 1905 a few remarks were made on a larval Trematode inhabiting the liver of the common periwinkle Littorina littorea. The liver in two per cent. of the periwinkles from Budle Bay was full of rediæ containing cercariæ more or less developed, the latter agreeing in every way with an encysted Echinostomum larva which inhabits mussels, cockles and other bivalve mollusks in the same locality. So close was the resemblance that I had no hesitation in declaring them to be the same worm in different stages, but hoped for an opportunity of demonstrating this by experiment. In October 1908 through the courtesy of Professor Meek I had the opportunity of conducting some feeding experiments in the Dove Marine Laboratory, Cullercoats, which have given satisfactory results, and although it is not possible to state absolutely that the forms are identical yet the evidence is so strong that I think I am justified in regarding the young worm in the periwinkle as an earlier larval form of the encysted worm in the foot of the mussel and cockle.

The ‘crowding effect’ is a result of competition by parasites within a host for finite resources. Typically, the severity of this effect increases with increasing numbers of parasites within a host and manifests in reduced body size and thus fitness. Evidence for the crowding effect is mixed – while some have found negative effects, others have found a positive effect of increased parasite load on parasite fitness. Parasites are consumers with diverse trophic strategies reflected in their life history traits. These distinctions are useful to predict the effects of crowding. We studied a parasitic castrator, a parasite that usurps host reproductive energy and renders the host sterile. Parasitic castrators typically occur as single infections within hosts. With multiple parasitic castrators, we expect strong competition and evidence of crowding. We directly assess the effect of crowding on reproductive success in a barnacle population infected by a unique parasitic castrator, Hemioniscus balani, an isopod parasite that infects and blocks reproduction of barnacles. We find (1) strong evidence of crowding in double infections, (2) increased frequency of double infections in larger barnacle hosts with more resources and (3) perfect compensation in egg production, supporting strong space limitation. Our results document that the effects of crowding are particularly severe for this parasitic castrator, and may be applicable to other castrators that are also resource or space limited.

Digenean parasites infecting four Cominella whelk species (C. glandiformis, C. adspersa, C. maculosa and C. virgata), which inhabit New Zealand's intertidal zone, were analysed using molecular techniques. Mitochondrial 16S and cytochrome oxidase 1 (COI) and nuclear rDNA ITS1 sequences were used to infer phylogenetic relationships amongst digenea. Host species were parasitized by a diverse range of digenea (Platyhelminthes, Trematoda), representing seven families: Echinostomatidae, Opecoelidae, Microphallidae, Strigeidae and three, as yet, undetermined families A, B and C. Each parasite family infected between one and three host whelk species, and infection levels were typically low (average infection rates ranged from 1·4 to 3·6%). Host specificity ranged from highly species-specific amongst the echinostomes, which were only ever observed infecting C. glandiformis, to the more generalist opecoelids and strigeids, which were capable of infecting three out of four of the Cominella species analysed. Digeneans displayed a highly variable geographic range; for example, echinostomes had a large geographic range stretching the length of New Zealand, from Northland to Otago, whereas Family B parasites were restricted to fairly small areas of the North Island. Our results add to a growing body of research identifying wide ranges in both host specificity and geographic range amongst intertidal, multi-host parasite systems.

A report is made of nine cases in which Diploscapter coronata was found, in great abundance and in all stages of development, in human stomachs containing little or no hydrochloric acid. A critical review is given of the literature of parasitism of vertebrates by rhabditid worms, and it is concluded that these worms may establish themselves and multiply in diseased female urino-genital systems as well as in hypohydrochloric stomachs, and may live as larvae in the skin, particularly when this is mangy, or multiply on the surface of the skin, but that the evidence of establishment in the intestine or respiratory system of mammals is still inadequate.

Peritoneal macrophages from Mesocestoides corti-infected mice showed a marked and progressive loss of ability to act as accessory cells for syngeneic Con A-stimulated mesenteric lymph node lymphocytes. The same effect on the macrophages could be induced by intraperitoneal injection of M. corti culture supernatant, despite a concurrent increase in numbers of peritoneal adhesive macrophages. The findings are used to compare and contrast the known immunomodulatory effects of M. corti and taeniid metacestodes, the latter differing chiefly in their potential for modifying T-cell as well as macrophage behaviour.

Male rats were more susceptible than female rats to experimental infection with Amplicaecum robertsi. This sex difference first appeared at the time of puberty, i.e. about 50 days of age.

Suckling rats were less susceptible to infection than weanlings. This was attributed to the cumulative effects of intestinal structure, the indirect effects of milk on the physio-chemical factors in the gut, and the direct effects of milk on the worms themselves.

The rat showed an age resistance to A. robertsi: this was greatest in the female host.

The larvae recovered from females were shorter than those recovered from male rats except in immature animals.

The longest larvae were recovered from suckling rats: in old rats the length of the larvae recovered became progressively shorter as the animals aged.

This investigation was carried out during the tenure of a Senior Research Fellowship from the Wool Research Council of Australia. I should like to thank Professor J. F. A. Sprent for his help and Mr C. Wilkinson for his technical assistance.

Clones of Trypanosoma congolense which express resistance to the widely used trypanocide isometamidium chloride accumulate less of the drug than clones which are sensitive to drug treatment. A mathematical model has been developed which was able to predict theoretical lines representing the uptake kinetics in trypanosomes which were sensitive to isometamidium, as well as for resistant trypanosomes in which reduced accumulation was a result of either reduced uptake or enhanced efflux of the drug. Data from drug uptake experiments were then fitted to these theoretical lines. While the value for drug efflux could not be separated from the dissociation constant of the trypanosomes for isometamidium, it was demonstrated that reduced accumulation is not a result of reduced uptake of isometamidium by drug-resistant trypanosomes.

Coccidian oocysts from feces of 46 individuals of the garden dormouse, Eliomys quercinus (Rodentia: Gliridae), were morphologically and molecularly characterized. Both morphological and sequence data (18S rDNA and ORF 470) showed low variability, indicating that all samples represent a single species. By comparison with published morphological descriptions of coccidia from glirid rodents, we determined that the samples represent Eimeria myoxi. Molecular data suggest that this species does not fall within the 2 known rodent-specific groups but branches as a third independent lineage. However, its exact position in respect to other eimerian clusters could not be established due to the lack of phylogenetic information at this taxonomic level for the 18S rRNA and ORF 470 genes. Based on these results, we provide a re-description of Eimeria myoxi, which contains morphological and molecular characteristics sufficient for its further unequivocal identification.

Hybridoma clones producing IgM naturally occurring (natural) antibodies were generated from naive Balb/c mice and characterized for reactivity against parasite antigens. Ascites of mice injected with these hybridomas reacted with Toxoplasma gondii soluble antigen at levels approximately 1000–10000 times higher than serum pooled from mice used for generating hybridomas as determined by a conventional enzyme-linked immunosorbent assay. Western blot analysis indicated that these monoclonal antibodies reacted with multiple antigen molecules of T. gondii with patterns similar to that of pooled mouse sera. These antibodies also reacted with multiple antigens of Plasmodium yoelii, Entamoeba histolytica, Ascaris lumbricoides, Toxocara canis, Trichuris vulpis, Fasciola hepatica, Schistosoma mansoni, and Dipylidium caninum. When one monoclonal antibody was absorbed with these parasite antigens, its reactivity with T. gondii antigen molecules was consistently reduced, independent of parasite species. These natural antibodies failed to kill T. gondii tachyzoites in vitro or to protect mice from lethal challenge with T. gondii. These results indicate that natural antibodies detected in sera of naive mice are secreted from certain B cell populations and that these antibodies are multireactive with parasite antigens and have low affinity.

Cattle production in extensive systems favours the occurrence of gastrointestinal nematodes, and the use of nematophagous fungi complements the control strategies for these nematodes. The aim of this study was to evaluate the effectiveness of the fungi Arthrobotrys cladodes and Pochonia chlamydosporia in the biological control of gastrointestinal parasitic nematodes in grazing cattle. Twenty-four calves were randomly divided into four groups and allocated to independent paddocks from February 2018 to January 2019. In the first group, the animals received pellets containing P. chlamydosporia. In the second group, the animals received pellets containing A. cladodes. In the third group, the animals received pellets containing a combination of the fungi A. cladodes and P. chlamydosporia. In the control group, the animals received pellets without fungus. The combined use of A. cladodes and P. chlamydosporia showed greater efficacy in the biological control of bovine gastrointestinal parasitic nematodes than the same fungi used separately. The parasite load was lower and weight gain was greater (P ⩽ 0.05) in the groups of cattle treated with nematophagous fungi. Therefore, the use of A. cladodes and P. chlamydosporia is promising in the biological control of nematodiosis in cattle.

This study examines the ultrastructure of the posterior vacuole in frozen-etched spores of Thelohania bracteata (Nosematidae), a microsporidian infecting the fat body of larval black-flies (Simuliidae). This organelle, considered important in providing intrasporal pressure for sporoplasm extrusion through the polar filament, has a double membrane with particles on its internal faces as revealed by the freeze-etching technique. The size and pattern of these particles differ from those in membranes of the polar filament and nucleus, and this difference may have functional significance. The posterior vacuole, and also the polaroplast, may originate from expanded sacs that occur in the immature spore. There is evidence from this study that there are many basic ultrastructural similarities between spores of different microsporidian species and that at least some reported differences are the result of varying techniques.

We gratefully acknowledge the freeze-etching facilities provided by the Department of Pathology, Faculty of Medicine, McMaster University. The research was supported by Grant A-130 from the National Research Council of Canada.

Christian Gottfried Ehrenberg, one of the outstanding scientific figures of last century, was born on Easter Sunday, 19 April 1795, at Delitzsch. In this town—then in Saxony, but now in Prussia—his father, Johann Gottfried Ehrenberg, was a municipal official, who was thrice married; his second wife being the mother of Christian Gottfried, who was the eldest son. His mother's maiden name was Christiane Dorothea Becker, and she was the daughter of the innkeeper of “The Red Lion” in Delitzsch. The forefathers of these Saxon Ehrenbergs were mostly millers, and they appear to have been unrelated to the noble family of the same name.

Lipid material occurs in the oocysts of Plasmodium in the form of small Sudano-phil granules, which appear to increase in size with the growth of the parasite. A diffuse Sudanophil material also appears at a later stage.

Phospholipid occurs at a certain stage of the oocyst, but later disappears altogether. It appears more quickly in some oocysts than in the others, found in the same infected gut.

The pre-erythrocytic schizonts of P. cynomolgi are found to contain abundant lipid material.

The erythrocytic stages of Plasmodium and Hepatocystis cannot be stained with the Sudan dyes, but the gametocytes of Hepatozoon infecting the blood corpuscles of the vertebrate hosts are found to contain abundant Sudanophil material.

Sudanophil material can be detected in the unsporulated oocysts of Eimeria stiedae, but not in the sporulated ones.

To investigate the phenomenon that PCR of Leishmania (V.) lainsoni minicircles using primers B1 and B2 gives anomalous small-sized products, unlike all other members of the Leishmania Viannia subgenus, cloned kDNA minicircles from L. (Viannia) lainsoni were sequenced using fluorescent dye terminator reactions. The sequence of L. (V.) lainsoni where the primer B2 would be expected to bind, was different from the other members of the L. Viannia subgenus, matching in only 7 out of 19 bases with the sequence of L. (V.) braziliensis at this position. The sequence obtained from the cloned minicircles enabled the design of a new primer which, when combined with B1, allowed the amplification of full sized minicircles in L. (V.) lainsoni, but not other members of the L. Viannia subgenus. Comparison of the sequence obtained for Leishmania (V.) lainsoni with other Leishmania minicircle DNA confirms that Leishmania (V.) lainsoni is more similar to members of the L. Viannia subgenus than to other Leishmania, but is distinctly different.