An experimental Taenia crassiceps mouse model was used to assess the role of Taenia solium metacestode factor (Fac) in human neurocysticercosis. Intraperitoneal infection with T. crassiceps metacestodes or subcutaneous inoculation with a T. crassiceps metacestode factor (Fac) produced significant impairment of performance (learning) in the Barnes maze and induced bilateral hippocampal sclerosis in mice. Several staining techniques revealed important cell dispersion, extensive apoptosis and cell loss in the dentate gyrus, hilus and CA1-CA3 regions of both hippocampi, as well as intense deterioration of the adjacent cortex. An outstanding disruption of its histoarchitecture in the surrounding tissue of all these regions and apoptosis of the endothelial cells were also observed.

Moaciria sphenomorphi n. sp. is described from the skink Sphenomorphus gracilipes, Moaciria butleri n. sp. from the elapid snake Pseudechis australis (both from Western Australia), and Moaciria etnae n. sp. from the python Liasis childreni from Queensland. These species differ from one another and from M. alvarengai and M. icosiensis principally in the number and disposition of body and caudal papillae, and from M. freitasi in possessing caudal alae. M. butleri and M. etnae also differ from the other species in possessing a conspicuous three-pointed internal lip tooth, and all three new species possess a small median papilla within the posterior rim of the precloacal sucker.

In this study we examined trematode and nematode lung helminths commonly found in two species of host ranid frogs for competitive interactions. We examined 147 adult (breeding and non-breeding) and juvenile northern leopard frogs, and 84 breeding male wood frogs in Bishops Mills, Ontario for Haematoloechus spp. (Trematoda) and Rhabdias sp. (Nematoda) infections. A strong negative association between phyla of helminth was observed in breeding and juvenile northern leopard frogs, and also in breeding wood frogs, but not in non-breeding adult northern leopard frogs. Few hosts carried both types of worm concurrently. Thirteen northern leopard frogs carried dual infections, while 77 carried only one phylum of helminth. Twenty-seven wood frogs carried dual infections, while 54 carried only one phylum of helminth. We also observed spatial segregation of the two phyla in host lungs. Our study informs future research on the dynamics of interactions among lung helminths in these two host species.

During the intramolluscan larval development of Schistosoma haematobium (Algerian strain) in Bulinus truncatus, two replication processes of daughter sporocysts occur. Replication by direct sporocystogenesis appears more important than sporocystogenesis post cercariogenesis. These mechanisms assure a periodic renewal of the sporocyst stock in the snail host and seem to be synchronized with the development of cercarial generations. The succession of several generations of cercariae is responsible for the alternation of high and low periods of productivity.

The scheme proposed for the intramolluscan development of S. haematobium is compared with those described for S. mansoni and S. bovis and interpreted in terms of demographic strategies adapted to a better exploitation of the snail host.

Dexamethasone, a known immunosuppressant, was administered by bath or injection to Atlantic salmon Salmo salar (Conon stock) to study if this treatment could affect the susceptibility of fish to infections with a Danish strain of Gyrodactylus derjavini (Monogenea). Three groups of S. salar (Conon stock) were immersion treated either with 10, 60 or 240 μg dexamethasone l-1 water, respectively. In addition, one group (positive control) was treated intraperitoneally with 200 μg dexamethasone per fish and one negative control group was kept untreated. A single G. derjavini parasite was placed on the anal fin of each fish and the infection was subsequently monitored weekly for 6 weeks. An increase in parasite populations on the salmon was positively correlated with the amount of immunosuppressant used. Infection levels in the group immersion treated with dexamethasone (240 μg l-1 water) and in the i.p. treated positive control group were significantly higher compared to the untreated control group.

Parasite heterogeneity is thought to be an important factor influencing the likelihood and the dynamics of infection. Previous studies have demonstrated that simultaneous exposure of hosts to a heterogeneous mixture of parasites might increase infection success. Here this view is extended towards the effect of parasite heterogeneity on subsequent infections. Using a system of the tapeworm Schistocephalus solidus and its copepod intermediate host, heterogeneity of the tapeworm surface carbohydrates is investigated, i.e. structures that are potentially recognized by the invertebrate host's immune system. With lectin labelling, a significant proportion of variation in surface carbohydrates is related to differences in worm sibships (i.e. families). Tapeworm sibships were used for experimental exposure of copepods to either homogeneous combinations of tapeworm larvae, i.e. worms derived from the same sibship or heterogeneous mixtures of larvae, and copepods were subsequently challenged with an unrelated larva to study re-infection. Contrary to expectation, neither an effect of parasite heterogeneity on the current infection, nor on re-infection were found. The effect of parasitic heterogeneity on host immunity is therefore complex, potentially involving increased cross-protection on the one hand, with higher costs of raising a more heterogeneous immune response on the other.

Eleven male two-month-old Holstein calves were used to determine the pathological changes induced by a Cooperia punctata infection. After weaning, ten calves received a single oral dose of 45,000 C. punctata infective larvae. One calf remained as a non-infected control. Groups of two calves were killed on days 7, 14, 21, 28 and 35 post-infection (p.i.) for determination of worm burdens and histopathological evaluation. The small intestine was sub-divided into three sections of approximately equal length, and representative samples of mucosa were fixed in 10% formalin, cut, and stained with haematoxylin-eosin. Samples of intestinal contents and mucosal digests were taken and fixed in 10% formalin for an estimation of total worm burdens. An increase in the number of adult parasites and a decrease in the number of larvae were observed with time (P<0.001). A higher concentration of worms was found in the first segment of the small intestine during the five weeks of observation. Histology showed larvae in the intestinal mucosa on day 7 p.i., with a discrete increase in the cellular response. Adult worms and a marked cellular infiltrate with eosinophils and neutrophils were present on day 21 p.i., and these persisted until day 35 p.i. Microcysts resulting from worm destruction were observed from day 21 p.i.

In this study a new species of nematode, Iheringascaris goai n. sp., is reported from two fish hosts, including silver whiting, Sillago sihama, and spotted catfish, Arius maculatus, caught off the Central West Coast of India at Goa. The new species can be differentiated morphologically from I. inquies, the most closely related species collected from cohabiting marine fish. The distinguishing characteristics are distinct cuticular striations, a unilateral excretory system, the presence of dentigerous ridges on the inner margin of the lips and the ratio of oesophagus to body length. In males, the ratio of spicules to body length is higher and the number of pre-anal papillae is less in comparison to those in I. inquies. In addition, the tail curves ventrad in males, while in females, the vulva is post-equatorial. The sequence alignment of 18S rDNA and cytochrome c oxidase subunit I with sequences of known species selected from the same superfamily shows a significant difference. The morphological and molecular differences reported here can, therefore, be used to assign the specimen to a new species.

The intestinal morphology or rats given one, 10 or 100 cysticercoids of Hymenolepis diminuta was examined by scanning electron microscopy. The presence of this tapeworm causes extensive villous atrophy and fusion. The most extreme changes in mucosal architecture were observed adjacent to the mature proglottides of the worm and in these areas the villi were reduced either to flattened plate-like structures or to low irregularly shaped undulations. The presence of one large H. diminuta resulted in more severe pathological damage than caused by several smaller worms. Colonization of the upper region of the ileum by long filamentous bacteria was also observed in rats infected with H. diminuta.

Two members of a collection of the South American rodent Viscacia viscacia received by the Zoological Society of London, died early this year, one of them about 10 days after arrival at the Gardens. At the post-mortem examination both were found to have the alimentary canal heavily parasitized with Trichostrongylid nematodes. In the stomach there occurred Graphidioides rudicaudatus and Trichostrongylus retortæformis, whilst in the small intestine there were a few specimens of Trichostrongylus retortæformis and large numbers of the worm which forms the subject of the present paper. To naked eye examination of the intestinal wall the worms appeared as small bright red spots about the size of a pin's head and it could be seen that each was spirally coiled.

Seven specimens of this new species were collected from the intestine of a freshwater turtle, Trionyx triungnis (═T. nilotica) in the Sudan.

These are lanceolate worms which gradually taper to rounded ends, with a length of 2⋅5–2⋅9 mm. and a width of 0⋅6–0⋅9 mm. The cuticle is invested with scales, dense in the anterior half of the worm, but becoming more and more sparse towards the caudal end. The oral sucker is large, measuring 0⋅23–0⋅27 mm. in diameter and is about one and a half times the diameter of the ventral sucker which measures 0⋅14–0⋅17 mm. in diameter. Both suckers lie in the anterior half of the body. The mouth is subterminal and leads to a pharynx which is stout, 0⋅7–0⋅8 mm. by 0⋅11–0⋅12 mm., and leads to a long oesophagus of 0⋅25–0⋅32 mm. in length. The caeca terminate at the posterior border of the posterior testis or slightly anterior to it.

Observations on infection and the development of F. gigantica (W. African strain) in the susceptible L. natalensis and in the less susceptible mature L. rufescens (from Pakistan) and the histological study of the two species of snails at various stages of development of the contained parasite, revealed that,

The miracidia appeared to take a longer time to start penetrating the less susceptible host.

There was no significant tissue reaction even in L. rufescens to the development of the sporocysts. The development of the sporocysts which were embedded in denser tissues of the snails was apparently retarded in both the species of snail.

During the course of some anthelmintic tests carried out during June, 1949, it was necessary continuously to feed 4 per cent, phenothiazine to pheasant poults in the daily mash, which they ate without any obvious distaste and grew reasonably well. The birds were a mixture of several varieties of Phasianus colchicus, including some Formosan and Korean hybrids. These latter birds have a light coloured plumage and it was soon noticed that the feathers were darkening. The change was obvious less than 86 hours after the first experimental feeding. All the birds were therefore examined and it was found that all were similarly affected though it was less obvious among the melanistics and blacknecks, which have a darker plumage. The leg scales too had taken on a distinct dark green hue, and this became more intense as the tests proceeded; the pigmented feathers assumed a fiat brownish colour, while the filoplumes are distinctly red.

Although outbreaks of trichinosis in Great Britain have been sporadic, the present investigation shows the incidence of Trichinella spiralis in man in Southern England to lie between 7.9% and 13.7%, the average incidence being 10.8%. The condition of the larvae, either free or in thin- or thick-walled cysts recovered by the “digest” technique, indicated that the infections were of varying ages, from recent to those of many years standing. In six cases there was definite evidence of the presence of both recent and old infections.

A preliminary parasitological and malacological survey was effected in rural communities of some Local Government Areas (LGA) in Plateau State, Nigeria, to estimate the prevalence of urinary schistosomiasis and identify active transmission foci. Out of 2888 persons examined in six LGAs, 1381 (47.82%) were excreting eggs of Schistosoma haematobium in their urine. Prevalence rates did not vary significantly (P > 0.05) between the LGAs: Pankshin (62.4%), Shendam (40.2%), Qua'an-Pan (22.9%), Langtang South (45.4%), Langtang North (58.8%) and Wase (50.0%). Infection rates were significantly different (P < 0.001) between the sexes. Many water bodies in the study communities were colonized by infected Bulinus snails. Snail infection rates varied significantly (P < 0.001) between the dry and wet seasons. A positive correlation was observed between snail infection rates and the prevalence of S. haematobium.

1. The results of post-mortem examinations of 590 dogs and 185 cats in Shanghai are reported.

2. 88% of the dogs and 97% of the cats were infected with one or more species of helminthic parasite. The cats tended to harbour a larger number of species per animal than the dogs.

3. Infections with trematodes were very common, especially Clonorchis sinensis which was present in 79% of the cats.

4. There was a comparatively low incidence of infection with Ancylostoma caninum.

5. Prohemistomum industrium, and Echinostoma ilocanum, rare parasites of the dog, occurred.

6. The following parasites are recorded in their hosts for the first time in China.

1. Chlamydonema praeputialis in the dog.

2. Cylicospirura subaequalis in the cat.

3. Metorchis albidus as a natural infection in the dog.

Groups of 10 Mongolian gerbils. Meriones unguiculatus, were vaccinated with 1,500 gamma-irradiated Trichostrongylus colubriformis infective larvae (L3) or with non-irradiated larvae. 25 days later five gerbils from each group were necropised and the remaining gerbils challenged with 1,500 non-irradiated T. colubriformis infective larvae. Systemic, local intestinal and coproantibody levels were compared in each group of gerbils 25 days after vaccination and 26 days after challenge. Strong local intestinal and faecal antibody responses were detected. Coproantibodies reflected antibody levels in the intestinal contents and in mucosal extracts. The results gave further support to the view that coproantibody measurements provide a sensitive index of immunity at mucosal surfaces to intestinal parasites.

Antibody responses against crude antigens and the two (Em18 and Em16) epitopes of Echinococcus mulfilocularis were analysed by Western blotting using sera from the wild vole, Clethrionomys rufocanus bedfordiae (Crb), which were captured in Hokkaido, Japan and found to have been naturally infected with eggs, and compared with those in patients of AHD and mice experimentally infected with protoscoleces of this parasite. Antibody responses in the wild vole were demonstrated most clearly with anti-Crb-IgG antiserum but more faintly with anti-rat-IgG antiserum and poorly with anti-mouse-IgG or anti-human-IgG antisera or Protein G. Although only two serum samples of the wild vole found naturally infected were analysed, antibody responses against Em18 and Em16 in these voles appeared to be similar to those in AHD patients but differed from those in mice.

Adult Strongylus vulgaris, collected from the caecum of infected horses and embedded in paraplast using standard methods, were sectioned for immunohistochemistry (IHC) studies. Antibodies were raised in rabbit against the excretory–secretory product (ESP) and against two constituent protein bands (28–30 kDa). The use of sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), enzyme-linked immunosorbent assay (ELISA) and immunoblotting indicated the immunogenicity of ESP and of the subunits (28–30 kDa). In ELISA, both rabbit hyperimmune sera recognized the ESP and (28–30 kDa) bands consistently and strongly. Both hyperimmune sera recognized most ESP subunits (80, 60, 54, 42, 35, 30, 20 and 15 kDa) in immunoblots. IHC, using light microscopy, suggested that the following worm tissues reacted strongly and positively with both antisera: amphids, tooth core, intestine, excretory gland and ducts, and hypodermis. Thus, either these are antigen-producing tissues, or antigens sharing common epitopes occur in them. The following tissues reacted weakly: body cuticle, buccal capsule cuticle, oesophagus, and also somatic muscle (non-contractile portion) perhaps due to diffusion of antigen from adjacent tissues. Preimmune serum gave a negative reaction with most worm tissues.

The life-cycle stages of Pleurogenoides malampuzhensis sp. nov. infecting the Indian bullfrog Hoplobatrachus tigerinus (Daudin) and the skipper frog Euphlyctiscyanophlyctis (Schneider) occurring in irrigation canals and paddy fields in Malampuzha, which forms part of the district of Palakkad, Kerala, are described. The species is described, its systematic position discussed and compared with the related species, P. gastroporus (Luhe, 1901) and P. orientalis (Srivastava, 1934). The life-cycle stages, from cercaria to egg-producing adult, were successfully established in the laboratory. Virgulate xiphidiocercariae emerged from the snail Digoniostoma pulchella (Benson). Metacercariae are found in muscle tissues of dragonfly nymphs and become infective to the frogs within 22 days. The pre-patent period is 20 days. Growth and development of both metacercariae and adults are described.