Cysticercosis is caused by infections with embryonated eggs of the tapeworm Taenia pisiformis. Knowledge of the genetic characteristics of T. pisiformis could be applied to study the epidemiology and transmission of this parasite. In this study, 61 isolates of intraperitoneal cysticerci from eight geographically distinct regions in Sichuan province, China, were subjected to a molecular analysis in order to determine their intra-regional genetic characteristics. Partial sequences of the mitochondrial cytochrome c oxidase subunit I (cox1, 1427 bp) and NADH dehydrogenase 1 (nad1, 738 bp) were concatenated. Five haplotypes were identified, and 89.04% of total genetic variation was found in collections of T. pisiformis isolates from a single region. According to the phylogenetic reconstruction, the T. pisiformis isolates from eight regions did not form geographical clusters. Our study highlights the genetic characteristics of T.pisiformis with the aim of accelerating the genetic research and control of cysticercosis.

The rat tapeworm Hymenolepis diminuta can bioconcentrate several elements to conspicuously higher concentrations than tissues of their definitive host. The main aim of this study was to locate parts of the tapeworm into which lead, cadmium, zinc, copper, manganese and iron are accumulated. Male Wistar rats were experimentally infected with H. diminuta and worms were exposed to two different forms of lead for 6 weeks through the oral exposure of their rat hosts. After the exposure period, the element levels were determined in the posterior and anterior proglottids of the tapeworm. In all cases, lead concentrations were higher in the anterior parts than the posterior parts. Concentrations of cadmium, copper, iron, manganese and zinc were also significantly higher in the anterior parts. Zinc concentrations showed an opposite trend, with higher zinc levels detected in the posterior part of the strobila, in the control group. The present study demonstrates that risk and essential elements are accumulated mainly into the anterior part of H. diminuta.

Neurocysticercosis is a parasitic disease caused by encysted larvae of Taenia solium in the human central nervous system. Cysts mainly affect the cerebral hemispheres, although they can also be found in ventricles, basal cisterns, and subarachnoid spaces, and rarely in the cerebellum. Given the impossibility of studying the disease in human patients, Cardona et al. (1999) developed a mouse model of neurocysticercosis, using Mesocestoides corti, a closely related cestode. This allows us to study the parasite–host relationship and the mechanisms involved in the disease, in order to improve the therapy. In this murine model of neurocysticercosis, the location of tetrathyridia in parenchyma, ventricles and meninges has already been reported. The aim of this work is to report the cerebellum as a new location for M. corti tetrathyridia in the murine model of neurocysticercosis. A murine model that reproduces the human pathology is essential to evaluate the symptomatology and response to drug treatment in experimentally infected mice.

Schistosomiasis is a disease caused by parasitic flatworms of the genus Schistosoma, whose diagnosis has limitations, such as the low sensitivity and specificity of parasitological and immunological methods, respectively. In the present study an alternative molecular technique requiring previous standardization was carried out using the polymerase chain reaction (PCR) for the amplification of a 121-bp highly repetitive sequence for Schistosoma mansoni. DNA was extracted from eggs of S. mansoni by salting out. Different conditions were standardized for the PCR technique, including the concentration of reagents and the DNA template, annealing temperature and number of cycles, followed by the determination of the analytical sensitivity and specificity of the technique. Furthermore, the standardized PCR technique was employed in DNA extracted, using Chelex®100, from samples of sera of patients with an immunodiagnosis of schistosomiasis. The optimal conditions for the PCR were 2.5 mm MgCl2, 150 mm deoxynucleoside triphosphates (dNTPs), 0.4 μm primers, 0.75 U DNA polymerase, using 35 cycles and an annealing temperature of 63°C. The analytical sensitivity of the PCR was 10 attograms of DNA and the specificity was 100%. The DNA sequence was successfully detected in the sera of two patients, demonstrating schistosomiasis transmission, although low, in the community studied. The standardized PCR technique, using smaller amounts of reagents than in the original protocol, is highly sensitive and specific for the detection of DNA from S. mansoni and could be an important tool for diagnosis in areas of low endemicity.

Nematodes of the family Thelastomatidae are parasitic in the alimentary tract of many arthropods, including Periplaneta americana L. In Meerut, Uttar Pradesh, India, two nematode species, namely Hammerschmidtiella indicus and Thelastoma icemi, belonging to this family have been reported. In the present study, the molecular phylogeny of these two nematode species was derived using small subunit (18S) sequence and secondary-structure analyses. The small subunit sequence analyses were carried out to explore the validation and systematics of these species. Phylogenetic analyses were performed for primary sequence data as well as using neighbour-joining and maximum-parsimony approaches. In contrast, the inferred secondary structures for the two species, using free-energy modelling, showed structural identities. As well as this, motif sequences were also found to be a promising tool for nematode species identification. The study provides molecular characterization based on primary sequence data of the 18S ribosomal DNA region of the nematodes along with secondary-structure data and motif sequences for inferences at higher taxonomic levels.

Twenty-three (9%) of 255 domesticated dogs surveyed in Lahore, West Pakistan, were blood positive for microfilariae. Twenty-one (8·2%) had either pure or mixed infections with Acanthocheilonema dracunculoides. Dirofilaria repens microfilariae were present in 4 dogs and one had Dirofilaria immitis microfilariae. A single adult A. dracunculoides was found from the hind leg of an autopsied dog with A. dracunculoides microfilariae. Microfilariae had a diurnal periodicity in this animal. There is only one previous documented report of A. dracunculoides adult worms from a dog in the Indian subcontinent, but it is possible that microfilariae earlier described from India under other names may also have represented this species.

To date, 34 species of the genus Homalometron (Apocreadiidae) have been described; five of them in Mexican fresh or brackish water fish, whereas five have been reported as parasites of members of the fish family Gerreidae. While sampling wildlife vertebrates during a field course of parasitology at the Los Tuxtlas Biological Station (Instituto de Biología, Universidad Nacional Autónoma de México) in Veracruz, specimens of digeneans were collected from the intestine of the stripped mojarra, Eugerres plumeri in Sontecomapan Lagoon. Specimens were studied morphologically and molecularly, and we discovered that they represented a new species of Homalometron. The new species is morphologically like the other four congeners in having three pairs of well-developed oral papillae on the oral sucker: Homalometron elongatum; Homalometron lesliorum; Homalometron carapavae; and Homalometron papilliferum. Here, we describe the newly discovered species, increasing our understanding about the parasite diversity of brackish water fishes of Mexico.

Genetic markers, DNA sequences and karyotypes, of some European lissorchiid species from their intermediate and final hosts were obtained to clarify controversial data about their life cycles and taxonomy, and to reveal phylogenetic affinities. The life cycles of three species have been confirmed for the first time based on molecular data. Comparative analysis of internal transcribed spacer 2 (ITS2) and partial 28S rDNA sequences has undoubtedly proven that cercariaeum of type-species of the genus Asymphylodora, Asymphylodora tincae, develops in pulmonate snails, Anisus vortex and Stagnicola palustris, but not in the genus Bithynia. The faucet snail, Bithynia tentaculata, serves as the first intermediate host for Parasymphylodora (=Asymphylodora) markewitschi and Parasymphylodora parasquamosa; adults of both species were isolated from the common rudd, Scardinius erythrophthalmus. It has also been confirmed that B. tentaculata serves as the second intermediate host for P. parasquamosa. Phylogenetic analysis supports the validity of the genus Parasymphylodora. Two species, Parasymphylodora markewitschi and P. parasquamosa, with cercariaeum belonging to the Parasquamosum group, are closely related and are being recovered as a well-defined evolutionary lineage in phylogenetic trees. A significant divergence between Parasymphylodora spp. and Asymphylodora spp. was revealed. The diploid chromosome set of P. markewitschi is composed of 14 chromosomes and does not show similarities with karyotypes of other lissorchiid species. Asymphylodora progenetica and Asymphylodora tincae share the basal diploid value of the family, 2n = 20, and reveal very close morphology of the corresponding chromosome pairs. Karyotypic similarities of these species are in accordance with molecular phylogenetic data. Thus, the available molecular and cytogenetic data support the assignment of P. markewitschi and P. parasquamosa to a separate genus, meanwhile, the assignment of A. progenetica to the genus Parasymphylodora was not justified.

Four muscle groups are responsible for the eversion and retraction of the apical denticles and enlarged pseudolabia in Skrjabinoptera goldmanae (Nematoda: Physalopteridae), which occurs in the lizards Chlamydosaurus kingii, Pogona spp. and Varanus gouldii in Australia. These muscles enable the nematode to bury its anterior portion in the gastric submucosa of its hosts. They comprise three sets which are derived from the somatic musculature and are inserted in the oesophagus and associated organs, and a fourth set of muscles which appears to be derived from the muscular oesophagus itself. These accessory muscle groups are described and illustrated, and from this their mode of action in everting and retracting the pseudolabia is derived. Possible selection pressures which led to their evolution are reviewed.

The structure and affinities of the progenctic larva of Echinobothrium reesae Ramadevi, 1969, are described and discussed.

A brief description has been given in an earlier paper (Goodey, 1943) of damage to tulip bulbs caused by the stem and bulb eelworm, Anguillulina dipsaci. In April, 1944, an opportunity arose, through the good offices of Mr. J. Oldnall Page, of Spalding, Lincs., of visiting a field in his district, in which eelworm-affected tulips were growing. Two of the varieties inspected were in flower and the other two were in an advanced bud condition. All four varieties exhibited marked symptoms of attack, and in the case of two of them in which there were a considerable number of plants, the damage caused to the blooms would entail a distinct financial loss to the grower. The largest planting consisted of the variety “ Rijnland,” the next largest was the variety “Wonderful.” In addition to these there were smaller plantings of “ William Copland ” and “ Mrs. Farncombe Sanders.” In all four varieties evidences of attack were apparent on leaves, stems and flowers and, in general, the writer can confirm the findings of Chitwood and Machmer (1942) on the symptoms manifested by the growing plant. They mention longitudinal splitting of leaf, flower-stem and corolla. It may be well, however, to attempt a more detailed description of the chief symptoms and types of lesion shown by affected plants: see also the two photographs accompanying this paper.

The ultrastructure of the spermatid and spermatozoon of Macracanthorhynchus hirudinaceus (Archiacanthocephala) was studied by means of transmission electron microscopy. The flagellum and nucleus in the spermatid gradually expanded simultaneously. The karyoplasm of the spermatid transformed into dense inclusions and a multibarrel structure, which were also found in the spermatozoan body. The multibarrel structure was located close to the flagellum and consisted of many irregular microtubes. The flagellum of the developing spermatozoon was observed in a concavity of the spermatid nucleus. The microtubule arrangement of the flagellum was ″9+2″. No mitochondria or acrosome were observed in spermatozoa.

In 1927 and 1928 Hiraishi published some observations which he had made on Ascariasis in swine in the absence of Vitamin A. He claimed that he had been successful in overcoming the resistance of the pigs to the human strain of Ascaris lumbricoides by lowering the vitamin A content of the diet and that he was able to produce much heavier infestations with Ascaris lumbricoides of swine origion in A-avitaminosed pigs. As all other factors were apparently controlled, he draws the conclusion that vitamin A has a direct bearing on the susceptibility of the pig to infestation with round worms. Unfortunately these publications are not readily available in England and only summaries of results have been available to the present writer. But from the data given and in comparison with the effect of the vitamins on Ascaridia (Ackert et alia, 1929 and 1931 a & b) and on hookworm (Foster & Cort, 1931 and 1932), these conclusions would seem to be justified.

As a result of complaints received from farmers as to the presence of parasitic worms in sheep, an attempt was made during the period October 1923 to September 1924 (inclusive) to ascertain the distribution and relative abundance of the more usual parasitic worms inhabiting the alimentary canal of sheep in North Wales. Regular collections were made from the following centres:—Pwllheli, Carnarvon, Bangor, Conway and Llandudno, with a few records also from Colwyn Bay, Bethesda, Menai Bridge and Denbigh. All the sheep examined were slaughtered for food purposes, practically the whole being obtained from slaughter houses. Almost all had grazed for considerable periods on the farms in the district mentioned, at elevations varying from sea level to 600 feet.

Experiments were performed to study the effect of age and lifespan on the infection success of Diplostomum spathaceum miracidia. Specimens of Lymnaea peregra and L. stagnalis were individually exposed to single miracidia of D. spathaceum of different ages under conditions of constant illumination at 20°C. The life-span of the free-swimming miracidium of D. spathaceum is 24 h at 20°C. It was observed that as the miracidium ages, its ability to successfully infect snails declines rapidly.

Homogenates of the metacercariae of Clinostomum complanatum showed two peaks for the hydrolysis of p-nitrophenyl phosphate at pH 4·5–5·0 and 11·0; specific activity at pH 5·0 was 0·017 µmol p-nitrophenol/mg protein/min and 0·0049 µmol p-nitrophenol/mg protein/min at pH 11·0 at 37°C. Maximal activities of acid and alkaline phosphatases were observed at 50° and 40°C respectively. Both enzymes reached maximal rates after 50 min of incubation. Linearity in enzyme activity was noticed with increasing homogenate concentrations for both enzymes. The Km for p-nitrophenyl phosphate was 1·1 mM with a Vmax of 0·018 units/mg protein for acid phosphatase and 1·6 mM with a Vmax of 0·0052 units/mg protein for alkaline phosphatase. Sodium arsenate and sodium fluoride inhibit and Mg++ and Co++ stimulate both enzymes. Polyacrylamide gel electrophoresis showed one cathodic band each for both the enzymes.

1. A precipitate was formed at the oral opening, excretory pore and anal opening of the fourth stage juveniles of O. columbianum in the presence of immune serum in vitro, causing their immobilisation and subsequent death in large numbers. The precipitates failed to appear on these juveniles in normal serum or in saline; nor did they appear on the third stage juveniles on incubation in immune sera. Apparently the excretory-secretory products of the fourth stage juveniles of O. columbianum serve as antigen and play an important role in the stimulation of antibodies in the host.

2. Inactivation of the immune serum did not destroy the precipitin type of antibody, nor was it affected when the immune animals had been treated with cortisone.

3. Immune serum from animals receiving multiple infections showed a higher antibody titre.

4. The possible way in which the antibody acts on the fourth stage juveniles, causing their immobilisation and subsequent death, is discussed.

Brachylaemus dasyuri (Johnston, 1912) is recorded from Thylacis obesulus (Shaw & Nodder, 1797) from Queensland. It is redescribed and Brachylaemus simile (Johnston, 1912) is confirmed to be a synonym.

A review is made of the species of Brachylaemus recorded from American and Australian marsupials. It seems probable that they have arisen from a common ancestral type parasite in an ancestral marsupial.

From the researches of Onchi and Nishio it is known that the encysted larva of Heterophyes nocens Onchi et Nishio is found in the Japanese mullet. H. nocens is closely allied to H. heterophyes v. Siebold, which is found commonly in. man, dog and cat in Egypt. It may be assumed that the larva of the Egyptian Heterophyes will be found likewise in certain fishes allied to the mullet. On the homeward voyage from my tour in Europe I examined some specimens of mullet in Port Said, for the purpose of finding the young larva in them, and was fortunate enough to discover encysted larva. I carried back with me some of these fishes fixed by formalin. After returning to Chosen (Korea) I examined the parasite, and found that it certainly belongs to a species of Heterophyes. Its morphological description is given in the present short communication.

Hexatylus viviparus, a spear-bearing nematode superficially resembling Aiiguillulina dipsaci, was originally described by the writer (1926) from a diseased potato tuber. In a second note published the same year (1926a), further details of its structure were given; the organisms in this case being obtained from a gladiolus corm affected with an internal soft rot.

Since the appearance of these papers the writer has encountered this species on several occasions both in potato tubers and gladiolus corms. The receipt of a gladiolus corm in February, 1937, the brown rotten centre of which contained numerous specimens of the worm, provided further material for detailed observations on the structure of the worms. Some of the decayed central tissues of the corm also served as an inoculum for the cultivation of the nematode, along with a fungus, on slope cultures of a malt extract agar. Subcultures from the original slopes have been made from time to time and on these the worms have been successfully maintained for more than twelve months.