Variability of Schistosoma intercalatum eggs in shape and size, and their similarity to those of S. haematobium presented a problem of species identification when egg morphology was the diagnostic criterion used in a study of human schistosomiasis conducted on São Tomé and Principe. More than 2500 egg measurements were obtained by light micoscopy to gather data relating to size variability of S. intercalatum eggs, to evaluate whether factors such as age of host, sex of host and intensity of infection are correlated with variability, and the data were compared with previously published measurements on different isolates and strains of S. intercalatum: the range in length (104–203 μm) embraces most of the measurements reported in other studies of S. intercalatum eggs. There was no correlation either between age and sex of the host, or intensity of infection with variability of egg size. Comparison between measurements of the eggs of S. haematobium, S. intercalatum and S. bovis eggs are presented.

A partial immunocharacterization of oncosphere and metacestode antigens of Taenia solium was carried out and compared to antigens from other taeniid species. The results indicated that T. solium metacestode antigen contained epitopes cross reactive with rabbit anti-sera to adult and oncospheral stages of the parasite. Oncospheres, however, consisted largely of stage specific antigens. Western blot analysis indicated that T. solium and T. pisiformis shared several oncospheral antigens; however, this was not the case with T. solium and T. hydatigena. Western blot analysis showed a time-related increase in the number of molecules recognized by antibodies to T. solium oncosphere and metacestode antigens in pigs experimentally infected with T. solium eggs. Oncosphere specific antibodies were detected in pig sera one month after experimental infection whereas antibodies to cystic stage antigens were not present until the 3rd to 5th month post infection. Sera from neurocysticercotic patients as well as naturally infected cysticercotic pigs recognized high molecular weight antigens in the oncospheres.

There are about 70 species of capsalid monogeneans in the Benedeniinae worldwide but only about half are described from the diverse fish fauna in the Pacific Ocean. Up to 1992, only five species of benedeniines were known from Australia. Two potentially destructive species of benedeniines, Benedenia seriolae from Seriola lalandi and B. sciaenae from Argyrosomus hololepidotus from temperate Australian waters, are new host and geographic records for these monogeneans. A survey of some fishes from the Great Barrier Reef has revealed at least 15 undescribed species of benedeniines in addition to three species which have been described recently (B. lutjani, B. rohdei and Metabenedeniella parva). The few previous records for benedeniines from Australian fishes are probably the result of three factors. First, there have been relatively few careful studies of the external surfaces of fishes from Australia for monogeneans. Second, some benedeniines display a previously unsuspected specificity for particular external microhabitats on their hosts such as specific fins or sites previously unrecognized as microhabitats for monogeneans on the head of some species of fishes such as lip folds and branchiostegal membranes. Third, some benedeniines on the flanks and fins of some fish are extremely difficult to see because they are transparent and/or possess pigment spots throughout the body. Sometimes, benedeniines from colourful species of reef fish bear bright colours in their bodies. It is highly likely that these features serve as camouflage to conceal the parasites from predators such as cleaner organisms.

An examination of the effects of Pomphorhynchus laevis cystacanths on the haemolymph and midgut gland carbohydrate titres of its intermediate host, Gammarus pulex (Crustacea) was undertaken. In the haemolymph, infection with cystacanths did not alter the relationship between haemolymph carbohydrate titres and body wet weight. However, in the midgut glands, infection did alter the relationship between gammarid wet weight and titres of glucose and trehalose (P<0.05, Chow test). The linear relationship between gammarid size and midgut glycogen titre was also significantly altered by infection. Thus circulating carbohydrate titres are unaltered in infected gammarids but storage ones are. The changes in carbohydrate titres and the relationship between individual titres and body wet weight are discussed, especially regarding parasite index.

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.

The results obtained in a study of seroprevalence by means of ELISA and immunoblot with crude larval extracts of Anisakis simplex using 1008 human sera from Spanish people showing no clinical suspicion of anisakidosis are given. For the evaluation of the results obtained by ELISA the Diagnostic Index (DI) was used, as the ratio between the optical density resulting from the test serum and the optical density of the negative control. Forty-seven sera showed DIs between 1.5 and 2, and 14 sera were greater than 2. After comparison of the immunoblot analysis with the immunorecognition pattern of a human anisakidosis reference serum, a diagnostic criterion could be established for those sera that, at a 1/100 dilution, showed a DI by ELISA greater than 1.5. Seven of 14 selected sera with DIs in ELISA higher than 1.3 showed anti-Anisakis specific IgE antibodies by RAST fluoroimmunoassay.

The community structure exhibited by strongyloid nematodes from the large intestines of horses was examined using data from autopsies of 150 horses. Thirty-one species of nematodes were encountered, but they were not clearly divisible into core and satellite species. Multiple congeneric, consubfamilial and confamilial species were a prominent feature of the community and were more common than singleton infections. Multivariate analyses provided evidence of a stable community of helminths dominated by positive interactions but with few negative interactions, suggesting the absence of competition within the community.

The effect of zinc deficiency on the response of CBA mice to infection with the intestinal trematode Echinostoma caproni was examined. Young CBA mice were allocated to one of three dietary groups: a group fed a zinc deficient diet ad libitum, a control group pair fed a zinc sufficient diet and a control group fed a zinc sufficient diet ad libitum. The mice on the zinc deficient diet gained significantly less weight than the pair fed controls. In primary infections with six E. caproni metacercariae followed over a period of 128 days, zinc deficiency delayed worm expulsion. In addition, zinc deficiency resulted in a prolonged IgM response, a delayed IgG response and an increased IgA response towards the end of the experiment. Resistance to challenge infection day 21 following a primary infection with 25 E. caproni metacercariae was slightly, but not significantly, affected by zinc deficiency.

The structure of the metacercarial cyst wall and excystment in vitro were studied in the bucephalid digenean Bucephalus haimeanus. Optimum excystment occurred in a mixture of 1% trypsin and 1% bile salts at pH 7.8, following a 15 min pretreatment with 1% pepsin at pH 2.0. Enzymes (pepsin, trypsin) facilitated excystment, but were not essential, since some of the active metacercariae perforated the cyst wall in their absence. Other distinctive features were the weak development of the cyst wall, the occurrence of some excystment in strongly acidic media, ability to survive for at least 2 h in acidic media (pH 2.0) and total inactivity and failure to excyst in bile salts. The possible significance of these features is considered in relation to the location of the cysts in the liver of the second intermediate host, the common goby (Pomatoschistus microps), and conditions experienced by the cysts when the goby is eaten by the definitive host, the bass (Morone labrax). Excystment occurred readily at temperatures from 10 to 40°C, but percentage and speed of excystment were reduced at 5°C.

A study on the seroprevalence of toxocariasis, using ELISA with Toxocara larval excretory-secretory antigens, was carried out on human populations in two regions of Spain. Sera from a population of 195 children from Madrid and 143 children from Santa Cruz de Tenerife (Canary Isles), showed a prevalence of 0% and 4.2% respectively. Sera from a population of 272 adults from Madrid and 803 adults from Santa Cruz de Tenerife showed a prevalence of 3.6% and 17.4%. Reasons for these differences in the seroprevalence of Toxocara in the different age groups from the two regions are discussed.

Biological control of parasitic nematodes of domestic animals can be achieved by feeding host animals chlamydospores of the nematode-trapping fungus Duddingtonia flagrans. In the host faeces, D. flagrans develop traps that may catch nematode larvae. In experiments on agar, D. flagrans had a growth rate between 15 and 60 mm/week at temperatures between 20 and 30°C. The presence of nematodes induces the fungus to produce traps. The rate of trap formation in D. flagrans has an optimum at 30°C, producing 700–800 traps/cm2/2 days, when induced by 20 nematodes/cm2 on agar. Approaching 10 and 35°C the ability to produce traps is gradually reduced. The response of chlamydospore production on agar to changes in temperature is the same as that for trap formation. On agar, at 10, 20 and 30°C D. flagrans loses its trap inducibility after 2–3 weeks. During the ageing process, increasing numbers of chlamydospores are produced up to a certain limit. The time for reaching maximum chlamydospore concentration coincided with the time for loss of induction potential. The implications of these results in relation to biological control in faeces are discussed.

The morphology of the tegument of four microphallid metacercariae from the stage of invasive cercariae to their maturation as encysted metacercariae inside their crustacean second intermediate hosts is described. The tegument of the metacercariae developed surface lamellae and projections which, along with coated vesicles in the surface syncytium, indicated that the tegument had an absorptive function. The disappearance of secretory granules from the tegument at the same time as the appearance of the first cyst wall suggested that the tegument had a role in primary cyst production. Following this, the metacercariae continued to grow and seemingly retained their absorptive ability. The tegument was also involved in the transport of material into the perimetacercarial lumen prior to its eventual inclusion in the developing inner cyst layers. It appeared that this material originated in tegumental cells located amongst the parenchymal cells beneath the tegumental syncytial layer. On completion of the secondary cyst layers there was a gradual degeneration of structures associated with absorption and a progressive accumulation of dense discoid granules traceable to underlying tegumental cells. All four microphallid species (Maritrema arenaria, M. subdolum, Levinseniella brachysoma and Microphallus claviformis) demonstrated the same developmental pattern but the period spent in each stage differed depending on the time spent migrating to encystment sites. The pattern of tegumental development described is thought to be applicable to all microphallid metacercariae and possibly to other metacercariae which undergo growth and development in their second intermediate hosts.

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.

The tegument of Postorchigenes gymnesicus has been studied by scanning and transmission electron microscopy. The general body tegument is spinous and contains mitochondria, biconcave disc-shaped vesicles bounded by an unitary membrane and displaying a protein content, and scarce spherical bodies. The tegument covering specialized body regions is aspinous. Few vesicles were evident in the tegument covering the suckers and oesophagus, being more abundant in the metraterm and cirrus where the tegument is thicker. Laurer's canal has a thick tegument with sparse vesicles, mostly arranged close to the apical membrane. A direct association was evident between the basal lamina underlying the spines and the muscular subtegumental fibres, suggesting a motile character for the spine.

Mucosal glycoconjugates were examined in C3H mice and in hamster small intestines infected with Echinostoma trivolvis and in uninfected rodents, using periodic-acid Schiff (PAS) and high-iron diamine-alcian blue (HID-AB) staining and three different fluorescein-conjugated lectins: Triticum vulgaris agglutinin (WGA), Helix pomatia agglutinin (HPA) and Griffonia simplicifolia agglutinin (GSA-II). Lectin-labelling by electron microscopy was also undertaken with WGA and HPA lectin-gold probes. HID-AB stain demonstrated that the most mature goblet cells of the mouse villi contain sulfomucins, whereas those of hamsters contain sialomucins. The expression of lectin-binding sites and the intensity of the lectin binding in the small intestines were changed by echinostome infection. Specific differences in the reaction to mucin glycoproteins were clearly observed between the mouse and hamster intestines infected with E. trivolvis; lectin-binding to hyperplastic goblet cells and crypts in the infected mice increased, while no marked increase in the number of goblet cells and reaction to the glycoconjugates were observed in the infected hamsters. These findings indicate that the expression of terminal N-acetyl-D-galactosamine, sialic acid and N-acetyl-D-glucosamine increased in mucins secreted from hyperplastic goblet cells associated with E. trivolvis infection in mice. No marked increase in these glycoconjugates occurred in hamster infections. These findings reflect clear differences in infectivity of E. trivolvis in C3H mice versus hamsters.

Nucleotide sequence data from the Internal Transcribed Spacer 1 (ITS1) in the ribosomal RNA (rRNA) gene cluster were used to determine the utility of molecular data to discriminate species and genera of pseudocerotid turbellarians. We sequenced 388,379 and 415 bp from the ITS1 of Pseudoceros jebborum, Pseudoceros paralaticlavus and Pseudobiceros gratus respectively, to give an aligned sequence for this region of 421 positions. The nucleotide sequence of the ITS1 of Pseudoceros jebborum differed from that of Pseudoceros paralaticlavus by 6% (24/421 positions) and from that of Pseudobiceros gratus by 36% (152/421 positions). These results indicate that sequence data from the ITS1 will be a useful taxonomic tool to discriminate pseudocerotid flatworms.

When C57BL/6 mice were infected with Angiostrongylus cantonensis, the percentage of T helper (CD4+) cells and T supressor (CD8+) cells in peripheral blood increased weekly until the third and seventh week respectively, and then gradually decreased. C57BL/6 mice were depleted of CD4+ and CD8+ T cells by in vivo injection of anti-CD4 and anti-CD8 monoclonal antibodies, respectively, and then infected with A. cantonensis. There were significantly more and less worms recovered in the mice depleted of CD4+ and CD8+ T cells respectively than in undepleted mice. Discrete subpopulations of T cells from mice exposed to A. cantonensis for 3 weeks or 7 weeks were adoptively transferred to syngeneic recipients which were then given a challenge infection. Protection was mediated by a CD4+ T cell population present in mice after 3 weeks of infection but was not demonstrable with cells taken 7 weeks after infection. When CD4+ T cells obtained from 3-week infected mice were mixed with 5% CD8+ T cells obtained from mice infected for 7 weeks, no significant transfer of resistance was observed. Thus, immune responses to A. cantonensis in mice were regulated by discrete subpopulations of T lymphocytes.

Soil sampling was conducted within Peninsular Malaysia with the aim of recovering entomopathogenic nematodes (Steinernematidae and Heterorhabditidae). Extensive sampling was performed in the Cameron Highlands, which are climatically distinct from the lowlands, and characterized by lower temperature and humidity. The major areas sampled in the lowlands were at the campus of Universiti Pertanian Malaysia (orchards and plantations), Puchong (secondary rainforest) and along the east coast of the country. Entomopathogenic nematodes were recovered using the Galleria mellonella baiting method. Nematodes were recovered from 10% of the 425 samples assayed. Identifications, using a PCR method, revealed that the 21 identified steinernematids belonged to two different genetic types and that four out of the five heterorhabditids were Heterorhabditis indicus, the remaining heterorhabditid being a new species. The nematodes are currently being screened to evaluate their biocontrol potential for use in Malaysia against foliage-feeding lepidopteran pests of crucifers.

Seven free-living houbara bustards (Chlamydotis undulata macqueeni) wild-caught in the United Arab Emirates (UAE) were examined for helminth parasites. Of five birds investigated post mortem, one was free of gastrointestinal helminths. Two other birds expelled worms following clinical examination and anthelmintic treatment. This is the first report of the parasites of free-living, as opposed to captive, houbara bustards in the UAE. In infested wild birds, fewer species of helminths were recovered than had been found in captive birds and those species present had also been found in captive houbaras. Despite heavy worm burdens, the infested birds were in good condition. Two species of cestodes (Otiditaenia conoideis, Hispaniolepis falsata), two of acanthocephalans (Centrorhynchus lancea, Mediorhynchus taeniatus) and two of nematodes (Hartertia rotundata, Allodapa sp.) were recovered. Histopathological examination of tissue samples from the intestine of three birds revealed no significant pathological changes attributable to the presence of parasites but only localized responses at the sites of parasite attachment.