The serum antibody response in golden hamsters (Mesocricetus auratus) infected with the intestinal trematode Echinostoma caproni was examined with ELISA, SDS-PAGE and Western blot, and IFAT techniques. All methods showed that the hamsters responded slowly but developed a clear positive humoral response to the infection. In most hamsters, an antibody response to infection could not be detected earlier than 11–13 weeks after infection with 6 or 25 metacercariae, and responses were weak when compared to previous results from mice infected with the same parasite. IFAT with positive hamster sera on live juvenile E. caproni showed only fluorescence at the posterior tip, which is a different pattern from that seen using sera from infected mice, indicating a different response to antigens on the juvenile parasites by these two hosts. The results are discussed in relation to the limited selfcure and development of resistance which is observed in golden hamsters infected with E. caproni.

Fifty-nine of 60 (98%), 6-month-old male golden hamsters, Mesocricetus auratus, fed 15 (group A). 50 (group B), or 200 (group C) metacercarial cysts of Echinostoma caproni (Digenea: Echinostomatidae) were infected 7–34 days postexposure. The mean number of worms recovered in groups A, B and C were 9, 10, and 50, respectively. The percentage recovery was significantly different between group A (63%) and groups B (21%) and C (23%). The intestine was divided into three equal regions (I, II, III). Worms from group A were located in segments II and III of the small intestine whereas worms from groups B and C were distributed in all three segments. The body area, ovarian and testicular areas of worms from group A were greatest, followed in decreasing order by body and gonadal areas of worms from groups B and C. Echinostoma caproni eggs were found in the faeces of all the hamsters examined from groups A, B and C by days 9, 10 and 11, respectively. Physical damage occurred at the site of attachment of the echinostome. Pathological observations indicated the presence of enlarged lymphatic nodules with lymphocytes being the primary cellular infiltrate at the site of parasite attachment.

The karyotype of Isthmiophora melis (Trematoda:Echinostomatidae) is described. The chromosome number in the diploid cell is 2n = 20. The absolute (La) and relative (Lr) lengths of the chromosomes, as well as the centromere position (Ic), are determined. The differences in length between the adjacent chromosomes in the ordered series are not great, with the exception of chromosome 1 which occupies 20.58% of the genome length. This chromosome is metacentric, with lightly stained and elongated centromere region with Giemsa staining. Chromosome 7 is submetacentric. Chromosomes 2 to 6 are defined as telo-subtelocentric, while chromosomes 8 to 10 are subtelo-submetacentric. The fundamental number of arms in the I. melis karyotype is NF-22.

Experimental infections of the marine topshell Gibbula umbilicalis with Lecithochirium furcolabiatum (Digenea: Hemiuroidea) have allowed the development of a model system which will enable further studies of the molluscan host response. The long-lived intertidal prosobranch host is easily maintained in the laboratory, and experimental infection rates of 98% were consistently achieved. The miracidium and mother sporocyst have been studied at both light and ultrastructural levels, providing the first account of the morphology of these stages in Hemiuridae. The ingested egg hatches within the host intestine, treatment with L-cysteine and alkaline pH stimulating miracidial emergence in vitro. The general body surface of the miracidium is devoid of spines or cilia, the latter being restricted to four plates near the anterior extremity. The miracidium swims actively prior to penetration of the gut wall, the sporocyst being released from the miracidial epidermal Coat within the haemocoel. Within 5 weeks of infection, the filamentous mother sporocyst Contains 1 to 3 oval germ balls, daughter sporocysts being recorded free within the digestive gland haemocoel 7 weeks later. Twenty three weeks after ingestion of eggs, the daughter sporocyst extends into the host gill filaments, containing cystophorous cercariae ready for emergence.

Scanning and transmission electron microscopical obervations were made on the tegument of excysted metacercariae and adults of the paramphistome. Zygocotyle lunata (Digenea: Trematoda). In accord with other paramphistomes studied, this species lacks spines and mitochondria in the tegumentary syncytium and associated cytons. The newly excysted metacercarie, which possessed relatively few tegumental papillae, were cylindrical in comparison to adults which were distinctly flat. The adults had large numbers of tegumental papillae in the region of the oral sucker and acetabulum.

During the 1990 grazing season, ants found attached to plants were collected from sheep pastures at monthly intervals and examined for Dicrocoelium metacercariae. The species Formica pratensis and F. rufibarbis showed average metacercarial intensities of 76 and 38 respectively. In addition to the ant species, the intensity of infection was found to be dependent on the length of the ant. The volume of metacercarial cysts was influenced by the intensity per ant relative to ant length but not by the ant species or the time of ant collection.

A description is given of three contrasting adhesive attitudes exhibited by three species of capsalid monogeneans from the gills of three different species of teleost fish from Heron Island, Queensland, Australia. The proximal end of the primary lamella of the coral trout, Plectropomus maculatus has a wide inner border, free from secondary lamellae, on each flat face. The haptor of Trochopus plectropomi is small enough to attach to this flat surface without folding. Benedenia sp. 1 attaches itself to the gills of stripey, Lutjanus carponatatus, by folding the haptor longitudinally around the inner edge of the primary lamella. Most specimens of T. plectropomi and all specimens of Benedenia sp. 1 were orientated with the anterior end projecting towards the tip of the primary lamella. Benedenia sp. 2 generally prefers relatively flat surfaces in the gill chamber but is more versatile in its choice of attachment sites on its host, the blacktip cod, Epinephelus fasciatus; two specimens were attached to the gill arch, one to a gill raker and one to the dorsal pharyngeal tooth pad.

Two cases of intestinal obstruction due to Ascaris lumbricoides infection are reported from Ishaka Adventist Hospital, in south western Uganda. One was a male aged two and a half years and another was a female aged twenty. They were both treated surgically with good results. A review of the literature also revealed that intestinal obstruction due to A. lumbricoides is a common complication, though other surgical and nutritional complications also seem to be common, they are less reported.

In the present communication we have studied the isoenzymatic pattern activity of the glucose 6-phosphate dehydrogenase (G6PD) in Oesophagostomum venulosum, Trichuris ovis and T. suis, parasites of Capra hircus (goat), Ovis aries (sheep) and Sus scrofa domestica (pig) respectively, by polyacrylamide gel electrophoresis. Different phenotypes have been observed in the G6PD isoenzymatic pattern activity in males and females of Oesophagostomum venulosum. Furthermore, G6PD activity has been assayed in Trichuris ovis collected from Ovis aries and Capra hircus. No differences have been observed in the isoenzymatic patterns attending to the different hosts. All the individuals exhibited one single band or two bands; this suggests a monomeric condition for G6PD in T. ovis. In T. suis the enzyme G6PD appeared as a single electrophoretic band in about 85·7% of the individuals.

Stomach intubation is the most common method used in the experimental infection of animals with Angiostrongylus cantonensis. In order to compare the effectiveness of other possible transmission methods, groups of BALB/c mice were given infective third-stage larvae of A. cantonensis by different routes including intraperitoneal or subcutaneous injections, and penetration of anal mucosa, vaginal mucosa, conjunctival mucosa, lacerated skin, unabraded skin, foot pad and tail skin, while stomach intubation was used as control. Recovery of fifth-stage larvae was higher in mice inoculated with third-stage larvae subcutaneously. Successful infections were established through all experimental transmission routes except tail skin penetration. This study suggests that oral infection may not be the only route for the transmission of human angiostrongyliasis, and subcutaneous infection may be a better method for experimental infection.

Onchocerca lienalis microfilariae (mf) were cryopreserved in liquid nitrogen within skin-snips using methanol as a cryoprotectant and their viability evaluated and compared to mf cryopreserved free of host tissues using ethanediol as a cryoprotectant. Despite an initial delay in emergence, the methanol technique did not significantly affect the total numbers of mf emerging from skin-snips of various sizes (3·3–59·81 mg) compared to untreated controls over a 6 h period. Following thawing, the initial motility index (MI) scores of mf cryopreserved by either method were not significantly different from untreated controls; however, over a period of 15 days in culture the MI scores of both cryopreserved groups showed a small but significant overall decline, with the methanol technique producing the lowest scores. These changes in motility levels correlated with the numbers of mf which developed to the infective stage following intrathoracic injection into Simulium ornatum, although this ability to develop was a much more sensitive measure of parasite viability; compared to untreated control recoveries of 3rd-stage larvae, 63·9–71·7% (ethanediol technique) and 34·2–36·9% (methanol technique) of this number were recovered from cyropreserved groups. There were no significant differences in the lengths of infective larvae recovered from the insect heads from each treatment group, nevertheless there were higher numbers of 2nd-stage larvae recovered from the cryopreserved groups compared to the untreated controls. The methanol technique has the advantage of being easier to carry Out under field conditions, while parasite viability is significantly better using the ethanediol technique.

A method for hatching second-stage larvae of Toxocara canis is described. Whole adult worms are processed by centrifugation in the presence of hypochlorite which allows the grinding step to be eliminated. The technique is more rapid and a high yield is obtained.

Of 756 dog faecal deposits collected from the road side and public places in five Jordanian Governorates 466 (61·6%) harboured parasite ova, oocysts and/or larvae. Of these, 67·7%, 26·8%, 4·1% and 1·4% revealed one, two, three and four different types of parasite ova, oocysts or larvae in the same sample, respectively. Examination of the infected samples revealed that 44·1% contained taeniid ova, 19·8% Dipylidium caninum, 19% Toxocara canis, 8% Sarcocystis spp. oocysts, 5% hookworm larvae, 1·5% Diphyllobothrium latum, 0·1% Capillaria spp. and 0·1% Trichuris vulpis eggs.