A 30 kDa antigen was characterized as a hydrophobic polypeptide containing 16 amino acids and evaluated as a potential candidate vaccine against infection by Schistosoma mansoni. CD1 albino mice immunized at 0, 14, and 21 days with 25 or 50 μg of the 30 kDa antigen per mouse with and without alum developed high levels of IgG antibodies (predominantly IgG2a and IgG2b isotypes). When immunized mice were infected with 200 S. mansoni cercariae, the highest protection levels (61% and 65% reduction in worm burden in two separate experiments) were obtained using the 50-μg antigen without alum adjuvant. The granuloma size decreased to 10%, a non-significant level in mice immunized using alum adjuvant. The results demonstrate the ability of the 30 kDa antigen with and without alum adjuvant to protect mice against S. mansoni infection.

Metacercariae of the trematode Curtuteria australis (Echinostomatidae) accumulate in the foot of the New Zealand cockle Austrovenus stutchburyi, severely impairing the cockle's ability to burrow under the sediments. This results in increased predation by birds on cockles, and thus enhanced transmission rates of the parasite to its bird definitive hosts. This host manipulation by the trematode is costly: fish regularly crop the tip of the foot of cockles stranded on the sediment surface, killing any metacercariae they ingest. A second, previously undetected trematode species (characterized by 23 collar spines) co-existing with C. australis, has been found in the foot of cockles in the Otago Harbour, South Island, New Zealand. The relative abundance of the two species varies among localities, with the identity of the numerically dominant species also changing from one locality to the next. Both C. australis and the new species have a strong preference for encysting in the tip of the cockle's foot, where their impact on the burrowing ability of the host is greatest, and where they both face the risk of cropping by fish. Results indicate that these two species are ecological equivalents, and their combined numbers determine how the cockle population is affected.

The population biology of the fish acanthocephalan Acanthocephalus clavula was described from 161 wild brown trout, Salmo trutta sampled over a two-year period in Clogher Lake in the west of Ireland. Overall prevalence of the parasite was 86% and the mean abundance was 53 worms per fish. Despite the presence of large numbers of worms in the trout very few females (2%) attained full reproductive maturity. This suggests that trout is an accidental host. A sample of yellow eels, Anguilla anguilla was examined at a different time from the same lake. The prevalence of A. clavula was 97% and the average abundance was 8 worms per fish. In contrast to the situation in trout, the proportion of female worms attaining full reproductive maturity was 61% fulfilling the expected characteristic of a preferred definitive host. The possible explanations for the very high abundance of A. clavula in trout are discussed and include the influence of fluctuations in host populations, host diet and the absence of a potential competitor.

Multilocus enzyme electrophoresis was used to compare specimens of the parasitic nematode Cloacina obtusa from the stomach of the eastern grey kangaroo, Macropus giganteus and the western grey kangaroo, M. fuliginosus. Allelic variation among nematodes was detected at 17 (85%) of 20 loci, but there was only a single fixed genetic difference (at the locus for isocitrate dehydrogenase, IDH) between C. obtusa from M. fuliginosus and those from M. giganteus in areas where each host occurred in allopatry. However, this fixed difference was not apparent within the zone of host sympatry. Although electrophoretic data indicate genetic divergence among allopatric populations of C. obtusa in the two host species, the magnitude of the electrophoretic difference (5%) between these populations does not refute the hypothesis that C. obtusa represents a single species. The ’usual’ situation for parasitic helminths of grey kangaroos is that pairs of parasite species occur in the two host species. This situation differs for C. obtusa, where there has been a lack of speciation following a speciation event in its macropodid marsupial hosts. This finding suggests that a speciation event in the host does not necessarily lead to a speciation event for all its parasites and further highlights our lack of understanding of which processes drive speciation in parasites.

Alveolar echinococcosis (AE) is a helminth zoonosis which is encountered only in the northern hemisphere. In central France, the Auvergne region represents the most western and southern extension of this helminthiasis. In 1999, a human case of AE was diagnosed in the southern part of the Cantal department, where AE was supposed absent, and an epidemiological survey was subsequently carried out. The transmission of the zoonosis in the sylvatic and peridomestic definitive hosts was studied, as well as that in the rodent and human intermediate hosts. Eleven red foxes (Vulpes vulpes) were shot, and 50 fox faecal deposits were collected. Twelve farm dogs had their faeces taken by rectal touch, and four were checked after arecoline purgation. Optical detection of Echinococcus multilocularis worms was achieved on fox intestines after scraping, and also on dog stools after arecoline therapy. Coproantigen ELISA assay was performed for the 11 scraping products, for the 50 fox faeces, and for the 12 dog faecal samples. No adult AE agent was observed by microscopy, and the ELISA assay yielded positive results in one of 11 fox intestines, one of 50 fox faeces, and 2 of 12 dog faecal samples. Twenty-five small mammals were trapped, of which 19 were Arvicola terrestris water voles. One rodent liver exhibited a hepatic lesion consistent with AE. An epidemiological questionnaire was completed in 85 human volunteers, who were also serologically tested for AE. Only one (the case's husband) exhibited a Western-blotting pattern indicative of a low-grade AE infection. The results of this preliminary study suggested a slow AE extension to the south of Cantal department from the northern focus.

Two groups of Galba truncatula and two groups of Lymnaea natalensis were experimentally infected with Fasciola gigantica to determine if snail species had an influence on the redial burden and cercarial shedding of this trematode when snails of both species were infected with the same isolate of miracidia. In the two groups used for the study of redial burden, the total number of free rediae was significantly higher at day 49 post-exposure in L. natalensis than in G. truncatula. In the groups used for cercarial shedding, the life-span of cercaria-shedding snails and those of infected snails which died without cercarial emission, and the duration of the prepatent period were significantly longer in L. natalensis than those noted in G. truncatula. However, the mean numbers of shed cercariae did not significantly differ and showed no differences in their daily distribution throughout the shedding period. These results demonstrate that G. truncatula might be the principal intermediate host of F. gigantica in Egypt, at least in the areas where this lymnaeid species lives.

The helminth community of the wood mouse, Apodemus sylvaticus, in the Sierra Espuña was characterized after a complete analysis of its helminth community component and infracommunity structure relative to host age, sex and year of capture. The helminth community comprised 13 species: one trematode, four cestodes and eight nematodes. The cestode Pseudocatenotaenia matovi and the nematode Syphacia frederici were the most prevalent and abundant helminth species, respectively. Sixty four percent of mice analysed presented helminths with a direct cycle and 42% presented helminths with an indirect cycle. The helminth community presents a low diversity with infracommunities usually made up of only one or two helminth species. Host age and year of capture seem to play a major role in determining species richness and helminth diversity, but not in determining the abundance of helminths. Host sex does not seem to affect the infection rate nor the diversity. Further studies on more samples of wood mice and other small mammal species in this regional park are needed to explore any possible interactions between helminth communities in the host populations.

The seasonal cycle of the cestode Proteocephalus sagittus (Cestoda: Proteocephalidae) was studied for the first time in the stone loach Barbatula barbatula from the Haná River, Czech Republic. A total of 180 loaches were examined monthly from January to December 2001. The parasite occurred in loaches throughout the year but infection parameters differed significantly among seasons, with the highest values of prevalence and abundance from the late winter to the early summer. Parasite recruitment took place in the winter and early spring and the worms sexually matured in the late spring and early summer. In contrast to P. torulosus, the gravid worms of which laid eggs only at the end of the spring/beginning of the summer, gravid worms of P. sagittus were also found, although in low numbers, in the autumn and early winter. The rate of infection of loach with P. sagittus was neither dependent on the sex nor on the size of its fish host.

There are four species of ‘pygmaeus’ microphallids, namely Microphallus pygmaeus, M. piriformes, M. pseudopygmaeus and M. triangulatus (Trematoda: Microphallidae) which are parasites of marine birds and their sporocysts give rise to transmissible metacercariae inside littoral gastropods (mostly littorines). Universally primed polymerase chain reaction (UP-PCR) showed no apparent pattern between genetic diversity of the metacercariae as estimated by genomic banding profiles and their geographic region or molluscan host species. At the same time UP-PCR product cross-hybridization showed that M. pseudopygmaeus and M. triangulatus are genetically very similar, indicating that these taxa represent one species complex. In contrast, M. pygmaeus and M. piriformes are genetically well separated from each other and also from the pseudopygmaeus–triangulatus complex. Scanning electron microscopy of ventral spines, and analyses of spine angles and the number of teeth per spine, showed that all species differed significantly from one another. It was concluded that M. piriformes represents the original western member of the ‘pygmaeus’ group. Microphallus pygmaeus probably diverged from M. piriformes as it progressively specialized for sea duck final hosts. Microphallus pseudopygmaeus and M. triangulatus diverged from each other and the piriformes–pygmaeus ancestral line relatively recently. Microphallus pseudopygmaeus specialized for adoption of a wide range of gastropod host species and M. triangulatus developed morpho-functional specialization associated with final host exploitation.

Changes in the viability, infectivity and heat shock protein (Hsp) levels are reported in Trichinella spiralis first stage larvae (L1) stored in 199 medium for up to seven days at 37°C. These conditions induce stress that the larvae, eventually, cannot overcome. After three days of storage, the infectivity and viability were unchanged, although higher Hsp70 levels were observed. After this time, larvae gradually lost viability and infectivity, coinciding with a decrease in Hsp70 and Hsp90 and an increase in actin (a housekeeping protein). In addition, a possibly inducible heat shock protein, Hsp90i, appeared as constitutive Hsp90 disappeared. No significant changes in Hsp60 levels were detected at any time. These results suggest that heat shock proteins initially try to maintain homeostasis, but on failing, may be involved in cell death.

Clinical, parasitological and pathological responses of a tropical out-bred domestic rabbit to experimental Trichostrongylus colubriformis infection were used to evaluate its suitability as a laboratory host and model for studying the host–parasite relationships of T. colubriformis. In the first experiment, three groups each of 16, predominantly juvenile male, 8- to 10-week-old rabbits were given a single pulse infection with 500, 5000 or 25000 infective larvae (L3) of T. colubriformis, to represent low, medium and high levels of infection, respectively. A fourth group of 16 rabbits of similar age formed the uninfected controls. In the second experiment, two groups of 10 juvenile (8- to 10-week-old) and 10 adult (8- to 10-month-old) rabbits were similarly infected with 20000 L3, with appropriate naïve controls. Prepatency was 14 and 16 days and peak faecal egg counts occurred on days 24 and 20 after infection in young and adult rabbits respectively. Peak worm counts occurred on day 14 in both age groups and at all levels of infection. Subsequently, parasite burdens declined in a highly significantly dose- and age-dependent manner. At low and moderate levels of infection, approximately 83–98% of worms were recovered from the first 60 cm of the small intestine. Worm fecundity was also significantly influenced by host age and larval dose. Host age also had a significant effect on worm length. Infections with T. colubriformis were associated with a highly significant loss of body weight, accompanied by anorexia, diarrhoea and 25% mortality at high dose levels during the patent period of infection. There were no significant changes in packed cell volume and eosinophil counts at all ages and levels of infection but significant lymphocytosis occurred at the high dose level between days 7 and 21. Parasite-specific serum IgG responses were not related to worm burden. Overall, data showed that this miniature, docile and relatively inexpensive breed of rabbit is a potentially valuable laboratory host for studying T. colubriformis infections. The larval dose, duration of infection and host age were major determinants of host responsiveness to primary infections in this rabbit genotype.

The prevalence of helminths recovered from 108 birds representing eight species of Ciconiiformes from the Brazilian west-central region are presented. The digeneans Ascocotyle (Phagicola) longa, Clinostomum marginatum, Cotylotretus grandis, Ithyoclinostomum dimorphum, the nematodes Contracaecum multipapillatum, Desmidocercella ardeae, Eustrongylides ignotus, and the cestode Valipora mutabilis were identified. Contracaecum multipapillatum was the most prevalent species and E. ignotus the most pathogenic. Gross lesions due to infections with C. multipapillatum were characterized by ulcerative processes and hyperemia of the mucosa whereas those caused by E. ignotus consisted of perforations of the gastric mucosa and fibrotic tubular lesions in the gastric serosa. Histopathological examinations revealed necrosis and mixed leucocyte infiltrations and discrete compression of the mucosa in C. multipapillatum infections. Destruction of the mucosa and submucosa with the presence of fibrous capsules were observed in E. ignotus infections. Reports of accidental human infections, with severe clinical signs induced by these parasites, indicate the necessity of a proper evaluation of the pathogenicity of helminths of aquatic birds.

A case of intestinal anisakiasis caused by Anisakis sp. larva type I in a woman from Italy who consumed raw marinated anchovies, is reported. The diagnosis was based on the morphological features characteristic of anisakid larval stages, which were readily recognized in a large granuloma removed after emergency surgical treatment.

Polycephalic larvae of Taenia endothoracicus were found from naturally infected gerbils Meriones lybicus in a rural area of Arak, central Iran. A large cyst containing 19 protoscolices was located in the peritoneum, attached to the large omentum. The characteristics of the protoscolices and rostellar hooks confirmed the identification of these larvae as T. endothoracicus.

The effects of snail size on encystment of Echinostoma caproni cercariae in neonatal and juvenile Biomphalaria glabrata (NMRI strain) snails were studied. Encystment in neonatal (0.7–1.1 mm shell diameter) and juvenile (2–3 mm shell diameter) snails was compared 24 h post-infection (PI) following individual exposure of snails of each size to 1, 5, 10, 25 and 50 cercariae. Significantly more cysts were recovered from juveniles exposed to 1, 5, 10 and 50 cercariae than from neonatals with comparable exposure. Size of B. glabrata was a major factor in determining cyst burden in this planorbid. Survival of infected versus uninfected neonatals and juveniles was also examined for 7 days. Neonatals exposed to 10 cercariae showed a significant decrease in survival at 3, 6 and 7 days PI when compared to the uninfected controls. There was no significant decrease in the survival of juveniles exposed to 10 cercariae compared to uninfected controls at any time point. Snail size was a factor in mortality associated with echinostome cercarial penetration and encystment.

During routine parasitological surveillance and monitoring activities within a National Control Programme for control of human schistosomiasis in Uganda, it was noted that cattle grazing in a water meadow immediately adjacent to Tonya primary school, where the prevalence of intestinal schistosomiasis in children was in excess of 90%, were unusually emaciated. To test the hypothesis that there may have been an anthropozoonotic focus of Schistosoma mansoni within the local herd, a young female heifer, clearly emaciated and c. 8 months old, was slaughtered from which schistosome worms were later recovered by dissection. As female worms inspected by microscopy were not gravid, morphological identification proved inconclusive but analysis of cytochome oxidase subunit I (COI) and small subunit (SSU) ribosomal DNA sequences from these worms identified them as Schistosoma bovis Sonsino, 1876. This is the first substantiated report of S. bovis from Lake Albert, western Uganda. Further epidemiological surveys are needed to clarify the extent of bovine schistosomiasis within this region, particularly so since this lakeside plain has been earmarked as a future game reserve.

Clear spot lesions were formed on the liver surface in guinea-pigs repeatedly infected with swine lungworm, Metastrongylus apri. The largest lesion, measuring 0.25 cm in diameter, was hard and yellow and showed a large granuloma in the lobule. The nematode larva was located at the centre of the lesion. This finding is likely to be an example of erratic parasitism in guinea-pigs with metastrongylidiasis.

Elaphostrongylus cervi produces a subclinical cerebrospinal disease in many wild and domestic ruminants from Europe, North America and New Zealand and has recently been described in Spain. To determine some aspects of its epidemiology, 121 red deer (Cervus elaphus) from central Spain were sampled during 2000. The prevalence (7%) and mean worm burden (3.8 worms per brain) were similar to the values previously recorded in other European areas. The infection was only detected in young deer during the winter. The estimation of larval production in the faeces was not a reliable method of diagnosing E. cervi infection.