The freshwater snail, Bithynia tentaculata (Gastropoda: Prosobranchia), is frequently found in gravel pits and its role in the transmission of larval digeneans was assessed in one of these unstable water bodies from the Lower Thames Valley (UK) from June 1982 to December 1984. Eight species of cercarial and five species of metacercarial infections were reported from B. tentaculata, with up to 7.7% and 4.7% prevalence of infections, respectively, occurring in the snail, making it the most important host at this site. Seasonal peaks in cercarial infections occurred in late autumn/early winter but little seasonality was apparent in the occurrence of metacercarial infections. The life history characteristics of both hosts and parasites, which can affect intramolluscan digenean dynamics, are discussed.

The fungus, Duddingtonia flagrans, is able to trap and kill free-living nematode larvae of the cattle parasite Cooperia oncophora when chlamydospores are mixed in cattle faeces. Isolates of Bacillus subtilis (two isolates), Pseudomonas spp. (three isolates) and single isolates of the fungal genera Alternaria, Cladosporium, Fusarium, Trichoderma and Verticillium were isolated from cattle faeces and shown to reduce D. flagrans growth on agar plates. When these isolates were added to cattle faeces containing D. flagrans and nematode larvae of C. oncophora, developing from eggs, none of the isolates reduced nematode mortality attributed to D. flagrans. Similarly, the coprophilic fungus Pilobolus kleinii, which cannot be cultivated on agar, also failed to suppress the ability of D. flagrans to trap and kill developing larvae of C. oncophora. Increasing chlamydospore doses of D. flagrans in faecal cultures resulted in higher nematode mortality. Thus, no evidence of interspecific or intraspecific competition was observed. The consequences of these findings are discussed.

A survey of gastro-intestinal helminth communities of Gallotia stehlini (Sauria: Lacertidae) from Gran Canaria island (Canary Archipelago, Spain), was conducted to determine the prevalence, abundance and species diversity of intestinal parasites in these lizards. Pharyngodonid nematodes were the most common intestinal helminths, three species being Gallotia specialists. Helminth infracommunities of G. stehlini were rich and appear to be closer to the interactive end of the continuum isolationist–interactive helminth communities, according to the high values of helminth diversity. It is the first case of a saurian reptile showing this kind of diverse helminth infracommunity, produced by a large size, a wide-ranging plant diet and exposure to helminths with direct life-cycles.

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 sensitivities of the Knott's test (four 20-μl sediment aliquots), quantitative buffy coat capillary tube method (QBC tube, 111 μl of whole blood) and direct blood smear (DBS, 20 μl of whole blood) were evaluated for the detection of microfilaraemia in dogs. Undiluted whole blood samples taken from 70 Dirofilaria immitis antigen-positive dogs and 10 serially diluted microfilaraemic blood samples at concentrations of 400, 200, 100, 50, 25 and 12 microfilariae (mff) ml−1 were examined. For filarial speciation, the buffy coat of QBC tubes was mixed with one drop of methylene blue–formalin solution and examined as a direct smear. In 52/70 microfilaraemic blood samples, the number of mff ranged from 12 to 321987 ml−1 (median: 3199 ml−1). The diagnostic sensitivity of the Knott's test, QBC tube method and DBS in undiluted blood samples attained the 100%, 98% and 92.3% levels, respectively. Eighteen dogs tested amicrofilaraemic by all three methods. At concentrations of 400 mff ml−1, a 100% sensitivity was found by all three methods, while at 200 mff ml−1 the Knott's test, QBC tube and DBS were 100%, 100% and 90% sensitive, respectively. The relevant figures at 100 mff ml−1 were 100%, 100% and 80%, at 50 mff ml−1 100%, 100% and 50%, at 25 mff ml−1 100%, 100% and 10% and at 12 mff ml−1 80%, 50% and 10%. At 50 and 25 mff ml−1, the DBS was less sensitive compared to the other two methods, while at 12 mff ml−1, only to the Knott's test. A significant correlation was found between the QBC tube method and Knott's test regarding mff speciation. Therefore, the QBC method may be considered a reliable alternative to the Knott's test for both the detection and speciation of mff in the dog.

A sample of 101 specimens of the unisexual whiptail lizard Cnemidophorus nativo (Squamata; Teiidae) from a coastal site in Bahia State, Brazil were examined for the presence of endoparasites. Of these, 35 (34.7%) harboured helminths. Six helminth species were recovered from C. nativo, including five nematodes (Physaloptera retusa, Physalopteroides venancioi, Subulura lacertilia, Skrjabinelazia intermedia and Parapharyngodon sp., and one cestode (Oochoristica ameivae), all representing new host records. Most lizards were infected by a single species of helminth and none by more than three. Infection rates were neither significantly influenced by host body size nor by environmental factors. The results are compared with data from studies on other whiptail species in both South and North America.

Schistosoma japonicum and S. mansoni were tested for reactivity with an anti-inducible nitric oxide (iNOS) antibody and the distribution of iNOS was studied by immunofluorescent tests in different stages of the parasites. Reactivity was associated with the tegument in both larval schistosomes (sporocysts and cercariae) and eggs. With adult worms, the majority of the immunofluorescence was predominantly subtegumental in S. japonicum and parenchymal in S. mansoni. Fluorescence was also observed in host tissues (snails and mouse liver). In Western blots, the enzyme of S. japonicum had an apparent molecular weight of about 210 kDa. The possible role of worm and host iNOS in the parasite–host interrelation remains to be clarified.

Between October 1999 and October 2001, a total of 510 European eels Anguilla anguilla were captured in 13 different samples from the rivers Thames (five locations) and Test (one location) in southern England. The relationship between parasite component community species richness (CCR) and maximum infracommunity species richness (ICRmax) compared with that previously observed in bird and mammal hosts. Specifically, the maximum number of parasite species occurring in infracommunities equalled or exceeded half the number of parasite species in the component community at that time, across a wide range of CCR values (2–9 parasite species). Furthermore, the frequency distribution of infracommunity richness (ICR) suggested that the species composition of infracommunities is probably random. These findings suggest that intestinal macroparasite infracommunities in eels are unsaturated and potentially species rich assemblages and, in these respects, share a fundamental similarity with the infracommunities of birds and mammals.

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.

The effect of cadmium exposure of the snail first intermediate host Lymnaea peregra on the incidence of encystment of Echinoparyphium recurvatum (Digenea: Echinostomatidae) cercariae without emergence from the snail was investigated. Exposure to 100 μg l−1 Cd for 72 h caused a significant increase in the incidence of first host encystment when compared to controls. In addition, autometallographic staining of E. recurvatum daughter rediae and developing cercariae showed that there was metal accumulation within their body tissues. The significance of these findings to parasite transmission in metal-polluted environments is discussed.

Utilization of a single-species molluscan community of Lymnaea peregra by metacercariae of Echinoparyphium recurvatum over a summer (July–September) period in south-east England showed an increase in the mean number of cysts per host with host size and time of exposure. Aggregation resulting from host and habitat-related factors increased with host size and time of exposure. Encystment within the host was restricted to the peripheral organs in smaller juvenile snails but as snails increased in size, metacercariae were distributed throughout the tissues.

The negative binomial distribution model is reformulated and used to demarcate a host population at a specific level of infection by defining an attribute spanning a range of parasite aggregations. The upper limit of the range specifies the boundary for the classification of the host population and provides a technique to determine the cumulative probability at any level of parasite infection to a high degree of accuracy. This approach also leads to the evaluation of the k parameter, i.e. an inverse measure of dispersion of parasite aggregation, for each fraction of the host population with a discrete level of infection. The basic mathematical premise of the negative binomial function is unaltered in developing this reformulation which was applied to data on the distribution of the trichostrongylid nematode Heligmosomoides polygyrus in populations of the field mouse, Apodemus sylvaticus.

A total of 435 freshly dropped faecal samples were collected from 11 randomly selected ostrich farms during September and November 2002 to determine the prevalence of Libyostrongylus douglassii (ostrich wireworm) in the highveld region of Zimbabwe. Samples, which consisted of 339 samples from breeder birds and 96 samples from pre-slaughter grower birds were screened for nematode eggs using the modified McMaster technique before being individually cultured in an incubator at 28°C. Cultures were examined for the presence of L. douglassii third stage larvae (L3). Using faecal egg counts, eight of 11 farms (72.7%) were positive for L. douglassii in breeders but no eggs were detected in the growers. The faecal culture method detected wireworm larvae in the breeding stock of all farms that were surveyed (100%) and five of the eight farms (62.5%) which had grower birds. Libyostrongylus douglassii was detected in all farms (100%) based on the faecal culture method. Libyostrongylus douglassii was detected for the first time in 7 of 11 farms (64%) surveyed. Data from questionnaires designed to assess farm management practices showed that four out of seven (57.1%) of the ostrich producers were unaware of the importance of wireworms in ostriches. The farms did not have a regular deworming programme for their birds and no faecal samples were sent routinely to the veterinary laboratory for screening of wireworms. Wireworm infections were not taken into consideration by farmers during buying and selling of birds.

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.

The ultrastructure of the flame cells, capillaries, collecting tubes, excretory bladder, excretory atrium, caudal vesicle, lateral caudal ducts and excretory pores of cercariae of Bucephaloides gracilescens (Rudolphi, 1819) Hopkins, 1954 and Prosorhynchus squamatus Odhner, 1905 (Digenea: Bucephalidae) is described. Both species are essentially similar except for some details. The terminal parts of the protonephridia have all the structural features that are typical of trematodes. The collecting tubes in the cercarial body are composed of cells that are wrapped around the lumen. The main collecting tubes are joined to the excretory bladder syncytium by septate junctions. Features of P. squamatus excretory bladder epithelium indicate that it is involved in secretory activity, but this is not the case in B. gracilescens. In both species the luminal surface of the excretory bladder epithelium is increased by lamellae, and the basal plasma membrane forms invaginations. In the bladder syncytium of P. squamatus both apical lamellae and basal invaginations are more developed and mitochondria are also more numerous. The excretory atrium is lined by a syncytium with nucleated cytons located in the surrounding parenchyma. The atrium lining is not continuous with the body tegument and possesses specific secretory inclusions and a thick glycocalyx. Septate junctions connect the atrium syncytium to the excretory bladder epithelium at its anterior end and to the syncytial excretory epithelium lining the caudal vesicle and the lateral caudal ducts at its posterior. In the excretory pores the caudal duct syncytium is joined to the tegument by septate desmosomes.

The development of the monogenean Diplozoon (Nordmann, 1832) (Diplozoidae) necessitates fusion of two larval stages (diporpae) into one double organism. How diporpae find, distinguish and contact each other is unclear, nor is the nature of the stimuli responsible for the dedifferentiation of cells and the formation of new tissues at the site of somatic fusion. Previous studies have implied a role for carbohydrates and glycoproteins in the interactions between helminth parasites and their hosts. Hypothetically, glycoconjugates may also be involved in the establishment of parasite–parasite associations. Changes in the surface saccharide residues during the development of Eudiplozoon nipponicum, a gill ectoparasite of carp (Cyprinus carpio) are described. Flat-fixed specimens and sections of diporpae, juveniles (just-fused) and adult worms were examined following exposure to a panel of 12 FITC-conjugated lectins. All developmental stages exhibited a specific surface binding pattern with ten lectins, indicating that Man/Glc, GlcNAc, Gal and GalNAc are probably present on their surfaces. No reaction was observed with Fuc-specific lectins (UEA-I and LTA). There is evidence that parasite development is accompanied by both qualitative and quantitative changes in the saccharide pattern distribution. The diporpa sucker reacted with nine lectins, excluding BS-II. A very strong binding of PNA, LCA and ConA (Gal and Man/Glc-specific lectins) was observed with the papilla glands of juvenile worms. The role of glandular secretions in this unique fusion process is discussed.

Urine samples were assayed for urinary schistosomiasis in four local government areas (LGA) of Imo State, Nigeria between May 1998 and September 2000. A total of 3504 persons were sampled, with 880 (25.1%) being positive for urinary schistosomiasis, based on records of eggs of Schistosoma haematobium. The prevalence of S. haematobium infection differed in the various LGAs, with Oguta (38.9%) and Owerri-West (10.4%) showing the highest and the lowest values, respectively. Prevalence was higher in males (67.4%) than in females (32.6%) and in subjects 11–20 years of age (31.5%), while prevalence varied among different occupational groups, with farmers ranking the highest (41.6%). Visible haematuria was the predominant symptom (P<0.05). Of 880 persons positive for eggs of S. haematobium, 452 (51.4%) had visible haematuria, followed by suprapubic pains 214 (24.3%) and painful micturition 97 (11.0%). Although 367 (10. 5%) of the sampled subjects with eggs of S. haematobium showed no visible haematuria, 513 (14.6%) clearly demonstrated haematuria.

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.

Anisakis simplex crude extracts (CE) (IPI, ASAC and ALK-ABELLÓ), A. simplex larval antigens purified using a column of IgG anti-A. simplex (PAK) or a column of IgG anti-Ascaris suum (PAS), antigen eluted from columns of IgG anti-A. suum (EAS) and an A. suum adult CE were assayed by the skin prick test. Thirty percent of assayed patients showed a negative reaction in the Anisakis skin prick test. Of 70% positives, two patients had a weal greater than that produced by histamine with the A. simplex extract from ABELLÓ and IPI. The A. suum skin prick test was positive in 35% of patients, with a lower reaction than that observed with the A. simplex extract from IPI in 57% of the sera and a higher reaction in 28% of the sera. All patients with positive reactions with the crude extract also showed positive weals with the two purified antigens, PAK and PAS. All patients, except three, with a reaction to A. suum antigen, were positive to the EAS antigen. In five patients the weal size produced by PAS was greater than that observed with PAK, whereas in another six patients the contrary was observed. Only one of these six patients did not react to EAS antigen, coincident with the patient showing only a slight increase (7%) in the weal size induced by PAK vs. PAS. When the EAS antigen was tested on patients positive to both PAK and PAS, six patients presented a weal size of >30% and only three patients who were positive to PAS did not react to the EAS antigen. These three patients were also negative against the A. suum CE. Purification by affinity chromatography eliminates from the PAS antigen the proteins responsible for producing cross-reactions with Ascaris (present in the EAS antigen).