Host manipulation by trophically transmitted parasites may predispose infected hosts to predation and in this way enhance parasite transmission. In most study systems, however, the evidence comes from laboratory studies, and therefore knowledge of the effect of manipulation on parasite transmission efficiency in the wild is still limited. Here we examined the effect of Diplostomum spathaceum (Trematoda) eye flukes on the susceptibility of fish intermediate hosts to predation by bird definitive hosts. Our earlier studies have shown that the parasite alters fish phenotype and increases their susceptibility to artificial predation under laboratory conditions. In the present field study, we allowed wild birds to feed on fish from cages placed into a lake, and found that predation vulnerability of infected fish did not differ from that of controls. However, we suggest that the experimental set-up likely affected the result because the cages allowed gulls, which caught most of the fish in the study, to feed on fish in an easy, unnatural manner by standing on the edges of the cages. Nevertheless, considerable predation was observed, which provides important initial evidence of how this question should be addressed in the wild.

Human Oesophagostomum infections are locally common in northern Ghana. The present study describes the results of a cross-sectional survey involving 1011 subjects, selected by a compound-based random sampling method from 1227 compounds in 24 villages. Selected persons were examined by both Kato and coproculture methods. Hookworm-like eggs, representing ova of Oesophagostomum bifurcum and hookworm were detected in 87·5% of the Kato smears. The geometric mean egg count of the infected subjects was 1018. Upon coproculture, third-stage larvae of O. bifurcum and hookworm were detected in 53·0% and 86·9% of subjects respectively. Oesophagostomum infections were clustered but no clear explanation for aggregation of infections could be found as yet. Subjects infected with hookworm had a 5-fold higher risk of being infected with O. bifurcum. Infection rates in adult women were higher than in adult men. No association was found with family size, level of hygiene or with the presence of animals in the compounds. Representatives of the Bimoba-tribe were significantly more infected than those of the other tribes. It appears, however, that this tribal association is a geographical phenomenon: Bimoba are mostly living in villages with the highest infection rates.

The nodule worm Oesophagostomum bifurcum (Nematoda: Strongylida) is a parasite of major human health importance predominantly in northern Togo and Ghana. Currently, it is estimated that 0·25 million people are infected with this nematode, and at least 1 million people are at risk of infection. Infection with this parasite causes significant disease as a consequence of encysted larvae in the wall of the large intestine. In spite of the health problems caused by O. bifurcum, there have been significant gaps in the knowledge of the biology, transmission and population genetics of the parasite. This review provides an account of some recent insights into the epidemiology and genetics of the parasite from human and non-human primate hosts in specific regions of Africa using molecular tools. Recent research findings are discussed mainly in relation to non-human primates being reservoirs of infection, and the consequences for the prevention and control of oesophagostomiasis in humans are briefly discussed.

As part of studies on the nature of the endemic virus infections in natural rodent hosts, the possible association of cyst forms of Pneumocystis spp. with the presence of hanta-, cowpox-, and arenavirus antibodies in wild mice (Apodemus flavicollis, N=105; Apodemus agrarius, N=63; Micromys minutus, N=50) and the common shrew (Sorex araneus, N=101) was studied in south-central Finland. One hantavirus (Saaremaa virus, SAAV) seropositive A. agrarius, and 2 cowpoxvirus (CPXV) seropositive S. araneus were detected, and antibodies against an arenavirus (Lymphocytic choriomeningitis virus, LCMV) were found in all 3 mouse species but not in shrews. Cyst forms of Pneumocystis spp. were detected in all species except A. agrarius. There was no significant association between virus antibodies (LCMV in mice, and CPXV in shrews) and cyst forms of Pneumocystis in any of the species. Concurrent presence of virus antibodies (LCMV) and cyst forms of Pneumocystis were detected only in 1 M. minutus. In conclusion, we found no evidence of any association between Pneumocystis and antibodies to any of the viruses tested.

The ZAP Express cDNA library was constructed using mRNA extracted from the triactinomyxon spores of Myxobolus cerebralis. First-strand cDNA was synthesized using Moloney Murine leukaemia virus reverse transcriptase. Following second-strand cDNA synthesis, the double-stranded cDNA was digested with Xho I restriction enzyme, cDNA fragments less than 400 bp were removed and the remaining cDNA was ligated with the lambda ZAP Express vector. The recombinants were packaged in vitro using Gigapack III gold packaging extract. The primary cDNA library titre contained 0·5×106 clones, with 97% recombinant and only 3% non-recombinant clones. The cDNA library was then screened using the anti-triactinomyxon antibodies. Positive clones were selected and re-screened twice more to give a final selection of 526 clones. One clone (46-5) was selected randomly and subjected to in vivo excision of the pBK-CMV phagemid from the ZAP express vector. The sequence of the entire clone was obtained using rapid amplification of the cDNA ends. A search of the clone sequence against GenBank revealed that it related to ribosomal protein L23 and it had a high percentage similarity to this protein from different species. A conserved domain for ribosomal protein L23 was also identified in the clone sequence.

A microsporidian infection was discovered in laboratory cultures of Drosophila species. Ultrastructural examination suggested it belonged to the poorly characterized species Tubulinosema kingi, and morphological and sequence data are presented. We explored how T. kingi affected the fitness of Drosophila melanogaster and D. subobscura, as well as the fitness of 2 of their parasitoids, Asobara tabida and Pachycrepoideus vindemiae. In Drosophila, infections caused changes in most of the traits we looked at that were associated with fitness, in particular causing a 34–55% reduction in early-life fecundity. Parasitoid fitness was affected more severely by infection than that of their hosts, with pupal mortality in particular increasing by 75–89%. We investigated the most important routes of transmission for T. kingi in a laboratory setting. Letting Drosophila larvae feed on medium contaminated with spores from infected dead flies resulted in 100% infection. Low levels of transmission (<10%) were found between larvae, and vertically between mothers and their offspring. Parasitoids developing in infected hosts all became infected, but infected adults were neither able to transmit the pathogen to their offspring nor to their offspring's Drosophila host, either directly, or via contamination of the ovipositor or other body parts. A field survey of Drosophila and their parasitoids in southern England revealed no natural infections. We discuss the potential importance of Microsporidia in parasitoid-host interactions, and for those working with Drosophila in the laboratory.

Leishmania parasites are able to survive in host macrophages despite the harsh phagolysosomal vacuoles conditions. This could reflect, in part, their capacity to secrete proteins that may play an essential role in the establishment of infection and serve as targets for cellular immune responses. To characterize Leishmania major proteins excreted/secreted early after promastigote entry into the host macrophage, we have generated antibodies against culture supernatants of stationary-phase promastigotes collected 6 h after incubation in conditions that partially reproduce those prevailing in the parasitophorous vacuole. The screening of an L. major cDNA library with these antibodies led us to isolate 33 different cDNA clones that we report here. Sequence analysis revealed that the corresponding proteins could be classified in 3 groups: 9 proteins have been previously described as excreted/secreted in Leishmania and/or other species; 11 correspond to known proteins already characterized in Leishmania and/or other species although it is unknown whether they are excreted/secreted and 13 code for unknown proteins. Interestingly, the latter are transcribed as shown by RT-PCR and some of them are stage regulated. The L. major excreted/secreted proteins may constitute putative virulence factors, vaccine candidates and/or new drug targets.

Tubulin is the predominant phosphoprotein in Trypanosoma cruzi epimastigotes and is phosphorylated by a protein kinase CK2. Interestingly, the presence or absence of divalent cations affected the solubilization of a pool of the parasite tubulin and the CK2 responsible for its phosphorylation. This fraction of tubulin and its kinase co-eluted using phosphocellulose, DEAE-Sepharose and Sephacryl S-300 chromatographies. Anti-α tubulin antibodies co-immunoprecipitated both tubulin and the CK2 responsible for its phosphorylation, and anti-CK2 α-subunit antibodies immunoprecipitated radioactively labelled α and β tubulin from phosphorylated epimastigote homogenates. Additionally, native polyacrylamide gel electrophoresis of the purified and radioactively labelled fraction containing tubulin and its kinase demonstrated the phosphorylation of a unique band that reacted with both anti-CK2 α-subunit and anti-tubulin antibodies. Together, these results establish a strong interaction between a pool of the heterodimeric α/β tubulin and a CK2 in this parasite. Hydrodynamic measurements indicated that the T. cruzi tubulin-CK2 complex is globular with an estimated size of 145·4–147·5 kDa.

The nature of the proteins which comprise the in vitro excretory/secretory products (ES) of the fourth-stage larva (L4) and adult Teladorsagia circumcincta are largely undefined, despite the fact that this nematode induces profound changes, in part related to parasite ES, in the cellular architecture of the glands lining the abomasal surface of infected sheep and goats. In this study, the protein components of L4 and adult ES were fractionated using 1D gel electrophoresis and the major protein bands, detected by Coomassie blue staining, excised from the gel and subjected to tryptic digest and subsequent mass spectrometric analysis. The resultant peptide mass fingerprints were used to identify 15 L4 and 13 adult ES proteins. Several proteins, such as globin and some metabolic enzymes, were present in both ES. L4 ES alone contained thioredoxin peroxidase, an enzyme that can detoxify free radicals resulting from host inflammatory responses to the parasite, a cysteine proteinase which may aid penetration of the gastric mucosa and 2 different galectins which may influence cell differentiation and morphogenesis. Adult ES contained a nucleoside diphosphate kinase homologue, an enzyme which has been linked to cellular changes and can affect liquid secretion and goblet cell degranulation.

The anthelmintic properties of tanniferous plants and of their secondary metabolites represent one possible alternative to chemotherapy that is currently being explored as a means of achieving sustainable control of gastrointestinal nematodes in ruminants. Previous in vivo and in vitro results suggest that tanniferous plants can have direct anti-parasitic effect against different stages of nematodes. However, the mode of action of the bioactive plant compounds remains obscure. The objectives of the current study were (1) to examine the hypothesis that extracts of tanniferous plants might interfere with the exsheathment of third-stage infective larvae (L3); (2) to assess the role of tannins in the process by examining the consequence of adding an inhibitor of tannins (polyethylene glycol: PEG) to extracts. The effects of 4 tanniferous plant extracts on exsheathment have been examined on L3 of Haemonchus contortus and Trichostrongylus colubriformis. Artificial exsheathment was induced in vitro by adding hypochloride solution to larval suspension. The evolution of exsheathment with time was measured by repeated observations at 10-min interval for 60 min. The selected plants were: genista (Sarothamnus scoparius), heather (Erica erigena), pine tree (Pinus sylvestris), and chestnut tree (Castanea sativa), with tannin contents ranging from 1·5 to 24·7% of DM. Extracts of a non-tanniferous plant (rye grass, tannin content: 0·3% of DM) were included in the assay as negative controls. The extracts were tested at the concentration of 600 μg/ml and the effects were compared to the rate of exsheathment of control larvae in PBS. No statistical differences in the pattern of exsheathment was observed after addition of rye grass or genista extracts for both nematode species and with heather extracts for T. colubriformis. In contrast, pine tree extracts on larvae of both species and heather extracts with H. contortus induced a significant delay in exsheathment. Last, contact with chest nut extracts led to a total inhibition of the process for both nematodes. These results suggest that extracts of tanniferous plants might affect a key process in the very early stages of larval invasion of the host. In most cases, the addition of PEG led to a total or partial restoration towards control values. This suggests that tannins are largely involved in the inhibitory process. However, other secondary metabolites may also interfere with the process that would help to explain some of the differences in response observed between the two nematode species.

Several species of opportunistic histophagous scuticociliates have been implicated in systemic infections of farmed fish. In turbot, scuticociliatosis is an emerging disease, and the identification of the parasite species involved is controversial. We have previously isolated Philasterides dicentrarchi from farmed turbot scuticociliatosis outbreaks in northwest Spain. In the present study, we report detailed ultrastructural studies of this parasite, and investigate phylogenetic relations with other members of the order Philasterida on the basis of sequence comparison of the small-subunit rRNA (SSUrRNA) gene. Ultrastructural study indicates the presence of dikinetids in the anterior two-thirds of the body; micronucleus closely associated with the macronucleus, though not physically connected; numerous mitochondria located below the cell cortex, parallel to the surface; numerous spherical and fusiform extrusomes located close to the plasma membrane. We consider that these characteristics are useful for diagnosis of infections by this parasite. A nested 350-bp nucleotide sequence of the SSUrRNA gene of the turbot P. dicentrachi isolate showed high identity with previously reported SSUrRNA gene sequences from 2 scuticociliates isolated from olive flounder Paralichthys olivaceus in Korea, namely P. dicentrarchi (98%) and Miamiensis avidus (99%); conversely, our P. dicentrarchi sequence showed low identity (86%) with that of Uronema marinum, a scuticociliate that has also been implicated in scuticociliatosis outbreaks in turbot in Europe and olive flounder in Asia. Phylogenetic tree construction on the basis of the SSUrRNA gene sequences, using the neighbour-joining method, confirm that the different P. dicentrarchi isolates and M. avidus are closely related and a possible synonymy between both ciliates species should be considered.

Post-mortem examinations of harbour porpoises, Phocoena phocoena, regularly reveal heavy parasitic worm burdens. These same post-mortem records show varying levels of polychlorinated biphenyls (PCBs) accumulating in the blubber of porpoises. Although a number of papers have documented geospatial and temporal changes of PCBs and their detrimental effects on marine mammal health, as yet none have examined their role in determining nematode burdens in wild marine mammal populations. Using a data set consisting of harbour porpoises stranded in the UK between 1989 and 2002, we found a significant, positive association between PCB levels and nematode burdens, although the nature of the relationship was confounded with porpoise sex, age and cause of death. It was also apparent that individuals with the heaviest infestations of nematodes did not have the highest PCB level: while PCBs are important, they are clearly not the sole determinants of nematode burdens in wild populations of the harbour porpoise around the UK.

β–glucans are immunomodulators able to activate innate immunity and to potentiate acquired immune reactions. We investigated the impact of co-administration of liposomized β-glucan on the larvicidal effect of the anthelmintic praziquantel (PZQ) in the livers and peritoneal cavities in mice infected with Mesocestoides vogae (M. corti). Also, within 2 weeks following therapy (up to day 29 p.i.) we examined collagen synthesis in the livers of mice by means of biochemical determination of hydroxyprolin concentration, total mast cell counts and cell proliferative capacity using immunohistochemical and radiometrical methods. After co-administration of liposomized glucan (LG) and PZQ efficacy (%) was significantly higher than after treatment with either compond alone, particularly in the peritoneal cavity compared to the liver. In comparison with the control, more intense collagenesis was found in the B-liver parts (high intensity of infection) and lowering of collagen content in the A-parts (very weak infection). This effect was strongest after LG treatment and co-administration of PZQ abolished the pro-fibrotic effect of LG. In all groups, mast cell counts were higher in the B-liver parts than in the A-parts and the dynamics of mastocytosis was profoundly modulated following therapy. Whereas the effect of PZQ was only moderate, early and very strong onset was seen after LG treatment. Administration of PZQ supressed LG induced-elevation of mast cells counts in both liver parts. Using DNA S-phase markers (BrdU and 3H-thymidine) the proliferative capacity was shown to be associated with several kinds of liver cells. Therapy significantly stimulated [3H]-thymidine incorporation (cell proliferation) only in the A-parts over that in control, the most after LG administration. In summary (i) the anthelmintic effect of PZQ could be enhanced after simultaneous administration of the immunomodulator β-glucan entrapped in a liposomal carrier, (ii) intense mastocytosis seen after treatment with LG seems to have a direct role in the glucan′s pro-fibrotic activity and can be abolished after co-administration of PZQ in a time-dependent manner, (iii) the pattern of cell proliferation indicates that in the case of PZQ treatment, the reparative processes of liver parenchyma are enhanced in an inverse correlation with the intensity of infection.

Infection by the cestode Taenia taeniaeformis was investigated within numerous cyclic populations of the fossorial water vole Arvicola terrestris sampled during 4 years in Franche-Comté (France). The relative influence of different rodent demographic parameters on the presence of this cestode was assessed by considering (1) the demographic phase of the cycle; (2) density at the local geographical scale (<0·1 km2); (3) mean density at a larger scale (>10 km2). The local scale corresponded to the rodent population (intermediate host), while the large scale corresponded to the definitive host population (wild and feral cats). General linear models based on analyses of 1804 voles revealed the importance of local density but also of year, rodent age, season and interactions between year and season and between age and season. Prevalence was significantly higher in low vole densities than during local outbreaks. By contrast, the large geographical scale density and the demographic phase had less influence on infection by the cestode. The potential impacts of the cestode on the fitness of the host were assessed and infection had no effect on the host body mass, litter size or sexual activity of voles.