Macroparasites are generally aggregated within their hosts with infection and aggregation levels resulting from a continuous arms race between maintaining high mating probability and host mortality low for which host and environmentally related factors contribute to some extent. Here, infection and aggregation patterns of the macroendoparasites infecting the flatfish Citharus linguatula, Arnoglossus laterna, Lepidorhombus boscii, Scophthalmus rhombus and Platichthys flesus in 3 areas along the Portuguese coast were analysed. Of the 21 macroendoparasite species found only 1 infected all hosts and most were host or area exclusive. For each host-parasite system, values of the indices varied between areas and macroendoparasites were not always aggregated; in fact, some macroendoparasites were generally uniformly distributed, which can be related to specific density-dependent regulation mechanisms. No general pattern was found for infection or aggregation levels of the 3 species infecting more than 2 hosts along the Portuguese coast, i.e. Lecithochirium rufoviride, Nybelinia lingualis and Anisakis simplex s.l., suggesting that regulation mechanisms are not species specific but are locally determined, with host ecology playing a significant role.

A study has been carried out to investigate whether the action of triclabendazole (TCBZ) against Fasciola hepatica is altered by inhibition of drug metabolism. The cytochrome P450 (CYP P450) system was inhibited using piperonyl butoxide (PB). The Oberon TCBZ-resistant and Cullompton TCBZ-susceptible isolates were used for these experiments. The CYP P450 system was inhibited by a 2 h pre-incubation in PB (100 μm). Flukes were then incubated for a further 22 h in NCTC medium containing either PB; PB+nicotinamide adenine dinucleotide phosphate (NADPH) (1 nm); PB+NADPH+TCBZ (15 μg/ml); or PB+NADPH+TCBZ.SO (15 μg/ml). Morphological changes resulting from drug treatment and following metabolic inhibition were assessed using scanning electron microscopy. After treatment with either TCBZ or TCBZ.SO alone, there was greater disruption to the TCBZ-susceptible than the resistant isolate. However, co-incubation with PB and TCBZ/TCBZ.SO lead to more severe surface changes to the TCBZ-resistant Oberon isolate than with each drug on its own. With the TCBZ-susceptible Cullompton isolate, there was limited potentiation of drug action, and only with TCBZ.SO. The results support the concept of altered drug metabolism in TCBZ-resistant flukes and this process may play a role in the development of drug resistance.

Praziquantel is widely used for the treatment of human schistosomiasis. However, in recent years, there has been increasing concern about the resistance of Schistosoma species to praziquantel. The study described here was designed to evaluate the current susceptibility to praziquantel in S. japonicum in China. During the non-transmission period of schistosomiasis, a random sample of 4760 subjects from the main endemic foci of China were examined using parasitological stool examination. In total, 584 subjects were identified as being infected with S. japonicum, with a prevalence rate of 12 27%. Among them, 565 stool-egg-positive subjects were treated with praziquantel in a single oral dose of 40 mg/kg. Six weeks post-treatment, among the 505 villagers re-examined, 480 (95 05%) had no detectable S. japonicum eggs. Twenty-one subjects still excreting eggs after the first treatment were treated with praziquantel for the second time. All stool samples, including those from those participants with second treatment were re-examined 6 weeks after the second treatment, and no stool-egg-positives were found. The results indicate that the current efficacy of praziquantel against S. japonicum is still high and has not changed after more than 2 decades of repeated, expanded chemotherapy in the main endemic areas of China. It is suggested that no evidence of tolerance or resistance to praziquantel in S. japonicum was detected in China.

Objective. This paper assessed the potential of traditional Chinese medicine (TCM) preparations for using as environmentally acceptable and alternative commercial acaricides. Methods. 22 kinds of TCM, which contained abundant essential oils and showed insecticidal effects, were collected. Samples extracted with petroleum ether, ethyl acetate and methanol were tested against house dust mites Dermatophagoides farinae and their toxicity assessed. Results. The results showed that 3 TCM of Cinnamonum cassia, Eugenia caryophyllata and Pogostemon cablin have higher activity, and the parallel tests showed that the petroleum ether extract had higher activities (0·0046 mg/cm2, 0·005 mg/cm2 and 0·006 mg/cm2 respectively, 24 h, LD50) than the extracts of ethyl acetate and methanol. The acaricidal activity of the ethyl acetate extracts from C. cassia, P. cablin and Asarum sieboldii (0·00144 mg/cm2, 0·00347 mg/cm2 and 0·05521 mg/cm2 respectively, 24 h, LD50) were almost comparable to that of benzyl benzoate and dibutyl phthalate. However, the methanolic extracts of were less effective. Conclusions. This study shows the use of extracts with petroleum ether of C. cassia, P. cablin and E. caryophyllata as eco-friendly biodegradable agents for the control of the house dust mite.

The aim of this study was to determine whether foxes might act as definitive hosts of Sarcocystis alces in moose. In 2 experiments, 6 silver foxes (Vulpes vulpes) and 6 blue foxes (Vulpes lagopus) were fed muscle tissue from moose containing numerous sarcocysts of S. alces, and euthanased 7–28 days post-infection (p.i.). Intestinal mucosal scrapings and faecal samples were screened microscopically for Sarcocystis oocysts/sporocysts, which were identified to species by means of species-specific primers and sequence analysis targeting the ssu rRNA gene. All foxes in both experiments became infected with Sarcocystis; the oocysts were fully sporulated by 14 days p.i., containing sporocysts measuring 14–15×10 μm. Molecular identification revealed that the oocysts/sporocysts belonged to 2 species, S. alces and Sarcocystis hjorti, although sarcocysts of S. hjorti were only identified in moose subsequent to the infection of foxes. In the first experiment, all 8 foxes also became infected with a Hammondia sp. derived from moose, shedding unsporulated, subspherical oocysts, measuring 10–12 μm in diameter, from 6–7 days p.i. onwards. The study proved that canids (the red fox and arctic fox) are definitive hosts for S. alces and S. hjorti, as had been inferred from the phylogenetic position of these species.

The biological membranes of Trypanosoma brucei contain a complex array of phospholipids that are synthesized de novo from precursors obtained either directly from the host, or as catabolised endocytosed lipids. This paper describes the use of nanoflow electrospray tandem mass spectrometry and high resolution mass spectrometry in both positive and negative ion modes, allowing the identification of ~500 individual molecular phospholipids species from total lipid extracts of cultured bloodstream and procyclic form T. brucei. Various molecular species of all of the major subclasses of glycerophospholipids were identified including phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol as well as phosphatidic acid, phosphatidylglycerol and cardolipin, and the sphingolipids sphingomyelin, inositol phosphoceramide and ethanolamine phosphoceramide. The lipidomic data obtained in this study will aid future biochemical phenotyping of either genetically or chemically manipulated commonly used bloodstream and procyclic strains of Trypanosoma brucei. Hopefully this will allow a greater understanding of the bizarre world of lipids in this important human pathogen.

The sheep ked has been largely eradicated in the UK but persists in the feral Soay sheep of St Kilda in the Outer Hebrides. Sheep keds transmit Trypanosoma melophagium, but parasitaemias are typically cryptic and this trypanosome has not been recorded in the St Kilda sheep. Trypanosomes were detected by PCR in preserved keds and were also found in gut smears from live keds; one infected gut was used to establish the trypanosome in vitro. Examination of the morphology of bloodstream forms from culture confirmed its identity as T. melophagium. Most keds were found to harbour the trypanosome, particularly those collected from lambs. DNA was extracted from preserved keds and from trypanosomes grown in vitro. Sequence analysis of the small subunit ribosomal RNA (SSU rRNA) gene and the spliced leader transcript showed the T. melophagium sequences to be very similar to those from T. theileri. A partial sequence of the ked SSU rRNA gene was also obtained. The close genetic relationship of T. melophagium and T. theileri suggests that T. melophagium represents a lineage of T. theileri that adapted to transmission by sheep keds and hence became a specific parasite of sheep.

Objective. Maternal infection has been considered to be a risk factor for filarial infection in offspring. In order to examine the influence of maternal infection in neonates, we have determined the prevalence of circulating filarial antigen (CFA) and anti-filarial antibodies in 119 maternal and corresponding cord blood samples collected from an area endemic for bancroftian filariasis. Method. Prevalence of antigenaemia was detected using Og4C3 circulating filarial antigen enzyme-linked immunosorbent assay. The presence of microfilariae was determined by filtration of a 1 ml sample through a Nuclepore membrane. Antibody isotypes (IgG, IgM, and IgE) to filarial antigen (Setaria digitata antigenic extract) were determined by enzyme linked immunosorbent assay (ELISA). Results. Microfilariae were detected in 14 cases (11·8%), whereas the Og4C3 assay could detect filarial antigen in 44·5% of pregnant mothers. Interestingly, 24·5% of samples born from CFA-positive mothers were found positive for CFA. None of the cord samples from CFA-negative mothers were found positive for CFA. No significant difference was observed in prevalence of filarial-specific IgG, IgM and IgE antibodies in CFA-positive and negative mothers. IgG antibody was detected in 60·5% of maternal and 21·8% of cord samples. IgG antibody in the cord does not differ with the antigen status of the mother. In contrast IgM and IgE antibody prevalence was significantly higher in cord from infected mothers than non-infected mothers (11·3% vs 0 for IgM, 24·5% vs 3·03% for IgE). Conclusion. Our study demonstrates the transplacental transfer of circulating filarial antigen from mother to cord. Filaria-specific IgM and IgE antibodies were higher in cord blood from infected mothers than from non-infected mothers. The findings of the study provide additional circumstantial evidence for pre-natal sensitization to filarial antigens developed in utero.

Concentrations of the elements As, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sn, V, Zn were analysed by inductively coupled plasma mass spectrometry (ICP-MS) in the acanthocephalan Pomphorhynchus laevis and its fish host Barbus barbus. A total of 27 barbels were collected from the Danube River in autumn 2006 close to the town Kozloduy (685 river kilometer) on the Bulgarian river bank. Fish were divided into 3 groups. According to their P. laevis infrapopulation size hosts were considered as heavily infected (>100 worms per fish) and lightly infected (<20 worms per fish). The third group was used to compare heavy metal concentrations between male and female P. laevis. The 5 elements As, Cd, Cu, Pb and Zn were detected in significantly higher concentrations in parasites compared to host tissues (muscle, intestine, liver). According to the calculated mean bioconcentration factors, 3 more elements (Co, Mn, V) showed usually higher concentrations in P. laevis. Comparisons between heavily and lightly infected fish revealed significant differences only for V with higher concentrations for the heavily infected group. Concerning sex-specific metal accumulation V and Zn showed significant differences (V, at P<0·05; Zn, at P=0·05), with higher levels of both metals in females of P. laevis. Our results suggest that – for the metals analysed – the size of the parasite infrapopulation plays no role in the degree of metal accumulation. Similarly, parasite sex seems not to be a crucial factor for metal accumulation in the parasites. Thus, for metal monitoring purposes there is no need to take these aspects into account, which makes the use of parasites as bioindicators more applicable.

The review addresses how infection with Trypanosoma brucei affects the development, survival and functions of B lymphocytes in mice. It discusses (1) the contributions of antibodies to trypanosome clearance from the bloodstream, (2) how B lymphocytes, the precursors of antibody producing plasma cells, interact with membrane form variable surface glycoprotein (VSG), i.e. with monovalent antigen that is free to diffuse within the lipid bilayer of the trypanosome plasma membrane and consequently can cross-link B cell antigen specific receptors by indirect processes only and (3) the extent and underlying causes of dysregulation of humoral immune responses in infected mice, focusing on the impact of wild type and GPI-PLC−/− trypanosomes on bone marrow and extramedullary B lymphopoiesis, B cell maturation and survival.

Diagnosis of loiasis and analysis of the specific immune response are limited by a paucity of parasite material. To circumvent this problem, a Loa loa antigen has been expressed in a prokaryote vector (pTrcHis). Immunization of Balb/c mice with this soluble recombinant protein produced a strong antibody response, with antibodies recognizing 2 major bands of 38 and 20 kDa in a native crude extract of Loa loa adult worms and microfilariae on Western blots. The target molecule was located mainly in the hypodermis and cuticle of the adult worm. Analysis of human IgG subclasses against this antigen by enzyme-linked immunosorbent assay (ELISA) showed IgG1, IgG2 and IgG3 but not IgG4 reactivity. IgG2 against this recombinant antigen was 100% specific for loiasis when tested against samples from European donor individuals. The same IgG2 antibodies showed 91% specificity for loiasis by comparison with Wuchereria bancrofti, Onchocerca volvulus, Mansonnella perstans and other helminth infections. Furthermore, the IgG2 antibody level correlated with the density of Loa loa microfilariae (r=0·400; P=0·02). This recombinant 15r3 molecule and specific IgG2 assay may be useful for monitoring control programmes.

Plerocercoids of the pseudophyllidean cestode Schistocephalus solidus infect the three-spined stickleback Gasterosteus aculeatus, with important consequences for the biology of host fish. Techniques for culturing the parasite in vitro and generating infective stages that can be used to infect sticklebacks experimentally have been developed, and the system is increasingly used as a laboratory model for investigating aspects of host-parasite interactions. Recent experimental laboratory studies have focused on the immune responses of hosts to infection, the consequences of infection for the growth and reproductive development of host fish and the effects of infection on host behaviour. Here we introduce the host and the parasite, review the major findings of these recent experimental infection studies and identify further aspects of host parasite interactions that might be investigated using the system.

Fatty acid binding proteins are considered to be promising vaccine candidates against trematodiasis. In order to provide additional information about their function in Fasciola gigantica we performed a comparative analysis of FgFABP1 and FgFABP3, two isoforms with quite different isoelectric points of 4·9 and 9·9 and 67% sequence identity. Both are expressed in the juvenile and adult parasite but differ in their tissue-specific distribution. In addition, the sequence of FABP3 is identical in F. hepatica and F. gigantica indicating the protein's functional importance in this genus. Immune sera produced against soluble recombinant FgFABPs reacted with 14 kDa antigens in crude worm, soluble egg, cirrus sac extracts, and excretion/secretion product. Both FgFABPs were located in the parenchyma of the parasite but in addition, FgFABP1 was abundant in testes and spermatozoa while FgFABP3 was abundant in vitelline cells, eggs, and caecal epithelium. Mass spectrometry identified FgFABP1 and FgFABP3 in the ES product whereas only FgFABP3 was identified in egg extract. Serum samples of an experimentally infected rabbit reacted from week 6 post-infection with FgFABP3 and from week 12 with FgFABP1 while sera of infected sheep were not reactive. The results suggest differences in the biological functions of these 2 isoforms and differences in the host/parasite interaction that should be considered for their potential as vaccines against fascioliasis.

Previous studies have shown that host immunity regulates the fecundity of nematodes. The present study was aimed at clarifying the reversible nature of fecundity in response to changes of immunological status and to determine which effector cells are responsible for compromising fecundity in Heligmosomoides polygyrus. Enhanced fecundity was observed in immunocompromised SCID and nu/nu mice compared to those in the corresponding wild-type mice, with significantly fewer numbers of intrauterine eggs produced in the wild-type than in the immunodeficient mice. When 14-day-old adult worms from BALB/c mice were transplanted into naïve BALB/c mice, their fecundity increased significantly as early as 24 h post-transplantation, but not when they were transferred into immune mice, suggesting the plastic and reversible nature of fecundity in response to changes in host immunological status. In mast cell-deficient W/Wv mice, nematode fecundity was significantly higher than in mast cell-reconstituted W/Wv or +/+ mice. The serum levels of the mast-cell protease mMCP1 were markedly increased in the wild-type as well as the mast cell-reconstituted W/Wv, but not in the W/Wv, SCID, or nu/nu mice during infection. These findings raise the interesting possibility that certain activities of mast cells, either directly or indirectly, regulate parasite fecundity during infection.

An analysis of the metrics of Schistocephalus solidus infection of the threespine stickleback, Gasterosteus aculeatus, in Walby Lake, Alaska, showed that an epizootic ended between 1996 and 1998 and another occurred between 1998 and 2003. The end of the first epizootic was associated with a crash in population size of the stickleback, which serves as the second intermediate host. The likely cause of the end of that epizootic is mass mortality of host fish over winter in 1996–1997. The deleterious impact of the parasite on host reproduction and increased host predation associated with parasitic manipulation of host behaviour and morphology to facilitate transmission might also have played a role, along with unknown environmental factors acting on heavily infected fish or fish in poor condition. The second epizootic was linked to relatively high levels of prevalence and mean intensity of infection, but parasite:host mass ratios were quite low at the peak and there were no apparent mass deaths of the host. A number of abiotic and biotic factors are likely to interact to contribute to the occurrence of epizootics in S. solidus, which appear to be unstable and variable. Epizootics appear to depend on particular and, at times, rare sets of circumstances.

Recently, a way was opened with the development of many mathematical methods to model and analyze genome-scale metabolic networks. Among them, methods based on graph models enable to us quickly perform large-scale analyses on large metabolic networks. However, it could be difficult for parasitologists to select the graph model and methods adapted to their biological questions. In this review, after briefly addressing the problem of the metabolic network reconstruction, we propose an overview of the graph-based approaches used in whole metabolic network analyses. Applications highlight the usefulness of this kind of approach in the field of parasitology, especially by suggesting metabolic targets for new drugs. Their development still represents a major challenge to fight against the numerous diseases caused by parasites.

There is a pressing need to develop novel anti-schistosomal drugs, as current treatment relies largely on praziquantel (PZQ). To further strengthen current evidence of the anti-schistosomal properties of mefloquine (MQ), we studied the temporal effect of this compound in vitro and in vivo, and examined alterations on the tegumental surface of schistosomula and adults of S. mansoni by means of scanning electron microscopy (SEM). Schistosomula and adults were each incubated in vitro using MQ over a wide concentration range (1–100 μg/ml). In addition, mice infected with adult S. mansoni were treated with a single oral dose of 400 mg/kg MQ, and worms were recovered 24, 48, 72, 96 and 120 h following treatment. MQ showed a rapid onset of action on schistosomula in vitro; 100 and 75 μg/ml of MQ killed schistosomula immediately; the minimal lethal and effective concentrations of MQ on schistosomula after 1 h were 25 and 5 μg/ml, respectively. Adult worms incubated with 100 and 10 μg/ml of MQ were dead after 1 h and 24 h of incubation, respectively. A hepatic shift of adult schistosomes was observed in mice already 24 h after treatment, and 120 h following treatment >98% of all worms had translocated to the liver. SEM observations revealed extensive tegumental destruction, including blebbing, shrinking and sloughing, particularly following in vitro incubation and on the tegument of female worms.

IgA and IgE activity against Teladorsagia circumcincta was investigated in a flock of Texel lambs following natural, mixed nematode infection among lambs. The distribution of IgA activity was similar to a gamma distribution whereas IgE activity was different. Box-Cox analysis demonstrated that X0·25 was a suitable transformation to normalise IgE responses. The transformed IgE activity was under moderate to strong genetic control. Nine different allergens were identified by proteomic analysis. Tropomyosin was selected for further analysis. IgE activity against tropomyosin was moderately heritable and associated with decreased egg counts and with reduced body weight at the time of sampling.

Although there is a growing recognition that the transfer of diseases between humans and non-human primates can be of great significance for conservation biology, there have been only a few studies focusing on parasites. In this study, saddleback (Saguinus fuscicollis) and moustached tamarin (Saguinus mystax) from the rainforest of the Peruvian lowlands were used as models to determine helminth parasite associations between canopy-dwelling primate species and a nearby human settlement. The human population showed high prevalences of infestation with a number of nematodes, including Ascaris lumbricoides (88·9%), Trichuris trichiura (37%) and hookworms (55·6%). However, the ova of these geohelminths were not detectable in tamarin faeces. Thus, no direct parasite transfer from humans to non-human primates could be documented. However, tamarin groups with more frequent contact to humans and their facilities had significantly higher prevalences and egg output of Prosthenorchis elegans, an important primate pathogen, than a forest group. In contrast, a cestode was significantly more common with more egg output in sylvatic than in human-associated groups. Human alteration of the habitat is likely to play a major role in determining the occurrence, prevalence and intensity of helminth infestation of wild non-human primates.

Figs and their pollinating wasps are a classic example of an obligate mutualism. In addition, figs are parasitized by a suite of non-mutualistic wasps whose basic ecology is largely undescribed. Sycophilomorpha (subfamily Epichrysomallinae) fig wasps are ovule gallers and the genus contains only 1 described species. An undescribed Sycophilomorpha species parasitized Ficus altissima at Xishuangbana, Southwestern China. The wasp was observed ovipositing on the tiny immature figs that were still concealed beneath the involucral bracts. A Sycophilomorpha wasp oviposited on more than 1 fig and spent long time-periods to lay large clutches on a single fig. The wasps naturally occurred on all 7 sampled trees, but the occurrence of wasps was significantly different among trees, crops and months. These wasps were able to prevent unpollinated figs from being aborted, and their offspring were able to develop in the figs that otherwise had no pollinator wasps or seeds. The Sycophilomorpha wasp had a detrimental effect on the fig–fig wasp mutualism. Figs in which Sycophilomorpha wasps were present, produced significantly fewer seeds, pollinators and cheaters. However, the abundance of Sycophilomorpha in a fig was only significantly negatively correlated with pollinator production and not seed or cheater production. Our study illustrates a previously unknown fig wasp niche and expands our understanding of factors that can affect the fig–fig wasp interaction.