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The effect of canine intestinal helminths on the haematological profile of 200 dogs, of both sexes and variable age, visiting university veterinary clinics for routine examination was investigated. The dogs were assigned to parasitized (n = 39) and non-parasitized (n = 161) groups of animals. Coprological examination revealed a 19.5% prevalence of different species of the helminths. Of these animals, 10.25% had mixed infections with Ancylostoma caninum, Toxascaris spp. and Dipylidium caninum. The intensity of A. caninum infection was the highest, with mean egg counts of 951.43 (standard error 88.66), followed by Toxascaris 283.33 (standard error 116.81) and D. caninum. The parasitized animals had significantly lower levels of haemoglobin, packed cell volume and total erythrocyte counts than non-parasitized animals (P < 0.01). Values of other parameters, except for lymphocytes and eosinophils, were not different between the two groups. Analyses of the haematological profile revealed normocytic hypochromic anaemia in the parasitized group of animals.

The tapeworm Ligula intestinalis commonly infests roach (Rutilus rutilus) and is responsible for the inhibition of gonad development. In order to better understand the effect of the plerocercoid on fish physiology, and to discriminate parasitization effects from those of endocrine-disrupting compounds (EDC), Cyp19b and Cyp19a aromatase expression was investigated by real-time quantitative polymerase chain reaction (PCR) in brain and gonads of ligulosed roach, caught from a reference site. Data were compared to reproductive and endocrine endpoints previously reported in a larger cohort study (including the sampled population of the present one), such as gonadosomatic index, Fulton index, gonadal histology, plasma sex steroid levels and brain aromatase activity. A decrease in Cyp19b expression in the brain of infected fish was demonstrated, in agreement with the reduction of aromatase activity previously described. In contrast, Cyp19a expression in the gonads appeared to be enhanced in ligulosed fish, in accordance with the presence of immature but differentiated sexual tissues. Together these results show that: (1) L. intestinalis infestation results in an alteration of aromatase expression which, in particular, may have profound effects on the fish brain; and (2) L. intestinalis infection must be considered as a major confounding factor in ecotoxicological studies using aromatase expression as an EDC biomarker. Moreover, the concordance between activity and expression--investigated for the first time in the same population--gives a functional relevance to the transcript aromatase dosage in the brain. Finally, quantitative PCR was confirmed as a sensitive approach, enabling aromatase status to be defined in the poorly developed gonads of ligulosed individuals.

Abstract: The type species of the cestode genus Arostrilepis Mas-Coma et Tenora, 1997, Arostrilepis horrida (Linstow, 1901), is redescribed on the basis of the syntype material from the brown rat.(Rattus norvegicus) deposited in the collection of the Museum fir Naturkunde, Berlin. Arostrilepis horrida (sensu lato), reported from a wide range of rodents throughout the Holarctic Region, is shown to be a species complex. The proposed host range and geographical distribution ofA. horrida (sensu stricto) are limited to the data reported in the original description. The previously proposed synonymy ofA. horrida is examined and the following species are excluded from the list of its synonyms: Hymenolepisprocera Janicki, 1904, H. arvicolina Cholodkowsky, 1913, H. sciurina Cholodkowsky, 1913 and H. mathevossianae Akhumyan, 1946; these are considered species inquirendae. Specimens previously identified as A. horrida from voles from the Asian part of Russia are revised and newly collected materials are worked out. Two new species, A. macrocirrosa sp. n. and A. tenuicirrosa sp. n., are described. The main differentiating characters used to distinguish Arostrilepis spp. are the form and size of cirrus and its armature as well as the type of arrangement for the testes. The new species can also be distinguished from one another on the basis of sequences of the ITS2 rRNA gene. The generic diagnosis of Arostrilepis is emended. Hymenolepis neurotrichi Rausch, 1962, which had been placed in Arostrilepis by Mas-Coma and Tenora (1997), does not correspond to the generic diagnosis and is considered a species incertae sedis.

Successful metazoan parasitism, among many other factors, requires a supply of nutrients and the removal of waste products. There is a prerequisite for a parasite-defined vasculature. The angiogenic mechanism(s) involved presumably depend on the characteristics of the tissue- and vascular system-dwelling, parasitic helminths. Simplistically, 2 possibilities or a combination of both have been considered in this review. The multifactorial induction of parasitic helminth-associated neovascularization could arise through, either a host-, a parasite- or a host-/parasite-dependent, angiogenic switch. Most studies appear to support the first and third hypotheses, but evidence exists for the intrahepatic cestode Echinococcus multilocularis, the free-living nematode Caenorhabditis elegans and the intravascular trematode Schistosoma mansoni for the second inference. In contrast, the nematode anti-coagulant protein NAPc2 from adult Ancylostoma caninum is also an anti-angiogenic factor.

Reproductive parameters of Ligula intestinalis-infected roach (Rutilus rutilus) which were held under long-tem laboratory conditions with unlimited food supply were investigated. Although uninfected and infected roach showed no difference in condition factor and both groups deposited perivisceral fat, the gonadosomatic-index was significantly lower in infected female and male roach. Quantitative histological analysis revealed that gonad development was retarded upon parasitization in both genders. In contrast to the phenotype described in the field, infected females were able to recruit follicles into secondary growth, but a high percentage of secondary growth follicles underwent atresia. In both genders, the histological data corresponded well with reduced expression of pituitary gonadotropins and lowered plasma concentrations of sex steroids, as revealed by real-time RT-PCR and ELISA, respectively. Furthermore, a reduction of vitellogenin mRNA and modulated expression of sex steroid receptors in the liver was demonstrated. Like in the field, there was a significant adverse impact of L. intestinalis on host reproductive physiology which could not be related to parasite burden. Our results show, for the first time, that maintenance under laboratory conditions can not abolish the deleterious effect of L. intestinalis on gametogenesis in roach, and indicate a specific inhibition of host reproduction by endocrine disruption.

From February to October 2007, thirty specimens of the king mackerel, Scomberomorus cavalla (Cuvier, 1829) were purchased from markets in the municipalities of Niterói and Rio de Janeiro. The fishes were measured, filleted and further had their organs investigated for helminths. Ten out of the thirty fish specimens were parasitized with anisakid nematodes represented by Anisakis sp. and Contracaecum sp. with prevalence of 1% and 16%, mean intensity of 2 and 3.31 and mean abundance of 0.02 and 0.53, respectively. The infection range with Contracaecum sp. was 1-9. The sites of infection were the stomach serosa and mesentery. Seventeen fish specimens (53%) out of the 30 investigated were parasitized with Trypanorhyncha metacestodes, identified as Callitetrarhynchus gracilis, Pterobothrium crassicole, Callitetrarhynchus speciosus and Tentacularia coryphaenae in the mesentery, with prevalence of 26, 20, 6, 3%, intensity and mean intensity of 3.25, 3.5, 1, 2 and mean abundance of 0.86, 0.7, 0.06 and 0.06, respectively. The infection range due to C. gracilis and P. crassicole were of 1-5 and 1-20, respectively. Anisakis sp., C. speciosus and P. crassicole are reported in S. cavalla for the first time. Considerations on the zoonotic potential of the parasites and their rules in sanitary inspection are presented., (Copyright © 2010 Elsevier B.V. All rights reserved.)

In the study of parasite-mediated sexual selection, there has been controversial evidence for the prediction that brighter males should have fewer parasites. Most of these studies have focused on one parasite species. Our aim was to investigate the expression of carotenoid-based coloured signals in relation to patterns of multiple parasite infections, to determine whether colour reflects parasite load of all parasite species, or whether different relationships might be found when looking at each parasite species independently. We investigated the relationship between bill colour, body mass and plasma carotenoids and parasite load (feather chewing lice, blood parasite Plasmodium sp., intestinal parasites cestodes and coccidia) in the blackbird (Turdus merula). Bill colour on its own appeared to be a poor predictor of parasite load when investigating its relationships with individual parasite species. Variation in parasite intensities at the community level was summarised using principal component analysis to derive synthetic indexes of relative parasite species abundance and absolute parasite load. The relative abundance of parasite species was strongly related to bill colour, plasma carotenoid levels and body mass: birds with relatively more cestodes and chewing lice and relatively less Plasmodium and coccidia had a more colourful bill, circulated more carotenoids and were heavier. These results suggest that bill colour more accurately reflects the relative intensities of parasite infection, rather than one-by-one relationships with parasites or absolute parasite burden. Investigating patterns of multiple parasite infection would thus improve our understanding of the information conveyed by coloured signals on parasite load.

Summary: 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.

Summary: Parasites have evolved a myriad of attachment structures closely adapted to their hosts and sites of attachment. Here, using members of the genus Acanthobothrium van Beneden, 1850 (Cestoda: Tetraphyllidea: Onchobothriidae), we (i) examined the influence of host body size and phylogeny, in addition to morphological features of these tapeworms, on the size of 3 structures used in attachment (bothridia, accessory suckers and hooks) by means of general linear models and phylogenetic-independent contrasts methods, and (ii) quantified the scaling exponents of relationships between size of attachment structures and tapeworm body size. Our results indicate that there exists a positive relationship, albeit not directly proportional, between size of attachment structures and Acanthobothrium spp. body size, and hook size and size of bothridia and accessory suckers. These results suggest that the resource investment in whole-body growth is greater than that in attachment structures, and that a greater investment in development of bothridia and accessory suckers is required to maintain an equivalent functional efficacy to hooks. In addition, host body size also influences, though less markedly, the size of attachment structures in Acanthobothrium spp. independently of parasite size itself. Acanthobothrium species have evolved a generalized mode of attachment that is successful in maintaining their position on various intestinal mucosal topographies across a variety of hosts exploiting different food resources.

This study is devoted to ultrastructural and immunosytochemical investigation of the nervous system in parasitic and free-living platyhelminthes to learn if glial cells exist in the nervous system of flatworms. We described the ultrastructure of different types of glial cells and the peculiarities of myelinization of gigantic axons; immunoreactivity to the S100b protein is revealed. Comparative analysis of the glia structure of annelids and platods is given; structural, functional, and evolutionary aspects of myelinization of gigantic axons, which are revealed in cestodes, are discussed.

Parasites found in the human gastrointestinal tract can be largely categorized into two groups, protozoa and helminths. The soil-transmitted helminths (Ascaris lumbricoides, hookworm and Trichuris trichiura) are the most prevalent, infecting an estimated one-sixth of the global population. Infection rates are highest in children living in sub-Saharan Africa, followed by Asia and then Latin America and the Caribbean. The current momentum towards global drug delivery for their control is at a historical high through the efforts of numerous initiatives increasingly acting in coordination with donors, governments and local communities. Together, they have delivered enormous quantities of drugs, especially anthelmintics to children through nationwide annual or biannual mass drug administration largely coordinated through schools. However, a much larger and rapidly growing childhood population in these regions remains untreated and suffering from more than one parasite. Mass drug administration has profound potential for control but is not without considerable challenges and concerns. A principal barrier is funding. Stimulating a research and development pipeline, supporting the necessary clinical trials to refine treatment, in addition to procuring and deploying drugs (and sustaining these supply chains), requires substantial funding and resources that do not presently exist. Limited options for chemotherapy raise concerns about drug resistance developing through overuse, however, satisfactory pharmaco-epidemiology and monitoring for drug resistance requires more developed health infrastructures than are generally available. Further, the limited pharmacopeia does not include any effective second-line options if resistance emerges, and the research and development pipeline is severely depressed. Herein, we discuss the major gastrointestinal protozoa and helminths reviewing their impact on child health, changing epidemiology and how this relates to their control.

This paper reports the parasites found in three commercially exploited bivalve molluscs (Mytella guyanensis, Anomalocardia brasiliana and Iphigenia brasiliana) of an estuarine region of Ilhéus, south of Bahia, Brazil (14 degrees 48'23''S; 39 degrees 02'47''W). Samples of 20 individuals of each species were collected fortnightly from August 2005 to August 2006. A total of 1480 individuals was collected and processed by standard histologic techniques; the histologic sections were stained with Harris haematoxylin and eosin and examined with light microscope. The water temperature in the study area varied from 24 to 30.5 degrees C and the salinity from 0 to 23ppt. Remarkable differences were found in the parasitic community between the three mollusc species involved in the study, which occupied different habitats in the estuarine region of the Cachoeira river. The following parasites were found: intracellular rickettsia-like colonies in digestive epithelia; intracellular gregarine Nematopsis sp. in gills, mantle, gonad, digestive gland and foot muscle; sporocysts of a Bucephalidae trematode in gonads, mantle, gills, digestive gland and foot; unidentified digenetic metacercariae in digestive gland and gonad; metacestodes of Tylocephalum sp. in connective tissue in the digestive gland and in gonad; and an unidentified metazoan in mantle and intestinal lumen. No significant temporal variation in the prevalence of any parasite was detected, which could be due to the narrow temperature range of the region and the absence of patterns of salinity and rainfall variation through the year. The infestation by sporocyst was the only pathological threat detected for the studied populations because of its potential for host castration. The low infection intensity and/or prevalence of the other parasites and the lack of obvious lesions suggest that there is no other serious pathological risk for the studied mollusc populations.

Within the distribution of Ligula intestinalis, a tapeworm affecting freshwater fishes, there are genetically distinct and well-separated phylogenetic clusters. East Africa is represented by a single monophyletic clade which is understudied compared with Euro-Mediterranean clades. The present field investigation in the Lake Baringo and Naivasha catchments, Kenya, revealed that this L. intestinalis clade was highly host-specific, present in only 2 of 12 fishes examined; Barbus paludinosus in Naivasha and Barbus lineomaculatus in Baringo. In infected fish, cestodes comprised up to 20% of body weight. Only 1 parasite was recorded per fish, a contrast to infected fishes in Europe where mixed infections are commonplace. In B. lineomaculatus in Baringo, only fish of greater than 64 mm in length were parasitized. The highest parasite prevalence was recorded in fish of 70-77 mm in length, and reduced for lengths of 78-84 mm. Parasitized fish were significantly associated with a particular type of habitat, occurring most frequently in shallow littoral areas, and being absent from open water and rocky shore habitats. Uninfected fish were present in all habitats. This relationship between spatial occupancy and parasite prevalence is suggested to arise from behavioural alterations induced by the parasite that promotes completion of the parasite life cycle.

Among tetraphyllidean cestodes, parasitic in the spiral valve of Raja asterias Delaroche, colected from Algerian coasts, we obtained an onchobothriid of the genus Acanthobothrium, differing from all species of Acanthobothrium previously reported from Rajidae from Mediterranea and european Atlantic coast. This Cestode is characterized by its very small size (1-2 mm), its number of segments of the strobila (4-8), the morphology and size of hooks, the limited number (17-25) of testes and ovarian morphology. Together, these features places this Acanthobothrium in group "2" as defined by Ghoshroy & Caira (2001). We describe this onchobothriid as Acanthobothrium minus n. sp.

In this investigation on endoparasites (helminths) and ectoparasites of the Nile rat (Arvicanthis niloticus Desmarest, 1822), a total of 220 Nile rats were trapped from different regions of Sudan during the period January 2003-January 2006. Examination of different tissues, identification of parasites, effect of these parasites on the organs, the prevalence and intensity of infestation of the parasites and their relation to the habitat of the host, and sex-related infestations were considered. Results showed that the variation among helminth species was wide, especially in those that are transferred by arthropods. No protozoan parasites or distortion in the infected tissues were observed. No examination for Toxoplasma gondii was carried out. Two species of cestodes (Hymenolepis nana, Hymenolepis diminuta), two genera (Raillietina sp. I, Raillietina sp. II) and one unidentified Hymenolepididae were reported. The most prevalent species of cestodes was Raillietina sp. And for nematodes only one species and one genus were recovered (Monanema nilotica and Streptopharagus sp.). Investigation of skin revealed that 83.8% of rats were infested with one or more of ectoparasites; namely, insects and arachnids. This survey also revealed that fleas and lice were the most common ectoparasites that infested the Nile rat. Synanthropic rodents, particularly those living in close association with man, play a significant role in human health, welfare and economy. It has to be stressed that their arthropod ectoparasites are important vectors of pathogenic microorganisms and they can also be important reservoirs for parasitic zoonoses, like trichinellosis and capillariosis. No doubt, the increase in rodent populations could be followed by an increase in zoonotic diseases (Stojcevic et al. 2004, Durden et al. 2000). Rats and mice (commensal and wild) play an important role in public health, being carriers or reservoirs for infectious diseases that can be transmitted to humans (zoonoses). Xenopsylla cheopis is the most important vector of plague and the rickettsial infection murine typhus (Gratz 1999). Man can also acquire the infection through direct contact with infected animals' tissues (WHO 1987). Arvicanthis niloticus, Mastomys natalensis and Rattus rattus are probably the most important and widespread reservoirs of plague in Kenya: 10 percent of all Rattus rattus tested were found to be positive as compared to 12% of the Arvicanthis niloticus (Gratz 1999)., (© 2009 ISZS, Blackwell Publishing and IOZ/CAS.)

The expulsion of the gastrointestinal parasite Vampirolepis nana was examined in different mouse strains and in immunosuppressed mice infected to different degrees with eggs and cysticercoids. To investigate the immunological mechanism that regulates expulsion, surface-bound mouse immunoglobulins were examined on adult worms. The time to spontaneous expulsion of worms was dependent on strain (C57BL, BDF(1), B6C3F(1)

It is still unclear whether flatworms have specialized glial cells. At present there are no special methods available for the identification of glial cells in flatworms. The aim of this research was to carry out detailed investigations of the CNS in two species ofcestodes, and to get an idea whether these cells may fit into the concept of glia. Three types of glial cells have been found in Grillotia erinaceus: (1) fibroblast-like cells in the cerebral ganglion (CG); (2) glial cells in bulbar nerves with filaments and laminar cytoplasm; (3) a 3rd type of cells forms multilayer envelopes in the main cords (MC); also they make contacts with the excretory epithelium. To demonstrate the existence of glial cells, an immunocytochemical and ultrastructural investigation of Ligula intestinalis was undertaken. Intensive S100b-like immunoreaction (IR) was found in the GG and in the MC. IR-varicosities were mostly located asymmetrically on the MC, and no IR was found in neuropiles. Small glial cells were found on the surface of the MC; they have oval nuclei and dense cytoplasm with slim processes going around the neuropile and enclosing neurons. Long junctions are seen between cell processes but with neurons they usually possess juxtaposition contacts. Glial cells lack vesicles or synapse-like structures. Intensive S100b-like-IR has been shown in the CNS of cestodes for the first time. Results from ultrastructural research support the immunocytochemical date.

Artemia franciscana is an invasive crustacean expanding its range in hypersaline wetlands in the Mediterranean region and replacing native Artemia parthenogenetica and Artemia salina. Native brine shrimps are known as intermediate hosts of cestodes; infected individuals exhibit changes in their behaviour and appearance, thus facilitating the parasite transmission to the avian hosts by predation. To assess whether invasive brine shrimps participate in the cestode life cycles to the same extent as the native species, we examined the natural infections in seven populations of Artemia spp. along the southern coast of Spain and Portugal: three populations of each A. franciscana and A. parthenogenetica and one population of A. salina. Ten cestode species were found in A. parthenogenetica, while only six were recorded in each of A. salina and A. franciscana. The overall infection was consistently higher in native than in invasive populations. For a particular cestode species, the prevalence or abundance was significantly higher in a native population for 54 pairwise comparisons and only higher for an invasive population for 4 pairwise comparisons. These results suggest that cestodes may influence competitive interactions between native and invasive brine shrimps, thus partly explaining the invasive success of A. franciscana.

Purpose of Review: This review summarizes the biology, clinical aspects, diagnosis, treatment and epidemiology for the common and rarer (zoonotic) intestinal cestodes of humans., Recent Findings: Mass drug application to eliminate Taenia solium carriers may have only temporary effects on cysticercosis transmission. At least two major world genotypes of T. solium have been identified and greater genetic heterogeneity may occur at the regional level. A new human taeniid T. asiatica has been confirmed which occurs sympatrically with T. saginata and T. solium in Southeast Asia. Coproantigen and PCR tests for Taenia spp. have greatly improved diagnostic efficacy and epidemiological studies. There appears to be an increase in human diphyllobothriasis in Europe, Japan and the Americas., Summary: Human intestinal cestode infections are globally primarily caused by species in three genera: Taenia, Hymenolepis or Diphyllobothrium. Sporadic zoonotic infections caused by nontaeniids are usually food-borne or due to accidental ingestion of invertebrate hosts. Intestinal cestode infections generally result in only mild symptoms characterized chiefly by abdominal discomfort and diarrhoea. Most human intestinal cestode infections can be treated with a single oral dose of praziquantel or niclosamide.

Specimens of fleas Ctenocephalides felis felis (1052 female symbol/448 male symbol), obtained from 150 dogs in Centro de Controle de Zoonoses de Belo Horizonte, Minas Gerais, Brazil, were dissected and examined for endosymbionts. Three protozoan, Nolleria pulicis, a gregarine (Actinocephalidae) and Leptomonas sp., together with one cestode, Dipylidium caninum were identified. Infections by N. pulicis and Leptomonas sp. occurred mainly in the warm-rainy period. The prevalence and distribution of these endosymbionts in fleas derived from Brazil and South America, and the their variation according to sex and season, are reported for the first time.

Lesions associated with two species of tapeworms within the digestive tract of wild-caught specimens of the bull shark, Carcharhinus leucas, and the sicklefin weasel shark, Hemigaleus microstoma, from Malaysian Borneo are described. Portions of the glandular stomach and pyloric gut with parasites were removed and fixed in 10% formalin buffered in sea water. Whole mounts, histological sections of tissues with and without worms in situ, and scanning electron microscopy images of detached worms were examined. Both species of cestodes belonged to the trypanorhynch family Tentaculariidae. Heteronybelinia estigmena was found in large numbers parasitizing the pyloric gut of C. leucas; an unidentified tentaculariid was found in relatively small numbers in both the glandular stomach and pyloric gut of H. microstoma. Both species burrowed their scoleces deeply in the mucosa and attached via hooked tentacles and unciniform microtriches of the scolex. The lesions induced by the parasites were marked in both sharks and ranged from acute necrotizing to chronic granulomatous gastroenteritis. Regenerative hyperplasia and intestinal metaplasia of gastric epithelium were also present. The severity and character of pathology was causally linked to the intensity of infection, the attachment mode of the parasites, and to the anatomophysiological relationships within the gut of the host shark.

Estimation of the standard metabolic rate (SMR), maximal oxygen consumption (MOC) and thermoregulation ability in males of red-backed vole (Clethrionomys rutilus Pallas, 1779) have shown that individuals infected with nematodes Heligmosomum mixtum, regardless of intensity of worm infection, had an increased level of oxygen consumption in the cold exposition, while the individuals infected with the cestodes Arostrilepis horrida, had a lover oxygen consumption than non-invaded individuals. Worm burden of A. horrida correlated negatively with MOC value in the hosts. Thermo-conductance of individuals infected with A. horrida was significantly lower than in ones infected with H. mixtum. Opposite effects of these two helminthes seems to be determined by the specificity of pathogenesis and different body mass of parasites. Total body mass of nematodes are usually less than 0.2% of the host body mass whereas the total body mass of cestodes may exceed 5% of the host body mass.

Metacestodes of Neogryporhynchus cheilancristrotus (Wedl, 1855) were found in the gut of some gibel carp (Carassius gibelio) specimens from a Hungarian water reservoir. Location of metacestodes in the freshly opened gut was marked with disseminated, red-coloured, pinhead-sized nodules in the anterior part of the intestine. In histological sections, metacestodes were found in a hole inside the propria layer of the intestinal folds. The worms were in direct contact with the host tissue without being encapsulated as a result of host reaction. In some specimens with extruded rostellum the rostellar hooks were bored into the host tissue and suckers grabbed pieces of the surrounding connective tissue. Around the worms, congested capillaries and formation of macrophages were seen in the lysed connective tissue.

Red fox (Vulpes vulpes) as reservoir of parasites and source of zoonosis. This review presents data from Europe and Poland on the prevalence of helminth and protozoan parasites in red foxes (Vulpes vulpes). The most common nematodes were geohelminths: Uncinaria stenocephala, Toxocara canis and Toxocara leonina. As concerning Trichinella genus T. britovi was found more often than T. spiralis. Among tapeworms the following species were recorded: Mesocestoides lineatus, Taenia sp., and Echinococcus multilocularis. Detected cases of E. multilocularis together with an increase of fox population during last few years create a potential human risk of infection. The results of many studies indicate rare presence of trematodes (Alaria alata) and protozoan parasites (Toxoplasma gondii, Neospora caninum, Leishmania spp., Eimeria spp.) in red foxes.

Recombinant DNA studies have been focused on developing vaccines to different cestodes. But few studies involving Dipylidium caninum molecular biology and genes have been done. Only partial sequences of mitochondrial DNA and ribosomal RNA gene are available in databases. Any molecular work with this parasite, including epidemiology, study of drug-resistant strains, and vaccine development, is hampered by the lack of knowledge of its genome. Thus, the knowledge of specific genes of different developmental stages of D. caninum is crucial to locate potential targets to be used as candidates to develop a vaccine and/or new drugs against this parasite. Here we report, for the first time, the sequencing of a fragment of a D. caninum expressed gene.

Intestinal helminths are an important cause of equine disease. Of these parasites, the Cyathostominae are the commonest group that infect horses. These nematodes consist of a complex tribe of 51 species, although individual horses tend to harbour 10 or so common species, in addition to a few rarer species. The Cyathostominae can be extremely pathogenic, and high levels of infection result in clinical symptoms ranging from chronic weight loss to colic, diarrhoea and death. As part of their life cycle, immature cyathostomins penetrate the large intestinal wall, where they can enter a state of inhibited larval development. These larvae can exist in this state for months to years, after which they subsequently re-emerge. If larvae re-emerge in large numbers (i.e. several million), severe pathological consequences ensue. The inhibited larvae are also relatively refractory to several of the currently available anthelmintics, so that horses treated previously with anthelmintics can still carry life-threatening burdens of these parasitic stages. Little is known about the cyathostomin larvae during their mucosal phase, and current research efforts are focused on investigating the biology of these stages. Much of the research described here highlights this area of research and details studies aimed at investigating the host immune responses that the mucosal larvae invoke. As part of this research effort, molecular tools have been developed to facilitate the identification of larval and egg stages of cyathostomins. These molecular tools are now proving very useful in the investigation of the relative contributions that individual, common cyathostomin species make to the pathology and epidemiology of mixed helminth infections. At the more applied level, research is also in progress to develop an immunodiagnostic test that will allow numbers of mucosal larvae to be estimated. This test utilises antigen-specific IgG(T) serum antibody responses as markers of infection. As anthelmintic resistance will be the major constraint on the future control of the Cyathostominae, researchers are now actively investigating this area and studies aimed at elucidating the molecular mechanisms of drug resistance are described. Another parasite which has assumed a clinically important role in horses is the tapeworm, Anoplocephala perfoliata. This parasite is prevalent world-wide and has been shown to be a significant cause of equine colic. Because previous methods of estimating the infection intensity of tapeworm were inaccurate, recent research has been directed at developing an immunodiagnostic ELISA for these cestodes. Specific IgG(T) responses to antigens secreted by adult tapeworms have been shown to provide a reasonable indication of infection intensity. An ELISA based on these responses is now commercially available. The steps involved in the development of this ELISA are described here. In addition to these recent advances in research, this review also outlines the principle areas for future research into these important equine parasites.

Larvae (metacestodes) of tapeworms of the cyclophyllidean family Gryporhynchidae (previously included in the Dilepididae) occur in different internal organs of fresh- and brackish water fish (110 fish species of 27 families in 12 orders reported), which serve as the second intermediate hosts. The species composition, spectrum of fish hosts, sites of infection, and geographical distribution of gryporhynchids recorded from fish are reviewed here on the basis of literary data and examination of extensive material from helminthological collections. Metacestodes of the following genera have been found in fish: Amirthalingamia Bray, 1974 (1 species), Ascodilepis Guildal, 1960 (1), Cyclustera Fuhrmann, 1901 (4), Dendrouterina Fuhrmann, 1912 (1), Glossocercus Chandler, 1935 (3), Neogryporhynchus Baer et Bona, 1960 (1), Paradilepis Hsü, 1935 (5), Parvitaenia Burt, 1940 (2), and Valipora Linton, 1927 (3). However, most published records concern only three species, namely Neogryporhynchus cheilancristrotus (Wedl, 1855) from the intestinal lumen, Paradilepis scolecina (Rudolphi, 1819) from the liver and mesenteries, and Valipora campylancristrota (Wedl, 1855) from the gall bladder of cyprinids and other fish in the Palaearctic Region. Data on other species as well as reports from other regions are very scarce and almost no information is available from Australia, tropical Asia and South America. A recent study of gryporhynchid metacestodes from Mexico (Scholz and Salgado-Maldonado 2001), which reported 13 species, suggested that they may be more common than indicated by records in the literature. Although only a few cases of pathogenic influence of larvae on fish hosts have been reported, the veterinary importance of gryporhynchids remains to be assessed on the basis of more detailed studies. The data available indicate a strict host and site specificity of some species whereas others occur in a wide spectrum of fish hosts and are not strictly site-specific. Evaluation of Paradilepis larvae from the liver of salmonid fish from British Columbia, Canada, identified as P. simoni Rausch, 1949 by Ching (1982), has shown that they probably belong to two species, P. simoni and P. rugovaginosus Freeman, 1954. Metacestodes of the latter species and those of Cyclustera magna (Baer, 1959) from the intestinal wall of Tilapia zillii (Gervais) from Kenya are reported from fish for the first time.

Increased antioxidant enzymatic activities were observed in carp parasitised by Ptychobothrium sp. when compared with healthy fish. This antioxidant response could contribute to neutralise the oxidative stress normally induced by parasitism.

This paper reviews the literature on zoonotic cestode infections with specific reference to the years 1999-2003. The sources and prevalence of various zoonotic tapeworm infections caused by adult and larval stages of the genera Taenia, Echinococcus, Diphyllobothrium, Hymenolepis and Dipylidium continue to be an important cause of morbidity and mortality, not only in most underdeveloped countries but also in industrialized countries, particularly in rural areas or among immigrant groups from endemic areas. The review gives a detailed report on recent molecular epidemiological studies on the taxonomy and phylogenetic variations in Echinococcus granulosus, immunological tests and imaging techniques used in epidemiological surveys and clinical investigations of important adult and larval tapeworm infections of animals and humans. Larval stages or metacestodes of Taenia solium, Echinococcus spp. and pseudophyllidean tapeworms (Spirometra syn. Diphyllobothrium spp.) may reside in various tissues of their intermediate hosts, including humans. In particular, Cysticercus cellulosae (T. solium) and the larvae of E. granulosus, and E. multilocularis, which are predominantly located in the liver, lungs and central nervous system forming various types of cysts, lead to a complex of systemic diseases such as cysticercosis, cystic echinococcosis and alveolar echinococcosis, respectively. Relatively rare clinical manifestations are seen in the muscles, subcutaneous tissue, spleen, kidneys, bones and body cavities.

Seasonal occurrence in terms of prevalence, intensity of infection, abundance and density of the tapeworm Proteocephalus longicollis (Zeder, 1800) and its transmission between its intermediate host (Cyclops abyssorum prealpinus) and definitive host (common whitefish, Coregonus lavaretus) in Lake Annecy, an oligotrophic lake in the western part of the Alps, France, were studied in the period of 1998-2000. A copepod Cyclops abyssorum prealpinus (Kiefer, 1939), the dominant species among planktonic crustaceans in the lake, served as the only intermediate host for this parasite. Infection with plerocercoids was higher in adult copepods (predominantly females) than in copepodite stages IV and V. The prevalence rate of 25% found in C. abyssorum prealpinus females in June 1998 represents a unique infection rate of intermediate hosts with fish tapeworms in natural conditions. The final host, the common whitefish Coregonus lavaretus (L.), was heavily infected with P. longicollis throughout the year (prevalence 90%; mean abundance 40.3; maximum intensity of infection more than 500 tapeworms per fish); immature tapeworms predominated in all samples (P<0.01). Transmission of tapeworm larvae from copepods to the common whitefish took place most intensively in summer and autumn, and depended on seasonal changes in the density of the C. abyssorum prealpinus population, infection of this copepod with plerocercoids and their density in the lake. In addition, transmission efficiency also seems to be determined by the longevity of tapeworm larvae in the intermediate host, timing of predation of the fish host and rapid development of the parasite within this host during the summer period. Overall transmission potential of P. longicollis was low, with only about 9% of juvenile specimens reaching maturity in common whitefish.

This study shows that ingestion of Schistocephalus solidus coracidia was related to general activity of Macrocyclops albidus copepods at the time of exposure. The lower the activity of the host, the fewer parasites it ingested. In an earlier study it was shown that large M. albidus copepods were less likely to become infected with S. solidus than small copepods, which could potentially be caused by differential ingestion of parasites. However, the current study did not show any evidence for such an effect arising through differential ingestion. Body size was not related to ingestion of parasites, but was positively correlated to activity. So, even though size did not significantly relate to ingestion of parasites, if anything, through their higher activity large copepods rather than small copepods may have ingested more parasites. This study indicates that differences in resistance to this parasite do not come about through differential ingestion of parasites. Also, an earlier study failed to show differential elimination of the parasite from the haemocoel. This leaves avoidance of penetration through the gut wall as the most plausible candidate causing large copepods to be more resistant to this parasite than small copepods.

The occurrence, prevalence and infection intensity of proteocephalidean larvae in naturally infected intermediate hosts of the Upper Paran River floodplain are reported. A total of 5,206 zooplanktonic and benthic organisms were analyzed, namely cyclopid (2,621) and calanoid (1,479) copepods, cladocerans (704), rotifers (307), chironomid larvae (41) and ostracods (54). Eight cyclopid copepods - two copepodids, one male and five females - comprising 0.3% of the cyclopid copepods examined, were naturally infected. The male infected belonged to a species of Paracyclops, and the females to Paracyclops sp., Thermocyclops minutus and Mesocyclops longisetus.

Trophic relationships between 10 species of fish host and their associated nematode, cestode, and copepod parasites were investigated using stable isotopes of carbon and nitrogen. Nematodes and cestodes were consistently depleted in 15N with respect to their host, and such fractionation patterns are unlike those conventionally observed between consumers and their diets. Species of copepod parasite were sometimes depleted and sometimes enriched in 15N with respect to fish hosts, and this confirms earlier reports that the nature and magnitude of ectoparasite-host fractionations can vary. Significant differences in delta15N and delta13C were observed among fish tissues, and the isotopic signature of parasites did not always closely correspond to that of the tissue with which the parasite was found most closely associated, or on which the parasite was thought to be feeding. Several possible explanations are considered for such discrepancies, including selective feeding on specific amino acids or lipids, migration of the parasite among different fish tissues, changes in the metabolism of the parasite associated with life history and migration between different host animals.

An increased antioxidant response (catalase, glutathione S-transferase (GST) and glutathione reductase (GRd) activities in liver and GST activity in head kidney) was observed in carp parasitized by Ptychobothrium sp. compared to healthy fish. In case of a copper contamination of these fish, the decrease in enzymatic activities observed was less pronounced in parasitized than in healthy carp.

The occurrence of the crowding effect was demonstrated in plerocercoids of the cestode Schistocephalus solidus infecting threespine stickleback Gasterosteus aculeatus from Walby and Scout lakes, Alaska. Contrary to an earlier report, relatively large numbers of parasites (>3-4 plerocercoids) were observed to grow large enough in an intermediate host fish to become competent to infect and to mature in the definitive host under any of 3 assumed threshold values and 1 scenario of graded sizes for parasite competency. In Walby Lake, intensity and host body mass were significant predictors of mean plerocercoid mass per host, whereas intensity, host body mass, and combined parasite index were significant predictors in Scout Lake. Slopes of equations expressing the relationship between mean parasite mass and intensity for both lakes were less than 1, implying that processes other than or in combination with simple resource limitation might be producing the observed crowding effect. The causal mechanism for the crowding effect could include exploitative competition, interference competition, and host immune response. There were significant differences in infection between the two lakes, including different distributions of parasite intensities among hosts and different expressions of the crowding effect; however, an explanation of the differences awaits further investigation.

Transmission by Gyrodactylus turnbulli occurs most frequently when its hosts (Poecilia reticulata) come into close contact. This study is the first description of a specific migratory behavior that facilitates transmission of a gyrodactylid from dead hosts. Recently-dead guppies typically float at the water's surface; G. turnbulli moves off these fish into the water film, hanging motionless with the haptor held by surface tension. Because guppies are surface feeders, detached parasites in the water film are more likely to contact a new host.

'Good genes' models of sexual selection suggest that elaborate male sexual ornaments have evolved as reliable signals of male quality because only males of high genetic viability are able to develop and maintain them. Females benefit from choosing such individuals if quality is heritable. A key prediction is that the offspring of males with elaborate mating displays will perform better than those of less elaborate males, but it has proved difficult to demonstrate such an effect independently of the effects of differences in parental investment. We tested for 'good genes' linked to male ornamentation in the three-spined stickleback Gasterosteus aculeatus using in vitro fertilization to generate maternal half-siblings, which were raised without parental care. Maternal half-siblings sired by brightly coloured males grew less quickly than half-siblings sired by dull males but were more resistant to a controlled disease challenge. Among the offspring that became infected, those with brighter fathers had higher white blood cell counts. This suggests that highly ornamented males confer disease resistance on their offspring. The association with reduced growth suggests a mechanism for the maintenance of heritable variation in both disease resistance and male sexual coloration.

Parasites impose an energetic cost upon their hosts, yet, paradoxically instances have been reported in which infection is associated with enhanced, rather than diminished, host growth rates. Field studies of these parasite effects are problematic, since the pre-infection condition of the hosts is generally unknown. Here, we describe a laboratory experiment in which the growth rate and body condition of 76 laboratory-reared three-spined stickleback fishes were examined before, during and after each fish was fed the infective stage of the parasitic cestode Schistocephalus solidus. Twenty-one of these fishes went on to become infected by the cestode. Fishes were individually housed and provided with an abundant food supply to eliminate the potentially masking effects of variable competitive ability. Infection occurred independently of fish gender, size, body condition or pre-exposure growth rate. After exposure to the cestode, infected fishes grew faster (excluding parasite weight) and maintained a similar or better body condition compared with uninfected fishes, despite developing enlarged spleens. The accelerated growth could not be explained by reduced gonadal development. This result, one of few demonstrations of parasite-associated growth enhancement in fishes, is discussed with respect to other such parasite systems.

Factors affecting the abundance of Triaenophorus crassus and Triaenophorus nodulosus procercoids in their copepod first intermediate host, Cyclops strenuus, and effects of infection on feeding behaviour, reproduction and survival of the host were studied experimentally. When exposed to the same number of coracidia, copepods harboured considerably less procercoids in the trials where ciliates or Artemia salina nauplii were given as alternative food items. The prevalence of infection was higher in adult copepods as compared with copepodite stage IV and stage V, and higher in stage V than in stage IV. The prevalences in adult females and males did not differ significantly from each other. The frequency of females carrying egg sacs was lower among infected than among exposed uninfected and unexposed copepods. The rate of feeding on Artemia nauplii remained at the same level in uninfected copepods, but decreased strongly in infected copepods during 7 days p.i. The survival of unexposed, exposed uninfected and infected copepods did not differ significantly from each other for the first 11 days post-exposure, but the mortality of infected copepods increased significantly after 3 weeks post-exposure. However, the rate of development and mortality of copepods might have been affected by the apparently arrested development of stage IV copepodites found in the experiment. Some of the contradictions between these results and earlier observations are suggested to be caused by the differences in the duration of exposure, intensity of infection and duration of observation post-exposure in the present study as compared with other experiments.

Poultry now accounts for 30% of all meat consumed. Parasites are a problem where ever poultry are raised, whether in large commercial operations or in small back-yard flocks, and economic losses can be significant. This paper will briefly review the major protozoan, helminth, and arthropod species in poultry including pathogenesis. Other topics will include the importance of the interaction of other diseases and parasites, and control of the infection by chemotherapy, management, and immunity.

Proteins and reducing sugars were assayed. The total proteolytic and amylolytic activities were determined in flushes of body cavity of the breams infected and noninfected by plerocercoids Ligula intestinalis. Infection with L. intestinalis markedly affected the composition of the medium and the activity of enzymes functioning in the body cavity of the bream: protein content increased, total proteolytic activity remained practically unchanged, while the content of reducing sugars and total amylolytic activity decreased. The strength of fixation of amylolytic enzymes on the surface of L. intestinalis tegument was tested. The dynamics of desorption of these enzymes from the tegument of plerocercoids and adult cestodes parasitizing in the fish intestine. The contents of protein and glycogen do not depend on the cestode length and strobile region.

Until recently, the equine tapeworm Anoplocephala perfoliata was difficult to diagnose and considered to be of questionable pathogenicity. Here, Chris Proudman and Sandy Trees describe recent advances in the immunodiagnosis of this parasite that have facilitated epidemiological studies. These studies suggest that A. perfoliata may be an important cause of intestinal disease in the horse and demonstrate a dose-response relationship between infection intensity and risk of disease. If tapeworm infection is a risk factor for ileocaecal colic, the identification and treatment of infected individuals would be a rational approach to disease prevention.

We report the first isotopic study of an animal host-parasite system. Parasitic, intestinal nematodes, Graphidium strigosum and Passalurus ambiguus, were 15N-enriched relative to their host, the European rabbit Oryctolagus cuniculus, while parasitic cestodes, Cittataenia denticulata and Mosgovoyia pectinata, were 15N-depleted, suggesting different trophic relationships. Host embryos were more similar in their delta 13C and delta 15N values to maternal muscle than were any of the parasites. Coprophagy, the direct recycling of food by the rabbit eating its own faeces, did not lead to isotopic differences between stomach contents and faeces, suggesting that the major point for isotopic discrimination in lagomorph nitrogen metabolism is in the animal rather than in the gut. We conclude that bulk delta 13C and delta 15N can reveal valuable new information about host-parasite relationships, and these could be explored further at the biochemical level using compound-specific isotopic analyses.

In an experiment to study the infectivity, growth and virulence of Schistocephalus solidus in their first intermediate host, copepods of the species Macrocyclops albidus were kept singly and exposed to up to 9 coracidia. Eleven or 14 days post-infection (p.i.) the presence and growth of the cestode larvae relative to survival, growth and reproduction of their host was determined. As expected, the probability of a copepod becoming infected increased with increasing numbers of parasites administered. However, the chances of a single coracidium establishing in a copepod also increased with increasing numbers of coracidia administered, which indicates that the parasites profit from a dilution effect of the host's defence. Copepod size or developmental stage had no significant effect on the infection, but 14 days p.i., constraining effects of copepod size on the growth of the parasites were apparent. Moreover, procercoids in multiple infections grew smaller and developed their cercomer at a smaller size than those in single infections. No significant effect of the parasite on host mortality was found within the observation period. However, growth between the 5th copepodid stage and adult stage was negatively affected by infection. An infection with S. solidus was also strongly linked with host reproduction: infected females were more likely to bear an egg sac at the end of the experiment than non-infected ones. These egg sacs, however, contained fewer eggs.

DNA/DNA hybridization has been carried out to establish the evolutionary relationships among several host-specific bothriocephalid tapeworms species (Cestoda: Platyhelminthes). Comparative anatomy is not informative for deciphering the relationships among these sibling morphological taxa, and clearcut genetic differences have previously identified seven biological species which are each highly specific to a single host. We show that two species (Bothriocephalus gregarius and B. renaudii) infesting the same host (turbot: Psetta maxima) in two different geographic areas are not sister-taxa. Moreover, a strong decrease in the amount of DNA change is observed in one species of tapeworm, documenting a marked heterogeneity of rates of nucleotidic substitution among these very closely related organisms. Based on these observations, different hypotheses are developed for understanding the evolutionary history of this assemblage of parasites, suggesting that host-switching has played an important role in the recent past.

Population dynamics, site selection, growth and maturation of the cestode Eubothrium crassum in a natural population of Salmo trutta in a small lake were studied over a period of 1 year, the life-span of a cohort in fish. Infection of fish commenced in spring but peaked in July. Small, plerocerciform parasites initially located in the intestine, but then some moved into the pyloric caecae whilst others, the majority in heavy infections, were lost from the fish causing a fall in abundance from 460 to 10 over 2 months. This mortality was density dependent. Initially, parasites were distributed more evenly throughout the caecae but as time increased larger parasites were found preferentially in the anterior caecae before moving back into the intestine when gravid, preparatory to being lost in the following summer. Only a small proportion of the infrapopulation became gravid. Although the proportion of caecae occupied was initially density dependent, by the time of maturation several preferred anterior caecae remained unoccupied and mean intensity always exceeded unity. Neither growth nor maturation was affected by intraspecific competition. It was concluded that caecal availability did not set a limit or threshold of infrapopulation density, and in this respect E. crassum-S. trutta differed from some acanthocephalan-fish systems but was similar to others. Heavy infection followed by heavy mortality appeared to be typical of this parasite-host system in other localities, and of several other cestode-fish systems. The implications of this for population regulation are discussed.