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Amebiasis, a global intestinal parasitic disease, is due to Entamoeba histolytica. This parasite, which feeds on bacteria in the large intestine of its human host, can trigger a strong inflammatory response upon invasion of the colonic mucosa. Whereas information about the mechanisms which are used by the parasite to cope with oxidative and nitrosative stresses during infection is available, knowledge about the contribution of bacteria to these mechanisms is lacking. In a recent study, we demonstrated that enteropathogenic Escherichia coli O55 protects E. histolytica against oxidative stress. Resin-assisted capture (RAC) of oxidized (OX) proteins coupled to mass spectrometry (OX-RAC) was used to investigate the oxidation status of cysteine residues in proteins present in E. histolytica trophozoites incubated with live or heat-killed E. coli O55 and then exposed to H2O2-mediated oxidative stress. We found that the redox proteome of E. histolytica exposed to heat-killed E. coli O55 is enriched with proteins involved in redox homeostasis, lipid metabolism, small molecule metabolism, carbohydrate derivative metabolism, and organonitrogen compound biosynthesis. In contrast, we found that proteins associated with redox homeostasis were the only OX-proteins that were enriched in E. histolytica trophozoites which were incubated with live E. coli O55. These data indicate that E. coli has a profound impact on the redox proteome of E. histolytica. Unexpectedly, some E. coli proteins were also co-identified with E. histolytica proteins by OX-RAC. We demonstrated that one of these proteins, E. coli malate dehydrogenase (EcMDH) and its product, oxaloacetate, are key elements of E. coli-mediated resistance of E. histolytica to oxidative stress and that oxaloacetate helps the parasite survive in the large intestine. We also provide evidence that the protective effect of oxaloacetate against oxidative stress extends to Caenorhabditis elegans., Competing Interests: The authors have declared that no competing interests exist.

The pathogenic potential of Blastocystis sp. in experimental models requires further investigation. In this work, the pathogenicity of this parasite in the gastrointestinal tract of male Swiss mice was evaluated according to the inoculum size and period of infection. Animals were infected intragastrically, with 100, 500, 1,000, 5,000 and 10,000 Blastocystis sp. vacuolar forms obtained from a mixture of eight human isolates cultured axenically in Jones' medium. After seven, 14, 21, 28 and 60 days of infection, the animals were sacrificed and fragments of the small intestine (duodenum), large intestine, and cecum were subjected to histopathological analysis. Blastocystis sp. triggered an inflammatory response in the different tissues analyzed, with a predominance of mononuclear cells. The parasite was found in the muscular layer of the cecum, showing its invasive character. Larger inocula triggered inflammatory processes earlier (seven days) than smaller ones (from 21 days). We conclude that, in the proposed model, the pathogenicity of Blastocystis sp. isolates that were studied is related to inoculum size and period of infection.

Unlabelled: Prion diseases are infectious neurodegenerative disorders characterized by accumulations of abnormally folded cellular prion protein in affected tissues. Many natural prion diseases are acquired orally, and following exposure, the early replication of some prion isolates upon follicular dendritic cells (FDC) within gut-associated lymphoid tissues (GALT) is important for the efficient spread of disease to the brain (neuroinvasion). Prion detection within large intestinal GALT biopsy specimens has been used to estimate human and animal disease prevalence. However, the relative contributions of the small and large intestinal GALT to oral prion pathogenesis were unknown. To address this issue, we created mice that specifically lacked FDC-containing GALT only in the small intestine. Our data show that oral prion disease susceptibility was dramatically reduced in mice lacking small intestinal GALT. Although these mice had FDC-containing GALT throughout their large intestines, these tissues were not early sites of prion accumulation or neuroinvasion. We also determined whether pathology specifically within the large intestine might influence prion pathogenesis. Congruent infection with the nematode parasite Trichuris muris in the large intestine around the time of oral prion exposure did not affect disease pathogenesis. Together, these data demonstrate that the small intestinal GALT are the major early sites of prion accumulation and neuroinvasion after oral exposure. This has important implications for our understanding of the factors that influence the risk of infection and the preclinical diagnosis of disease., Importance: Many natural prion diseases are acquired orally. After exposure, the accumulation of some prion diseases in the gut-associated lymphoid tissues (GALT) is important for efficient spread of disease to the brain. However, the relative contributions of GALT in the small and large intestines to oral prion pathogenesis were unknown. We show that the small intestinal GALT are the essential early sites of prion accumulation. Furthermore, congruent infection with a large intestinal helminth (worm) around the time of oral prion exposure did not affect disease pathogenesis. This is important for our understanding of the factors that influence the risk of prion infection and the preclinical diagnosis of disease. The detection of prions within large intestinal GALT biopsy specimens has been used to estimate human and animal disease prevalence. However, our data suggest that using these biopsy specimens may miss individuals in the early stages of oral prion infection and significantly underestimate the disease prevalence., (Copyright © 2015 Donaldson et al.)

Gross and histological lesions caused by an intestinal parasite were described in three capybaras. The parasites presented a mean length of 14 mm and width of 7 mm, were round to oval or piriform, reddish and pedunculated, and adhered strongly to the mucosa of the large intestine. The intestinal mucosa at the parasite attachment site presented loss of surface epithelium and most glands, with replacement by fibrovascular proliferation that protruded from the mucosa and was involuted by the ventral sucker of the parasite. The lamina propria presented cellular debris, eosinophils, macrophages and plasma cells. The morphological characteristics, observed using serial histological sections, made it possible to classify the parasite as a trematode (Paramphistomatidae), compatible with Taxorchis schistocotyle. One capybara also harbored many ciliated protozoa in the large intestine (at the site of attachment of the parasite) and inside the caeca of the trematodes. In conclusion, this study described a multifocal necrotizing colitis associated with T. schistocotyle parasitism in capybaras.

Strongyluris dracocola n. sp. from the intestine of Lophognathus temporalis collected in Papua New Guinea is described and illustrated. Strongyluris dracocola n. sp. represents the 32nd species assigned to the genus and the sixth from the Australo-Papuan region. It can be easily separated from the other Australo-Papuan species because it is the only species to have an unpaired median papilla adjacent to the sucker.

The migration of lymphocytes to the small intestine is controlled by expression of the integrin α4β7 and the chemokine receptor CCR9. However, the molecules that specifically regulate migration to the large intestine remain unclear. Immunity to infection with the large intestinal helminth parasite Trichuris muris is dependent upon CD4(+) T cells that migrate to the large intestine. We examine the role of specific chemokine receptors, adhesion molecules and glycosyltransferases in the development of protective immunity to Trichuris. Mice deficient in expression of the chemokine receptors CCR2 or CCR6 were resistant to infection with Trichuris. Similarly, loss of CD34, CD43, CD44 or PSGL-1 had no effect on resistance to infection. In contrast, simultaneous deletion of the Core2 β1,6-N-acetylglucosaminyltransferase (C2GnT) enzymes C2GnT1 and C2Gnt2 resulted in delayed expulsion of worms. These results suggest that C2GnT-dependent modifications may play a role in migration of protective immune cells to the large intestine.

Spauligodon bonairensis n. sp. from the large intestines of the Antilles gecko, Gonatodes antillensis (Lacertidae), from Bonaire, Lesser Antilles, is described and illustrated. The new species is the 48th assigned to the genus and the 10th from the Neotropical region. Spauligodon bonairensis n. sp. is most similar to S. giganticus, S. hemidactylus, S. lamonthei, and S. oxkutzcabiensis in that only these 5 species possess lanceolate eggs. For males of these species, only S. lamothei possess a spicule, and only S. oxktzcabiensis has an aspinose tail. The egg of S. hemidactylus has 2 knobs; in S. giganticus, the more rounded end supports the single knob. In S. bonairensis n. sp., the more pointed end supports the single knob.

Objective: The aim of this study was to determine the cytological features of 2 endocommensal ciliates, P. colpoidea and P. minuta belonging to genus Paraisotricha found in the hindgut of 15 Turk rahvan and 15 English and Arabic horses from Izmir, compare the morphological characters of species with their original descriptions and previous reports and discuss the similarities and differences., Methods: The cytological features of two endocommensal ciliates were investigated with the pyridinated silver carbonate impregnation and silver nitrate impregnation techniques at the level of light microscopy., Results: Specimens from our horses were found to be similar to the original descriptions on the basis of cytological features, morphological characters and biometric data., Conclusion: We have concluded that the geographical variation and feeding habits of the host animals are important for evaluating the biometric data of species.

The present study was conducted on 31 males and females of the European bison, eliminated during the winter seasons 2007-2011 in the Białowieza Primeval Forest, Poland. The caeca of 14 free-ranging bison, aged from 3 months up to 16 years, the most favorable infection site for the large intestine nematodes, were investigated during the winter of 2007/2008. The parasitological autopsies of the large intestines of 9 free-ranging bison aged from 5 months up to 10 years as well as 9 bison kept in the close reserves aged from one up to 20 years were done during the winter seasons of 2008-2011 to determine localization of nematodes in large intestine and the total intensity of parasite infection. Five species of nematodes (i.e., Trichuris ovis, Oesophagostomum venulosum, O. radiatum, Ashworthius sidemi, Nematodirus helvetianus) were found in dissected caecum of bison culled during the winter of 2007/2008. During the seasons of 2008-2010, 6 species of nematodes were found in the large intestine of bison (i.e., T. ovis, O. venulosum, O. radiatum, A. sidemi, N. roscidus and Bunostomum trigonocephalum). We did not find any nematodes in the lumen of the large intestine of captive bison culled during the seasons of 2010/2011. The results of the present study indicate that the intensity of infection by the large intestine nematodes of the European bison in the Białowieza Primeval Forest has stayed at the comparable level throughout the last 20 years; however the number of nematode species has increased. The observed level of parasitic infection is typical of subclinical parasitoses.

Background: Mouse angiogenin 4 (Ang4) has previously been described as a Paneth cell-derived antimicrobial peptide important in epithelial host defence in the small intestine. However, a source for Ang4 in the large intestine, which is devoid of Paneth cells, has not been defined., Methodology/principal Findings: Analysis was performed on Ang4 expression in colonic tissue by qPCR and immunohistochemistry following infection with the large intestine dwelling helminth parasite Trichuris muris. This demonstrated an increase in expression of the peptide following infection of resistant BALB/c mice. Further, histological analysis of colonic tissue revealed the cellular source of this Ang4 to be goblet cells. To elucidate the mechanism of Ang4 expression immunohistochemistry and qPCR for Ang4 was performed on colonic tissue from T. muris infected mouse mutants. Experiments comparing C3H/HeN and C3H/HeJ mice, which have a natural inactivating mutation of TLR4, revealed that Ang4 expression is TLR4 independent. Subsequent experiments with IL-13 and IL-4 receptor alpha deficient mice demonstrated that goblet cell expression of Ang4 is controlled either directly or indirectly by IL-13., Conclusions: The cellular source of mouse Ang4 in the colon following T. muris infection is the goblet cell and expression is under the control of IL-13.

Aplectana novaeguineae n. sp. (Ascaridida, Cosmocercidae) from the intestines of Sphenomorphus pratti (Squamata: Scincidae) is described and illustrated. Aplectana novaeguineae n. sp. represents the 48th species assigned to the genus and the 5th species of the genus reported from the Australo-Papuan region. It is most similar to Aplectana leesi, Aplectana linstowi , and Aplectana krausi in that females of only these 4 species exhibit a swollen anterior vulvar lip. These 4 species may be separated by spicule length and caudal papillae arrangement. Spicules of A. linstowi and A. krausi are less than 200 µm in length, A. leesi between 200 and 250 µm, and A novaeguineae greater than 400 µm. Aplectana linstowi possesses 18 post cloacal papillae, A. leesi and A. krausi each possess 10, and A. novaeguineae possesses 8. In addition, Paraleptonema ranae has been assigned to Aplectana as Aplectana fujianae nom. nov.

Entamoeba histolytica is a human pathogen that causes amoebic dysentery and leads to significant morbidity and mortality worldwide. Understanding the genome and evolution of the parasite will help explain how, when and why it causes disease. Here we review current knowledge about the evolutionary genomics of Entamoeba: how differences between the genomes of different species may help explain different phenotypes, and how variation among E. histolytica parasites reveals patterns of population structure. The imminent expansion of the amount genome data will greatly improve our knowledge of the genus and of pathogenic species within it., (Copyright © 2011 Institut Pasteur. Published by Elsevier SAS. All rights reserved.)

Parapharyngodon bainae n. sp. (Nematoda:Pharyngodonidae) collected from the small intestine of Tropidurus torquatus (Squamata:Tropiduridae) is described. The new species is the 47 th species in the genus and the 14 th in the Neotropical region. The morphology of male posterior end, ovary position in females, and egg size can be used to differentiate P. bainae from the other congeneric species. Parapharyngodon rotundatus , Parapharyngodon sanisfaciecaudus , and Parapharyngodon riojensis are most closely related to P. bainae. In males of P. sanisfaciecaudus and P. rotundatus , the cloacal lip has a smooth appearance, whereas in P. bainae , males have an echinate cloacal lip. Parapharyngodon riojensis differs from P. bainae because its females have postbulbar ovaries, the eggs are larger, and the esophagi are larger in both sexes. Parapharyngodon spp. nematodes occupy an intermediate phylogenetic position among pharyngodonid parasite lineages in carnivorous and herbivorous reptiles. The average low intensity of infection for P. bainae (4.8 ± 4.6) is typically found in carnivorous reptiles. This fact and the high prevalence value (60%) can be explained by the ingestion of environmental substrata material containing parasite eggs while foraging.

Skrjabinodon aspercaudus n. sp. from the large intestine of Pholidobolus montium (Gymnophthalmidae) from Ecuador is described and illustrated. Skrjabinodon aspercaudus represents the 29th species assigned to the genus and the 6th species from the neotropical region. The new species differs from all other species assigned to Skrjabinodon by the presence of small bosses on the surface of the tail filament of both males and females. In addition to the new species, P. montium harbored the cestode, Cairaella henrii, and third-stage larvae of a species of Physaloptera.

The inhabitants of the mammalian gut are not always relatively benign commensal bacteria but may also include larger and more parasitic organisms, such as worms and protozoa. At some level, all these organisms are capable of interacting with each other. We found that successful establishment of the chronically infecting parasitic nematode Trichuris muris in the large intestine of mice is dependent on microflora and coincident with modulation of the host immune response. By reducing the number of bacteria in the host animal, we significantly reduced the number of hatched T. muris eggs. Critical interactions between bacteria (microflora) and parasites (macrofauna) introduced a new dynamic to the intestinal niche, which has fundamental implications for our current concepts of intestinal homeostasis and regulation of immunity.

A Cosmocercoides sauria n. sp., an intestinal parasite of the gymnophthalmid lizard Iphisa elegans from western Brazil, is described. Of the 18 species previously described, C. sauria represents the 19th species, and is the third to be reported in the Neotropical region. Moreover, C. sauria is the second species reported from a reptilian host and is distinguished by a smaller number of rosette papillae (4 pairs). Additionally, the new species can be distinguished from the other Neotropical species (Cosmocercoides lilloi Ramallo, Bursey and Goldberg, 2007 and C. variabilis (Harwood, 1930)) by possessing smaller spicule size and presence of both gubernaculum and lateral alae in Cosmocercoides lilloi .

Rokroknema novaebritanniae n. gen., n. sp. (Nematoda: Pharyngodonidae) from the large intestine of Platymantis nexipus (Anura: Ranidae) is described and illustrated. Rokroknema represents the second Australo-Papuan genus assigned to the family Pharyngodonidae known to infect frogs. It is similar to Parathelandros (the other genus), but it is readily distinguished because the posterior pair of caudal papillae is not in the form of a rosette. Platymantis nexipus also was found to harbor 1 species of Digenea, Opisthioglyphe cophixali, and 5 additional species of Nematoda, adults of Aplectana krausi, Cosmocerca novaeguineae, Falcaustra batrachiensis, Icosiella papuensis, and larvae in cysts of Abbreviata sp., plus unidentified cystacanths of 1 species of acanthocephalan.

Trichuris muris is a natural mouse model of the human gastrointestinal nematode parasite Trichuris trichiura and it is well established that a T helper type 2-dominated immune response is required for worm expulsion. Macrophages accumulate in the large intestine of mice during infection and these cells are known to express the mannose receptor (MR), which may act as a pattern recognition receptor. The data presented here show for the first time that T. muris excretory/secretory products (E/S) induce bone-marrow-derived macrophages (BMDM) to produce several cytokines and have MR-binding activity. Using alternatively activated BMDM from MR knockout mice it is shown that the production of interleukin-6 partially depends on the MR. Infection of MR knockout mice with T. muris reveals that this receptor is not necessary for the expulsion of the parasite because MR knockout mice expel parasites with the same kinetics as wild-type animals and have similar cytokine responses in the mesenteric lymph nodes. Furthermore, despite acting to reduce serum levels of proinflammatory mediators, absence of the MR does not lead to increased gut inflammation after T. muris infection when assessed by macrophage influx, goblet cell hyperplasia and crypt depth. This work suggests that, despite binding components of T. muris E/S, the MR is not critically involved in the generation of the immune response to this parasite.

Three nematodes, Turgida turgida, Cruzia americana, and Didelphostrongylus hayesi, have been documented to cause morbidity and mortality in the Virginia opossum (Didelphis virginiana). The present study was designed to determine the frequency of infection of these nematodes in opossums at 2 study sites in California and to determine if there are risk factors associated with shedding of eggs or larvae in the feces. Turgida turgida and C. americana adults were found in 84.4% (stomach; n = 45) and 62.5% (intestinal wash and feces; n = 16) of sampled opossums. Eggs were present in opossum feces (n = 105) less frequently (40% T. turgida and 35.2% C. americana). Didelphostrongylus hayesi larvae were found in 79.0% of opossum feces examined (n = 105). Adult age and wet season (December through April) were significant predictive factors for the presence of T. turgida eggs, whereas the dry season (May through November) was significantly associated with the presence of C. americana eggs in feces. Adult opossums were more likely to have eggs and larvae from all 3 nematodes in the feces.

Enterobius (Colobenterobius) colobis Vuylstéke, 1964 (Nematoda: Oxyuridae) is redescribed based on males and females collected from an ashy red colobus, Procolobus rufomitratus tephrosceles (Elliot, 1907) (Primates: Cercopithecidae: Colobinae), in Uganda. Two morphotypes are recognized among females, which are readily distinguished by tail length, termination level of lateral alae, and egg size. The relative position of cellular wall greatly varied in the ovijector, indicating its limited systematic value. The males possess a much shorter spicule than those in previous descriptions, suggesting the presence of polymorphism.

Helminths down-regulate inflammation and may prevent development of several autoimmune illnesses, such as inflammatory bowel disease. We determined if exposure to the duodenal helminth Heligmosomoides polygyrus establishes cytokine pathways in the distal intestine that may protect from intestinal inflammation. Mice received 200 H. polygyrus larvae and were studied 2 weeks later. Lamina propria mononuclear cells (LPMC) were isolated from the terminal ileum for analysis and in vitro experiments. Mice with H. polygyrus were resistant to trinitrobenzenesulfonic acid (TNBS)-induced colitis, a Th1 cytokine-dependent inflammation. Heligmosomoides polygyrus did not change the normal microscopic appearance of the terminal ileum and colon and minimally affected LPMC composition. However, colonization altered LPMC cytokine profiles, blocking gamma interferon (IFN-gamma) and interleukin 12 (IL-12) p40 release but promoting IL-4, IL-5, IL-13, and IL-10 secretion. IL-10 blockade in vitro with anti-IL-10 receptor (IL-10R) monoclonal antibody restored LPMC IFN-gamma and IL-12 p40 secretion. IL-10 blockade in vivo worsened TNBS colitis in H. polygyrus-colonized mice. Lamina propria CD4(+) T cells isolated from colonized mice inhibited IFN-gamma production by splenic T cells from worm-free mice. This inhibition did not require cell contact and was dependent on IL-10. Heligmosomoides polygyrus colonization inhibits Th1 and promotes Th2 and regulatory cytokine production in distant intestinal regions without changing histology or LPMC composition. IL-10 is particularly important for limiting the Th1 response. The T-cell origin of these cytokines demonstrates mucosal regulatory T-cell induction.

Skrjabinodon dixoni n. sp. from the large intestine of Uracentron flaviceps (Squamata: Iguanidae) from Peru is described and illustrated. It is also reported in the same host from Ecuador. Skrjabinodon dixoni n. sp. differs from other species assigned to Skrjabinodon by morphology of tail filament and number of tail filament spines.

A new genus, Paracosmocercella (Nematoda: Cosmocercoidea: Cosmocercidae), is proposed with monotypic Paracosmocercella rosettae n. sp. from the Japanese tree frog, Hyla japonica Günther, 1859, in Oita, Kyushu Island, Japan. Paracosmocercella resembles Cosmocercella and Cosmocercoides by having 2 rows of rosette papillae without plectanes ventrally in preanal region of male, but it is readily distinguished from Cosmocercella by lacking clear vesicle supporting rosette papillae and from Cosmocercoides by lacking rosette papillae in perianal region and having large-sized eggs, which hatch in uterus.

Aplectana tarija n. sp. and Cosmocercoides lilloi n. sp., intestinal parasites of the toad Chaunus arenarum, are described. Of the 41 nominal species of Aplectana, A. tarija n. sp. represents the 22nd Neotropical species and the second species reported from Argentina. Of the 14 nominal species of Cosmocercoides, C. lilloi n. sp. represents the 15th species and the first species reported from South America.

Parapharyngodon baueri n. sp. (Nematoda: Pharyngodonidae) from the large intestine of the legless skink, Typhlosaurus lineatus, is described and illustrated. Parapharyngodon baueri is the 42nd species assigned to the genus and differs from other species in the genus by possessing four pairs of caudal papillae, no cloacal lip adornment, and a sharply pointed spicule of 79-98 microm. The cestode, Oochoristica truncata, the nematode, Thubunaea fitzsimonsi, third-stage nematode larvae and acanthocephalan cystacanths were also present.

Aspidodera sogandaresi n. sp. (Heterakoidea: Aspidoderidae) from Dasypus novemcinctus Linnaeus, 1758 is herein described. This nematode occurs in armadillos from as far south as the canal zone of Panama, north through central Mexico, and into the southern United States. Previously identified as Aspidodera fasciata (Schneider, 1866), this new species has blunt projections on the lips and lateral expansions at the distal tips of the spicules, whereas A. fasciata has conspicuous digitiform projections on the lips, and a terminal round expansion at the tips of the spicules. Other species of the family present in North America include Aspidodera binansata Railliet and Henry, 1913; Aspidodera vazi Proença, 1937; and Lauroia trinidadensis Cameron, 1939.

Helminth parasites were collected from 14 raccoon dogs (Nyctereutes procyonoides viverrinus) and 2 Japanese weasels (Mustela itatsi sho) on Yakushima Island, Kagoshima Prefecture (Kyushu), Japan. In addition to trematodes and nematodes reported separately, everted cystacanths of 3 bird acanthocephalans (Mediorhynchus robustus in 5 animals, Porrorchis leibyi in 2 animals, and Sphaerirostris lanceoides in 1 animal) were collected from the raccoon dogs introduced recently on this World Natural Heritage Area. A cystacanth of P. leibyi was collected also from a weasel indigenous to this island that were killed by traffic accidents. Recovery of everted cystacanths of M. robustus from the intestine of raccoon dogs was remarkably frequent (36%), suggesting that this acanthocephalan should be highly prevalent in passerine hosts on Yakushima Island, and the animals might vigorously take insect hosts or paratenic hosts. Furthermore, the present report is the second on M. robustus after its first record in Japan (Aichi Prefecture, Honshu) as M. garruli from a Eurasian jay (Garrulus glandarius japonicus) by Yamaguti in 1939. Porrorchis leibyi has never been recorded in Japan.

Anuracanthorhynchus tritaxisentis n. gen., n. sp. from the intestines of the Brazilian frog Hylodes phyllodes (Leptodactylidae) is described and illustrated. Anuracanthorhynchus tritaxisentis n. gen., n. sp., is unique among the echinorhynchid Acanthocephala by possessing a spherical proboscis supporting a small number of hooks of equal size. It is the sixth acanthocephalan species reported from South American anurans.

We report a case of fatal Strongyloides stercoralis (S. stercoralis) infection in a 35-year-old female with lupus glomerulonephritis after prolonged steroid therapy. An epidemiological evaluation revealed that our patient originated from a rural area in Bosnia and Herzegovina, which was an endemic region of S. stercoralis infection in the former Yugoslavia. She had severe gastrointestinal and pulmonary symptoms and history of a 13 kg weight loss in 3 months. Histopathological examination of large bowel mucosa showed nematode larvae. Microscopy of stool, sputum and urine samples confirmed S. stercoralis. The diagnosis was delayed because of the low suspicion index, the absence of eosinophilia and non-specific signs of infection, which could be a result of the underlying disease or the effects of corticosteroids. This case highlights the importance of screening for S. stercoralis in patients starting immunosuppressive therapy, especially if they are from endemic areas. Timely diagnosis and therapy could save the patient's life.

The large intestine of a rat has been neglected almost completely as a site of Strongyloides sp. infection. We reported that adult Strongyloides ratti remained in the large intestine for more than 80 days, producing more number of infective larvae than small intestine adults, and therefore hypothesized that parasitism in this site could be a survival strategy. In wild rats, however, no study has focused on large intestine infections of Strongyloides. The present study revealed that 32.4% of 68 wild rats, Rattus norvegicus, had the infection of S. ratti in the large intestine, with an average of 4.7 worms. These worms harbored normal eggs in the uterus. In a laboratory experiment with S. ratti and Wister rats, daily output of infective larvae by 4.7 females in the large intestine was estimated to be 4,638.4, suggesting that a few parasites could play a role in the parasite transmission. Five species of nematode found in the wild rats showed seasonality in infection intensity, with highest intensities in March-May. The number of S. ratti in the large intestine was also highest in these months.

Helminths of mountain reedbuck (Redunca fulvorufula fulvorufula) and gray rhebok (Pelea capreolus) were investigated in South Africa between June 1999 and February 2002. Forty-one mountain reedbuck were culled at Sterkfontein Dam Nature Reserve over 8 different periods, and 25 mountain reedbuck were culled at Tussen die Riviere Nature Reserve over 3 different periods. A total of 17 kinds of helminths were found at the 2 sites, including 15 nematodes, 1 trematode, and 1 cestode. At Sterkfontein, the most prevalent and abundant species were Cooperia yoshidai, Longistrongylus schrenki, and Haemonchus contortus, with the latter 2 being more abundant during November/December than at other times of the year, probably because infective larvae increased on pasture at that time. No statistical differences were found in parasite loads between male and female mountain reedbuck. No correlation was found between fecal egg counts and adult worm counts or between parasite counts and body condition. At Tussen die Riviere, helminths in mountain reedbuck were less prevalent and abundant than at Sterkfontein. The most important species were Nematodirus spathiger, Trichostrongylus falculatus, and Cooperia rotundispiculum. Four gray rhebok died of natural causes at Sterkfontein, from which 5 kinds of helminths were recovered, including C. yoshidai and Paracooperioides peleae.

The functional integrity of the intestinal epithelial barrier forms a major defense against invading pathogens, including gastrointestinal-dwelling nematodes, which are ubiquitous in their distribution worldwide. Here, we show that an increase in the rate of epithelial cell turnover in the large intestine acts like an "epithelial escalator" to expel Trichuris and that the rate of epithelial cell movement is under immune control by the cytokine interleukin-13 and the chemokine CXCL10. This host protective mechanism against intestinal pathogens has implications for our wider understanding of the multifunctional role played by intestinal epithelium in mucosal defense.

Parapharyngodon kenyaensis n. sp. and Thelandros samburuensis n. sp. (Nematoda: Pharyngodonidae) from the large intestine of the agamid lizard (Agama caudospina) are described and illustrated. Parapharyngodon kenyaensis n. sp. is the 41st species assigned to the genus, and it differs from other species in that genus by possessing 3 pairs of caudal papillae, cloacal lip adornment, and spicules of 112-120 microm in length. Thelandros samburuensis n. sp. is the 31st species assigned to the genus, and it differs from other species in that genus by possessing swollen posterior annulations, 6 caudal papillae, a smooth anterior cloacal lip, and spicules of 43-52 microm in length. In addition to the 2 new nematode species, Abbreviata ortleppi (Nematoda: Physalopteridae) and Strongyluris ornata (Nematoda: Heterakidae) were found.

The therapeutic effect of clindamycin on Eimeria pragensis (E. pragensis) infection in C57BL/6 mice was demonstrated by suppression of oocyst production and the appearance of degenerated endogenous stages of parasite in the intestine. Short-term clindamycin treatment, from 1 to 4 days or 4 to 8 days post infection (pi) at a dose of 800 mg/kg/day was effective to reduce clinical symptoms, oocyst production and schizogonic development. Interestingly, the short-term treatment schedules allowed the development of a measurable degree of protective immunity to challenge infection in the treated mice. In contrast, clindamycin treatment for the full 12 days period, which almost completely inhibited clinical symptoms and oocyst output, prevented the full development of protective immunity in the treated mice. All these data indicate that clindamycin is efficacious as an anti-eimerian agent and that both early and late endogenous developmental stages of E. pragensis exert a deep influence on the development of effective immunity to challenge infection.

Spinicauda fisheri n. sp. from the intestine of Platymantis pelewensis collected in the Palau Islands, Republic of Belau, is described and illustrated. Spinicauda fisheri represents the 12th species assigned to the genus and the first from Oceanica. It is most similar to Spinicauda spinicauda in that the tail ends in a filament, but it has 19 pairs of caudal papillae as compared with 5 pairs in S. spinicauda. In addition to S. fisheri, 2 species of Cestoda, cysticercoids of Joyeuxiella sp. and tetrathyridia of Mesocestoides sp., 2 species of Nematoda, Oswaldocruzia bakeri and Physocephalus sp. (larvae in cysts), 1 species of Acanthocephala, Acanthocephalus bufonis, and 1 species of Pentastomida, nymphs of Kiricephalus pattoni were identified.

The initial phases of invasion of mammalian coccidia of the genus Eimeria into host tissue are still poorly known. This process, including the passage of oocysts through the intestinal lumen, excystation of sporozoites, their penetration into epithelial cells and migration to the target site was studied in both naive and immune mice infected with Eimeria falciformis. After oral infection, the intact oocysts were transported with enteral contents to the large intestine, where the excystation of sporozoites and their penetration into superficial epithelium took place. The sporozoites subsequently migrated into the epithelium of crypts, which is the specific site of asexual multiplication. The immune status of the hosts did not affect the passage of oocysts, excystation and penetration of sporozoites. However, the migration of sporozoites towards their target site (crypts) was impeded in immune mice and sporozoites tended to remain in superficial mucosa rather than migrate to the crypts.

Two hundred and forty-four specimens of Parapharyngodon riojensis n. sp. were found in the large intestines of 2 adult lizards Phymaturus punae collected from Quebrada del Leoncito, Province of La Rioja, Argentina. Parapharyngodon riojensis n. sp. represents the ninth species of the genus from the Neotropical Realm and the first species to be described from Argentina. It can be distinguished from all species of Parapharyngodon on the basis of the morphology of the anterior cloacal lip, the location of the ovary, and geographical distribution. Parapharyngodon riojensis n. sp. is most similar to P. senisfaciecaudus in that the ovary does coil around the esophagus and the number and location of caudal papillae in the males are the same. These 2 species differ in that the eggs of P. senisfaciecaudus are slightly asymmetrical, with a smooth, thin shell, whereas the eggs of P. riojensis are oval, with a punctate thick shell. In addition, the cloacal lip of males of P. senisfaciecaudus is smooth, whereas the cloacal lip of males of P. riojensis is echinate. A key to the species of Parapharyngodon in the Neotropical Realm is provided.

Africana telfordi n. sp. (Nematoda: Heterakidae) from the large intestine of the lizard Enyalioides heterolepsis collected in Panama is described and illustrated. Africana telfordi n. sp. represents the seventh species assigned to the genus and the second from the Neotropical Realm. It is distinguished from the other neotropical species, A. chabaudi, by the size and shape of the spicules. The spicules of A. telfordi are robust, analate, and 366-458 microm in length; those of A. chabaudi are narrow, alate, and 644-869 microm in length.

Objective: To establish clinical features, course of illness, and treatment outcome of cats with diarrhea and concurrent infection with Trichomonas organisms. Prevalence of fecal trichomonads in a geographically comparable population of healthy indoor and feral cats also was assessed., Design: Longitudinal study and a cohort study., Animals: 32 cats with diarrhea and naturally acquired trichomonosis that were native to North Carolina, Virginia, Connecticut, and Tennessee; 20 healthy indoor cats; and 100 feral cats., Procedure: Trichomonosis was diagnosed in 32 cats by identification of organisms in fresh feces or by protozoal culture of feces., Results: Diarrhea associated with the large intestine and trichomonosis were diagnosed in 32 cats. Median age of the cats was 9 months; 23 cats were < or = 1 year old at the time of diagnosis. Two cats developed diarrhea accompanied by infection with Trichomonas organisms after the addition of an infected kitten into the home. Duration of diarrhea ranged from 2 days to 3 years. Six cats had a coexisting enteric infection. Treatment with antimicrobials improved fecal consistency and reduced the number of flagellates in the feces, but did not eliminate infection. Diarrhea (with microscopically detectable flagellates) was observed shortly after antibiotics were discontinued. Trichomonads were not recovered from feces of any healthy indoor or feral cats., Conclusions and Clinical Relevance: Our findings suggest that trichomonosis may be a cofactor in development of diarrhea in young cats. Trichomonas organisms were not identified as part of the indiginous fauna of healthy indoor or feral cats.

A survey of whipworms was conducted in llamas and vicuñas in northwestern Argentina. Fecal examinations of a group of 14 llamas (April 1995-March 1996) and 69 vicuñas (November 1996) indicated a high prevalence (usually >50%) of Trichuris sp. in these hosts. Prevalence was highest during July-November 1995 that also coincided with the highest mean fecal egg count. During postmortem examinations of 1 llama and 1 vicuña, specimens of Trichuris tenuis were recovered from the cecum/large intestine of each camelid. This is the first report of T. tenuis in South America, and the first report in the vicuña. It is suggested that T. tenuis is the typical whipworm of aboriginal camelids.

Sarcocystis neurona is a protozoan parasite that causes a neurological disease in horses called equine protozoal myeloencephalitis. The route of transmission is speculated to be by fecal-oral transfer of sporocysts shed from opossums. Controversy exists regarding both the natural life cycle for this parasite as well as the species identity of opossum Sarcocystis. To provide stage-specific material for species comparison, 27 opossums from southern Michigan were screened for Sarcocystis spp. sporocysts. Seven opossums were positive for Sarcocystis sporocysts by fecal flotation. A simplified, effective technique for isolation, excystation, and culture of opossum Sarcocystis sp. from mucosal scrapings was developed. All 7 Sarcocystis sp. isolates were successfully cultured to grow long term in equine dermal cells to the merozoite stage. Merozoites were observed between 5 and 15 days after inoculation. In conclusion, opossums shed Sarcocystis sp. sporocysts that may be manipulated to excyst and grow in vitro in equine dermal cell lines to the merozoite stage using the simplified technique described.

Spauligodon ovifilus n. sp. (Nematoda: Pharyngodonidae) from the large intestines of the gecko Diplodactylus stenodactylus is described and illustrated. Prevalence of infection was 50% (mean intensity 5.9 +/- 6.3, range 1-21). Spauligodon ovifilus n. sp. represents the thirty-fifth species to be assigned to this genus and is distinguished by the extremely long filament of the egg. This is the first report of species of Spauligodon from Australia. In addition, 1 gecko harbored 1 female of Wanaristrongylus papangawurpae, a new host record; 1 gecko harbored 1 encapsulated larva of Abbreviata sp. Review of species assigned to Spauligodon caused the reclassification of Spauligodon azerbajdzanicus to Skrjabinodon azerbajdzanicus n. comb.

In the winter of 1997-1998, we collected parasitological data from 60 wild carnivora in the north-western part of Tohoku region, Japan. These included 7 foxes (Vulpes vulpes japonica), 20 raccoon dogs (Nyctereutes procyonoides viverrinus), 29 martens (Martes melampus melampus), 3 weasels (two Mustela sibirica itatsi and one M. nivalis namiyei), and one Japanese badger (Meles meles anakuma). Roundworms (Toxocara canis in foxes and Toxocara tanuki in raccoon dogs), hookworms (Ancylostoma kusimaense and Arthrostoma miyazakiense) and Molineus sp. in the small intestine were the most prevalent in foxes and raccoon dogs. In martens, Aonchotheca putorii in the stomach, Concinnum ten in the pancreatic duct, Molineus sp. and Euryhelmis costaricensis in the small intestine were the most prevalent. Collected parasites include some new helminth species for this region or Japan; the strobilar stage of Taenia polyacantha from foxes, Pygidliopsis summa from a raccoon dog, Eucoleus aerophilus, A. putorii, and Soholiphyme baturini from martens.

Digestive tract helminths of the Virginia opossum (Didelphis virginiana) were examined for site specificity and interspecific interactions. Thirty opossums were live-trapped at 2 localities in Georgia, killed, and their digestive tracts removed and divided into the following sections; esophagus, stomach, small intestine (20 equal sections), cecum, and large intestine (5 equal sections). Helminths present in each section were identified and counted. Three trematode, 1 cestode, 2 acanthocephala, and 6 nematode species were found. Two parasites (the acanthocephalan Centrorhynchus spinosus and the nematode Viannaia hamata) are new state records for Georgia and this is the first report of C. spinosus from an opossum. There was considerable overlap between the spatial distributions of many of the helminth species found in the small intestine though most species had different modal locations. Helminth species locations were unaffected by host sex or trapping locality. There was no evidence that the presence, absence, or intensity of any helminth species affected the location or intensity of other helminth species in the digestive tract.

Parasitologic, clinicopathologic, and pathologic aspects of Schistosoma japonicum infections of varying durations and intensities were studied in growing pigs injected intramuscularly with a dose of either 0, 100, 500, or 2,000 cercariae and killed at 4, 11, 17, or 24 weeks postinfection (PI). The number of viable worm pairs decreased significantly in the high dose group after 11 weeks PI but not in the lower dose groups; however, a stable population of immature worms persisted throughout the study in all dose groups. Liver egg counts also tended to decrease in the high dose group after 11 weeks but not in the other groups. Fecal egg excretion began at six weeks PI, was highest at eight weeks PI with a pronounced peak occurring only in the high dose group, and then decreased to low levels by 14 weeks PI in all groups. Egg counts from the feces as well as the liver correlated strongly with worm pair numbers during the acute phase of infection. The only clinicopathologic abnormality observed was an increase in circulating eosinophils corresponding to cercarial dose in all infected pigs by week six with peak counts occurring between six and eight weeks PI. The pigs exhibited no clinical signs of disease aside from diarrhea at the onset of patency. However, lesions were present throughout the large intestine of all infected pigs from 11 weeks PI, gradually decreasing with time. Severe liver fibrosis occurred in the 500 and 2,000 dose groups mainly at 11 weeks PI and then decreased in severity. In the liver, but not in the intestine, the severity of lesions at all time points was proportional to the cercarial dose given. The results indicate that after several weeks of patency, pigs with high intensities of S. japonicum infection are able to effectively eliminate the majority of adult worms while maintaining a stable population of immature schistosomes.

A study was made of the early migratory pattern of Ascaris suum in mice. Mice were each inoculated orally with a single dose of 2,500 infective eggs and then killed at 2, 4, 6, 8, 10, and 12 hr postinoculation (PI). At necropsy, it was observed that the larvae had penetrated the mouse cecum and colon and had reached the liver by 4 hr PI. This migratory behavior closely mimics what is observed in the pig and suggests that the mouse may serve as an experimental model for intestinal immunity in the early phase of A. suum infection.

A series of 849 male pinworms collected from a 64-yr-old Japanese male was examined. They were classified by the spicule morphology into 87 Enterobius vermicularis (Linnaeus, 1758), 754 Enterobius gregorii Hugot, 1983, and 6 immature adults, whereas 2 worms lacked spicules. The worm length of E. vermicularis was significantly larger than E. gregorii. The shape and length of the distal tubular portion of the spicule were identical in these forms, whereas the basal portion was different. The immature adults just after the final molt or still within the cuticle of the fourth stage had only a distal tubular portion, indicating that the basal portion is added during subsequent development. Moreover, various transitional forms were observed in the spicule morphology in the worms with intermediate body size between E. vermicularis and E. gregorii, showing that the basal portion of the spicule of E. vermicularis develops after the completion of E. gregorii-type basal portion. It is suggested that E. gregorii is a young stage of E. vermicularis.

Helminth-free donor pigs were inoculated with infective larvae of Oesophagostomum dentatum. Five weeks later, the donor pigs were killed to recover the adult worms. By nonsurgical rectal transplantation, 6 groups of helminth-free recipient pigs were then given different female-to-male ratios (FMR) of O. dentatum worms (10% females [F], 50% F, 90% F) at either high (300 worms) or low (30 worms) doses. Fecal egg excretions were measured once weekly following transplantation until the pigs were killed 4 wk posttransplantation to assess the worm burdens and their location. There was a strong and significant correlation between numbers of male and female worms located in the different sections of the large intestine, suggesting that the worm sex as well as physiological factors in the pig intestine may govern the location of the worms. There were no significant differences in fecal egg counts or female worm fecundity between any of the groups. However at the low dose level, the female worm fecundity was markedly lower in the L10% F group than in the 2 other groups, thus suggesting for low worm densities an upper threshold for the FMR above which O. dentatum females produce fewer eggs.

Two species of nematodes, Alaeuris mexicana n. sp. and Ozolaimus ctenosauri Caballero, 1938, were found in the iguanid lizard Ctenosaura pectinata (Wiegmann) from Aguamilpa, Nayarit, central Mexico (Pacific region). The new species, A. mexicana, differs from all congeners mainly in the length of the spicule (0.228-0.233 mm) and in the shape and size of the tail and caudal alae. Ozolaimus ctenosauri (syn. Ozolaimus prolixa Caballero et Cerecero, 1943) is considered a valid species parasitic in Ctenosaura spp. Scanning electron microscopic studies of both species revealed substantial differences in the structure of the mouth, which were used for the separation of the closely related genera Ozolaimus and Alaeuris.