Cryptosporidium abrahamseni n. sp. (Apicomplexa: Cryptosporidiiae) from red-eye tetra (Moenkhausia sanctaefilomenae).

The morphological, biological, and molecular characterisation of Cryptosporidium piscine genotype 7 from red-eye tetras (Moenkhausia sanctaefilomenae) are described, and the species name Cryptosporidium abrahamseni n. sp. is proposed. Histological analysis of intestinal tissue identified large numbers of Cryptosporidium organisms along the epithelial lining of the intestine. Sequence and phylogenetic analysis at 18S rRNA (18S) and actin loci conducted on intestinal scrapings revealed that C. abrahamseni n. sp. was genetically distinct from other Cryptosporidium species. At the 18S locus, it was most closely related to C. huwi (3.2% genetic distance) and exhibited genetic distances ranging from 5.9 to 6.5% (C. molnari) to 14.9% (C. scolpthalmi) from all other Cryptosporidium species. At the actin locus, the genetic distances were larger and C. abrahamseni n. sp. exhibited 10.3% genetic distance from C. huwi, and 17.6% (C. molnari) to 28% (C. canis) genetic distance from other Cryptosporidium spp. Phylogenetic analysis of concatenated 18S and actin sequences confirmed that C. abrahamseni n. sp. shares the closest genetic relationship with C. huwi (6.7% genetic distance), while the genetic distance between C. abrahamseni n. sp. and other Cryptosporidium spp. ranged from 12.1% (C. molnari) to 20.4% (C. canis). Based on genetic and histological data, C. abrahamseni n. sp. is validated as a separate species.

Helminths in the gastrointestinal tract as modulators of immunity and pathology.

Helminth parasites are highly prevalent in many low- and middle-income countries, in which inflammatory bowel disease and other immunopathologies are less frequent than in the developed world. Many of the most common helminths establish themselves in the gastrointestinal tract and can exert counter-inflammatory influences on the host immune system. For these reasons, interest has arisen as to how parasites may ameliorate intestinal inflammation and whether these organisms, or products they release, could offer future therapies for immune disorders. In this review, we discuss interactions between helminth parasites and the mucosal immune system, as well as the progress being made toward identifying mechanisms and molecular mediators through which it may be possible to attenuate pathology in the intestinal tract.

Temporal trends of intestinal parasites in patients attending a tertiary care hospital in south India: A seven-year retrospective analysis.

BACKGROUND & OBJECTIVES: Intestinal parasitic infections and their associated complications are a major cause of morbidity in the developing world. This retrospective study was done to assess the prevalence of intestinal parasitic infections among patients in a tertiary healthcare setting and to analyze age-, gender- and time-related trends in the prevalence of these intestinal parasites over a seven year period (2006-2012). METHODS: The presence of various intestinal parasites in a tertiary care setting over a seven year period in different age groups was determined by performing routine stool microscopy. Modified acid-fast staining was performed for stool samples collected from children less than five years of age for the detection of intestinal coccidian parasites. Statistical analysis was carried out to analyze age-related trends in relation to the prevalence of commonly detected intestinal parasites. Seasonal fluctuations in parasite prevalence were evaluated by performing harmonic regression analysis. RESULTS: A total of 257,588 stool samples were received over the seven year period for examination. The highest percentage of intestinal parasites was in the 6-10 yr age group. Among the intestinal parasites, Giardia intestinalis had the highest prevalence across most age groups, except in those above 60 yr of age where hookworm became more prevalent. A significant decreasing trend with age was observed for G. intestinalis, whereas for hookworm and Strongyloides stercoralis, an increasing trend with age was seen. Significant linear temporal trends were observed for parasites such as G. intestinalis, Entamoeba histolytica and Ascaris lumbricoides. INTERPRETATION & CONCLUSIONS: While G. intestinalis was more common in the younger age groups, certain soil-transmitted helminths such as hookworm and S. stercoralis showed a higher prevalence in the older populations. Significant temporal trends and seasonality were observed for some of the common intestinal parasites.

Morphological and histochemical changes associated with massive infection by Neoechinorhynchus buttnerae (Acanthocephala: Neoechinorhynchidae) in the farmed freshwater fish Colossoma macropomum Cuvier, 1818 from the Amazon State, Brazil.

The study describes the morphological changes associated with parasitism by the intestinal acanthocephalan Neoechinorhynchus buttnerae in tambaqui juveniles Colossoma macropomum farmed in an excavated nursery, in Manaus (Amazon) in September 2013. After fish biometrics, analysis of macroscopic changes in morphology and counting of parasites, bowel fragments were fixed and submitted to histological and histochemical processing. All fish analyzed had acanthocephalans in the intestine; intestinal loops were milky white in color, with the presence of nodules with heavy parasitism. The changes in tissues that form the intestine varied according to the arrangement of the parasites: either free in the intestinal lumen or fixed by the proboscis on the organ wall. In the first case, the changes found were flaking, abrasion, compression, hypertrophy of goblet cells and disappearance of the villi on the mucosa, leukocytic cell infiltration in the submucosa, and muscle layer thickening. In the second case, in addition to these, other changes were observed as metaplasia in muscle tissue with its replacement by a loose connective tissue with severe leukocytic infiltration, edema in blood vessels, and necrotic foci. The histochemical analysis revealed that positive Alcian Blue mucosal cells (pH 2.5) were more expressive in parasitized intestines than in intestines not parasitized by N. buttnerae.

Dientamoeba fragilis, One of the Neglected Intestinal Protozoa.

Dientamoeba fragilis is a single-celled protozoan, closely related to the trichomonads. Reported worldwide as causing human gastrointestinal symptoms, D. fragilis is very common and is second only to Blastocystis spp. Dientamoebiasis equals or exceeds the incidence of giardiasis. This minireview includes diagnostic options, clinical relevance, therapy, an animal model, the confirmed cyst stage, and sequencing data. The development of a rodent model, fulfilling Koch's postulates, and the confirmation of a cyst stage have clarified transmission routes, including fecal-oral transmission. The prevalence of D. fragilis varies between 0% to over 82%; results depend on the geographic location, group studied, and diagnostic methods used.

IL-22 mediates goblet cell hyperplasia and worm expulsion in intestinal helminth infection.

Type 2 immune responses are essential in protection against intestinal helminth infections. In this study we show that IL-22, a cytokine important in defence against bacterial infections in the intestinal tract, is also a critical mediator of anti-helminth immunity. After infection with Nippostrongylus brasiliensis, a rodent hookworm, IL-22-deficient mice showed impaired worm expulsion despite normal levels of type 2 cytokine production. The impaired worm expulsion correlated with reduced goblet cell hyperplasia and reduced expression of goblet cell markers. We further confirmed our findings in a second nematode model, the murine whipworm Trichuris muris. T.muris infected IL-22-deficient mice had a similar phenotype to that seen in N.brasiliensis infection, with impaired worm expulsion and reduced goblet cell hyperplasia. Ex vivo and in vitro analysis demonstrated that IL-22 is able to directly induce the expression of several goblet cell markers, including mucins. Taken together, our findings reveal that IL-22 plays an important role in goblet cell activation, and thus, a key role in anti-helminth immunity.

Loss of the TGFß-activating integrin αvß8 on dendritic cells protects mice from chronic intestinal parasitic infection via control of type 2 immunity.

Chronic intestinal parasite infection is a major global health problem, but mechanisms that promote chronicity are poorly understood. Here we describe a novel cellular and molecular pathway involved in the development of chronic intestinal parasite infection. We show that, early during development of chronic infection with the murine intestinal parasite Trichuris muris, TGFß signalling in CD4+ T-cells is induced and that antibody-mediated inhibition of TGFß function results in protection from infection. Mechanistically, we find that enhanced TGFß signalling in CD4+ T-cells during infection involves expression of the TGFß-activating integrin αvß8 by dendritic cells (DCs), which we have previously shown is highly expressed by a subset of DCs in the intestine. Importantly, mice lacking integrin αvß8 on DCs were completely resistant to chronic infection with T. muris, indicating an important functional role for integrin αvß8-mediated TGFß activation in promoting chronic infection. Protection from infection was dependent on CD4+ T-cells, but appeared independent of Foxp3+ Tregs. Instead, mice lacking integrin αvß8 expression on DCs displayed an early increase in production of the protective type 2 cytokine IL-13 by CD4+ T-cells, and inhibition of this increase by crossing mice to IL-4 knockout mice restored parasite infection. Our results therefore provide novel insights into how type 2 immunity is controlled in the intestine, and may help contribute to development of new therapies aimed at promoting expulsion of gut helminths.

Impairment of host resistance to helminthes with age in murine small intestine.

Age-associated alterations of Th2 immune responses against nematode parasites are largely unknown. We investigated primary and memory responses against two types of gastrointestinal nematode parasites, Heligmosomoides polygyrus (Hp) and Nippostrongylus brasiliensis (Nb), in aged mice. The small intestinal gene expression of Th2 cytokines was almost unchanged after primary (Nb and Hp) and secondary infection (Hp) in aged mice in contrast to strongly increased small intestinal gene expression of Th2 cytokines in young (3-month-old) mice. Mucus production decreased (Nb), and worm expulsion was impaired (Nb and Hp) compared with the young mice. Immunofluorescent staining revealed that after Hp infection, the number of alternatively activated macrophages, which are induced by Th2 cytokines, was lower in the aged mice. On the other hand, the number of CD4(+) T cells recruited to the worm cysts was normal compared with the young mice. These results suggest that migration of CD4(+) T cells to the host-parasite interface is not affected by ageing. Alterations in Th2 immune responses in aged mice might be due to inappropriate or insufficient activation of CD4(+) T cells in the submucosa.

Prevalence of intestinal parasite infections and associated clinical symptoms among patients with end-stage renal disease undergoing hemodialysis.

PURPOSE: Intestinal parasitic infections (IPIs) can result in high morbidity and mortality, particularly in immunocompromised patients. Infectious diseases are among the main causes of death in end-stage renal disease (ESRD) patients due to their impaired immune systems. The aim of this study was to determine the prevalence IPIs and their associated symptoms in ESRD patients. METHODS: In this case-control study, the fecal samples of 78 ESRD patients undergoing hemodialysis and 140 controls without any kidney problems were analyzed for intestinal parasites using direct-smear, formol-ether and modified Ziehl-Neelsen staining techniques. RESULTS: The difference in the prevalence of IPIs between ESRD patients (30.7 %) and the control group (10.7 %) was significant (OR = 3.7; 95 % CI = 1.8-7.61; P < 0.001). Blastocystis (14.1 %) and Cryptosporidium spp.(11.5 %) were the most common IPIs detected in ESRD patients, and the presence of Cryptosporidium spp. was significantly associated with diarrhea in ESRD patients (OR = 16; 95 % CI = 1.54-166.05; P < 0.05). Leukocytosis, diarrhea, weight loss, nausea/vomiting and bloating were also significantly higher in the hemodialysis group when compared with the control group. CONCLUSION: The current study revealed a high prevalence of intestinal parasites and related clinical symptoms in ESRD patients undergoing hemodialysis. Since hemodialysis patients are immunocompromised and intestinal parasites can cause serious clinical complications, we suggest that stool examination for intestinal parasites, with an emphasis on detection of Cryptosporidium spp. and Blastocystis, should be incorporated into the routine clinical care for these patients. Measures for preventing the acquisition of IPIs are also recommended.

Contribution of IL-33-activated type II innate lymphoid cells to pulmonary eosinophilia in intestinal nematode-infected mice.

When animals are infected with helminthic parasites, resistant hosts show type II helper T immune responses to expel worms. Recently, natural helper (NH) cells or nuocytes, newly identified type II innate lymphoid cells, are shown to express ST2 (IL-33 receptor) and produce IL-5 and IL-13 when stimulated with IL-33. Here we show the relevant roles of endogenous IL-33 for Strongyloides venezuelensis infection-induced lung eosinophilic inflammation by using Il33(-/-) mice. Alveolar epithelial type II cells (ATII) express IL-33 in their nucleus. Infection with S. venezuelensis or intranasal administration of chitin increases in the number of ATII cells and the level of IL-33. S. venezuelensis infection induces pulmonary accumulation of NH cells, which, after being stimulated with IL-33, proliferate and produce IL-5 and IL-13. Furthermore, S. venezuelensis infected Rag2(-/-) mice increase the number of ATII cells, NH cells, and eosinophils and the expression of IL-33 in their lungs. Finally, IL-33-stimulated NH cells induce lung eosinophilic inflammation and might aid to expel infected worms in the lungs.

Sex-determined susceptibility and differential MUC2 mRNA expression during the course of murine intestinal eimeriosis.

Parasitic diseases differ in prevalence, course, and severity between males and females. The study was designed to compare males with females for the susceptibility to Eimeria papillata infection as well as the expression of the mucin gene, MUC2. Oocysts output was detected to be more in the feces of male mice (3.5 × 10(4) ± 4000 oocysts/g feces) than in females (2 × 10(4) ± 2000 oocysts/g feces). In addition, infected males showed a significant higher number of meronts, gamonts, and developing oocysts compared to infected female mice. Moreover, E. papillata induced a marked goblet cell hypoplasia where the jejuna of infected male mice contained lower numbers of goblet cells per ten villus-crypt units compared to infected females. Also, the expression of MUC2 mRNA is found to be more expressed in infected females than males. In addition, testosterone, nitric oxide, and inducible nitric oxide synthase activities were found to be higher in infected male mice than in infected females. In general, male Swiss albino mice have been shown to be relatively more susceptible to infection with E. papilaata when compared with female mice.

Prevalence of Schistosomes and Soil-Transmitted Helminths and Morbidity Associated with Schistosomiasis among Adult Population in Lake Victoria Basin, Tanzania.

The objective of this study was to carry out a community survey on schistosomiais and soil-transmitted helminth (STH) infections in order to suggest feasible and effective intervention strategies in Lake Victoria basin, Tanzania. A total of 37 communities selected from 23 districts of the 4 regions in the Lake Victoria basin of Tanzania were involved in the study. From each of the selected locality, 50 adult community members, 25 males and 25 females, were recruited for the study. Each study participant was requested to submit stool and urine specimens. From each stool specimen, duplicate Kato-Katz thick smears were prepared and microscopically examined for Schistosoma mansoni and STH eggs. Urine specimens were processed by the filtration technique and microscopically examined for Schistosoma haematobium eggs. Ultrasound examination for morbidity due to schistosomiasis was performed. Mass treatment was done using praziquantel and albendazole for schistosome and STHs infections, respectively. Out of 1,606 adults who provided stool specimens, 199 (12.4%) were positive for S. mansoni, 349 (21.7%) for hookworms, 133 (8.3%) for Ascaris lumbricoides, and 33 (2.0%) for Trichuris trichiura. Out of 1,400 participants who provided urine specimens, 25 (1.8%) were positive for S. haematobium eggs. Because of the co-endemicity of these afflictions and their impact on vulnerable population groups, the helminthiasis could be simultaneously treated with 2 drugs, praziquantel for schistosomiasis and albendazole for STHs.

Intestinal capillariasis in the 21st century: clinical presentations and role of endoscopy and imaging.

BACKGROUND: Intestinal capillariasis is one of the common causes of malabsorption in the East. Reports emphasizing the roles of clinical, endoscopic and radiologic findings of intestinal capillariasis are limited. METHODS: Retrospective review of medical records of 26 patients diagnosed with intestinal capillariasis at Siriraj Hospital, Bangkok, Thailand between 2001- 2013. RESULTS: Clinical manifestations were chronic watery diarrhea (93%), chronic abdominal pain (70%), significant weight loss (92%), hypoalbuminemia (100%; 85% lower than 2.0 g/dL), and anemia (50%). The median duration of symptoms was 5.5 months (1-60 months). Parasites were found in stool in 15 patients (57%). In patients whose stool tests were initially negative, parasites were discovered in tissue biopsy from endoscopy in 1 from 10 esophagogastroduodenoscopies (EGD), 0 from 7 colonoscopies, 3 from 5 push enteroscopies, and 3 from 5 balloon-assisted enteroscopies (BAE). Endoscopic findings included scalloping appearance, mucosal cracking, and redness of mucosa. These endoscopic findings affected mostly at jejunum and proximal ileum. They were similar to celiac disease except duodenal involvement which is uncommon in capillariasis. Three patients underwent video capsule endoscopy (VCE) and typical abnormal findings were observed in all patients. Small bowel barium study showed fold thickening, fold effacement, and increased luminal fluid in 80% of patients, mainly seen at distal jejunum and ileum. CT findings were long segment wall thickening, enhanced wall, and fold effacement. Treatment with either albendazole or ivermectin cured all patients with most responding within 2 months. CONCLUSIONS: In endemic area, intestinal capillariasis should be considered if patients develop chronic watery diarrhea accompanied by significant weight loss and severe hypoalbuminemia. Stool examination had quite low sensitivities in making diagnosis in our study. Deep enteroscopy with biopsy guided by imaging or VCE may improve diagnostic yield. Empirical therapy may also be justifiable due to the very good response rate and less side effects.

IL-22 mediates host defense against an intestinal intracellular parasite in the absence of IFN-γ at the cost of Th17-driven immunopathology.

The roles of Th1 and Th17 responses as mediators of host protection and pathology in the intestine are the subjects of intense research. In this study, we investigated a model of intestinal inflammation driven by the intracellular apicomplexan parasite Eimeria falciformis. Although IFN-γ was the predominant cytokine during E. falciformis infection in wild-type mice, it was found to be dispensable for host defense and the development of intestinal inflammation. E. falciformis-infected IFN-γR(-/-) and IFN-γ(-/-) mice developed dramatically exacerbated body weight loss and intestinal pathology, but they surprisingly harbored fewer parasites. This was associated with a striking increase in parasite-specific IL-17A and IL-22 production in the mesenteric lymph nodes and intestine. CD4(+) T cells were found to be the source of IL-17A and IL-22, which drove the recruitment of neutrophils and increased tissue expression of anti-microbial peptides (RegIIIß, RegIIIγ) and matrix metalloproteinase 9. Concurrent neutralization of IL-17A and IL-22 in E. falciformis-infected IFN-γR(-/-) mice resulted in a reduction in infection-induced body weight loss and inflammation and significantly increased parasite shedding. In contrast, neutralization of IL-22 alone was sufficient to increase parasite burden, but it had no effect on body weight loss. Treatment of an E. falciformis-infected intestinal epithelial cell line with IFN-γ, IL-17A, or IL-22 significantly reduced parasite development in vitro. Taken together, to our knowledge these data demonstrate for the first time an antiparasite effect of IL-22 during an intestinal infection, and they suggest that IL-17A and IL-22 have redundant roles in driving intestinal pathology in the absence of IFN-γ signaling.

Insights into regulatory molecules of intestinal epithelial cell turnover during experimental infection by Heterophyes heterophyes.

Heterophyiasis is an intestinal disease that remains endemic in many parts of the world, particularly the Nile Delta of Egypt and Southeast Asia, yet the populations at risk of infection expand throughout the world. The main histopathological feature of infection is villous atrophy, but the underlying factors are not well understood. Apoptosis of the villous epithelial cells was previously reported to be enhanced during intestinal parasitic infections; however, the role of Heterophyes heterophyes on enterocyte apoptosis was to be explored. Therefore, intestinal sections from mice experimentally infected with H. heterophyes were studied histopathologically and immunohistochemically for caspase-3 and NF-κB and compared to non-infected control mice. Atrophic villi covered by poorly differentiated epithelial cells were observed in the 2nd week post-infection. Also, we noted marked hyperplasia of the intestinal crypts with abundant inflammatory cellular infiltrate in the lamina propria, as well as apoptosis of cells lining the intestinal villi. Both caspase-3 and NF-κB showed positive staining in the intestinal epithelial cells with varying grades of intensity over the length of infection. Caspase-3 expression rose at the 2nd week p.i. then decreased over time, whereas NF-κB expression showed progressive increase throughout the weeks of infection. In conclusion, caspase-3 activation may be an important factor in the apoptotic pathway in early heterophyiasis, and, on the other hand, NF-κB seems to play a role in protecting the intestinal cells from excessive apoptosis. These observations may help open new avenues for tissue protective therapies that avoid or control the deleterious processes of apoptosis in various inflammatory conditions.

A rat model to study Blastocytis subtype 1 infections.

Blastocytis sp. is the most common enteric protozoan in human, but its pathogenesis is still unclear. To study the infectious effects of Blastocytis sp. on tissue damage, we orally challenged the Sprague Dawley (SD) rats with different doses of Blastocytis subtype1 (ST1) and examined the histological changes. We found that there was no difference of disease incidence among the Blastocytis ST1-infected groups challenged with different doses of the protozoan. Histological results showed that the lamina propria was infected by Blastocytis ST1 in the vacuolar form, along with the mucus membrane slough and inflammatory cell infiltration into the lamina propria. Compared to the uninfected group, the histological scores were significantly higher in the infected groups. However, groups infected with various doses of Blastocystis ST1 showed no difference in terms of histological scores. In conclusion, this study indicates that the SD rats can be easily infected with Blastocytis ST1 even with low dose of cysts, and the histopathological effects of the infection in the intestine of the infected rats show individual differences.

Redundant and pathogenic roles for IL-22 in mycobacterial, protozoan, and helminth infections.

IL-22 is a member of the IL-10 cytokine family and signals through a heterodimeric receptor composed of the common IL-10R2 subunit and the IL-22R subunit. IL-10 and IL-22 both activate the STAT3 signaling pathway; however, in contrast to IL-10, relatively little is known about IL-22 in the host response to infection. In this study, using IL-22(-/-) mice, neutralizing Abs to IL-22, or both, we show that IL-22 is dispensable for the development of immunity to the opportunistic pathogens Toxoplasma gondii and Mycobacterium avium when administered via the i.p. or i.v. route, respectively. IL-22 also played little to no role in aerosol infections with Mycobacterium tuberculosis and in granuloma formation and hepatic fibrosis following chronic percutaneous infections with the helminth parasite Schistosoma mansoni. A marked pathogenic role for IL-22 was, however, identified in toxoplasmosis when infections were established by the natural oral route. Anti-IL-22 Ab-treated mice developed significantly less intestinal pathology than control Ab-treated mice even though both groups displayed similar parasite burdens. The decreased gut pathology was associated with reduced IL-17A, IL-17F, TNF-alpha, and IFN-gamma expression. In contrast to the prior observations of IL-22 protective effects in the gut, these distinct findings with oral T. gondii infection demonstrate that IL-22 also has the potential to contribute to pathogenic inflammation in the intestine. The IL-22 pathway has emerged as a possible target for control of inflammation in certain autoimmune diseases. Our findings suggest that few if any infectious complications would be expected with the suppression of IL-22 signaling.

Intestinal paragonimiasis with colonic ulcer and hematochezia in an elderly Taiwanese woman.

A 94-year-old female with end-stage renal disease presents with fever, fatigue, and hematochezia. She had previously resided in Hunan Province, China, and Myanmar, and she immigrated to Taiwan 30 years ago. Colonoscopy revealed a colonic ulcer. Biopsy of the colonic ulcer showed ulceration of the colonic mucosa, and many Paragonimus westermani-like eggs were noted. Serum IgG antibody levels showed strong reactivity with P. westermani excretory-secretory antigens by ELISA. Intestinal paragonimiasis was thus diagnosed according to the morphology of the eggs and serologic finding. After treatment with praziquantel, hematochezia resolved. The present case illustrates the extreme manifestations encountered in severe intestinal paragonimiasis.

An indigenous case of intestinal capillariasis with protein-losing enteropathy in Korea.

We encountered an indigenous case of intestinal capillariasis with protein-losing enteropathy in the Republic of Korea. A 37-year-old man, residing in Sacheon-si, Gyeongsangnam-do, admitted to the Gyeongsang National University Hospital (GNUH) due to long-lasting diarrhea, abdominal pain, anasarca, and weight loss. He recalled that he frequently ate raw fish, especially the common blackish goby (Acanthogobius flavimanus) and has never been abroad. Under the suspicion of protein-losing enteropathy, he received various kinds of medical examinations, and was diagnosed as intestinal capillariasis based on characteristic sectional findings of nematode worms in the biopsied small intestine. Adults, juvenile worms, and eggs were also detected in the diarrheic stools collected before and after medication. The clinical symptoms became much better after treatment with albendazole 400 mg daily for 3 days, and all findings were in normal range in laboratory examinations performed after 1 month. The present study is the 6th Korean case of intestinal capillariasis and the 3rd indigenous one in the Republic of Korea.