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PubMed1996

Two pharyngodonid nematodes, Alaeuris mexicana n. sp. and Ozolaimus ctenosauri, from the iguanid lizard Ctenosaura pectinata from Nayarit, Mexico.

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.

Animals↗
PubMedDate not supplied

Immunoepidemiology of intestinal helminth infections. 4. Immunopathology in trichuriasis: lessons from the mouse model.

The severity and consequences of human Trichuris infection vary widely. This may reflect differences in immune response. T. muris is a natural parasite of mice which provides a close, well defined, easily manipulated model for otherwise uninvestigatable aspects of this response. Normal mice reject the parasite in 3 weeks, but mice subjected to transient immunosuppression around the time of infection develop a persistent caecal infection. Sequential histopathological studies have shown that infected, normal mice develop a marked intraepithelial, mucosal, 'globule leucocyte' response, accompanied by low-level lymphocytic and histiocytic responses in the lamina propria. The reaction is maximal at 3 weeks and declines towards normal after rejection. Infected, immunosuppressed mice show a slower response with, by weeks 4 and 5, fewer 'globule leucocytes', but a chronic colitis comprising heavy, mixed, mucosal and submucosal inflammation and crypt damage accompanied by persistent parasite infection. The 'globule leucocyte' has been characterized by cytochemistry and electron microscopy as having a mast cell origin. This study, with other evidence, suggests that the replacement of a Th2 (allergic) T helper cell response by a Th1 (cell-mediated) response may result in increased severity and persistence of colitis in response to Trichuris infection.

Animals↗
PubMedDate not supplied

Septata intestinalis N. G., N. Sp., an intestinal microsporidian associated with chronic diarrhea and dissemination in AIDS patients.

Intestinal microsporidiosis in patients diagnosed with acquired immunodeficiency syndrome (AIDS) and having chronic diarrhea was first reported in 1985 and the associated microsporidian was named Enterocytozoon bieneusi. The intracellular developmental cycle of E. bieneusi in enterocytes has been demonstrated and many cases have been reported worldwide. This report presents the life cycle of a second intestinal microsporidian, associated with the same symptoms, in five AIDS patients. This new microsporidian also infects enterocytes but its pathology and morphology differ from that of E. bieneusi. It involves lamina propria macrophages, fibroblasts, and endothelial cells and can disseminate to infect other parts of the body, e.g. the kidney and gall bladder. The parasite cycle includes development of rounded uninucleate and elongated bi- or tetranucleate cells without the formation of plasmodial stages. Sporogony is similar to the more typical development of microsporidia with sporoblast morphogenesis occurring after the last cell division. The development of cells within chambers of a septate, honeycomb-like, parasite-secreted fibrillar network and surrounded by a parasitophorous vacuole, however, is unique to this microsporidian, justifying the establishment of a new genus and species, Septata intestinalis n. g., n. sp.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

The need for three stool specimens in routine laboratory examinations for intestinal parasites.

This study was designed to test whether three sequential stool specimens are necessary for reliable detection of intestinal parasites in routine laboratory examinations. There were 175 patients in whom a single species of intestinal parasite or ova was identified on at least one occasion when three stool specimens were examined over a period of 14 days from the first recorded specimen. Examination of a first stool specimen detected parasites and/or ova in 102/175 patients (58.3%); examination of a second specimen identified an additional 36 positive patients (20.6%) and examination of a third specimen yielded a final 37 previously undetected patients (21.1%). These findings indicate that at least three stool specimens should be examined to confirm the presence of intestinal parasites. Even with such practice, it is not possible to guarantee that there is no infestation, but examination of fewer specimens would run a definite risk of false negative results.

Feces↗
PubMed1987

Capillostrongyloides Ancistri sp. n. (Nematoda: Capillariidae) a new pathogenic parasite of aquarium fishes in Europe.

A new nematode species, Capillostrongyloides ancistri sp. n., is described from the intestine of aquarium-reared catfish Ancistrus dolichopterus Kner in Czechoslovakia. This fish is of South American origin and, therefore, C. ancistri sp. n. has probably been brought into aquaria in Europe from there. The parasite is characterized mainly by the structure of the male caudal end (presence of two large postanal papillae and the cuticular bursa supported by two caudal lobes), the length of a spicule (0.258-0.297 mm), the presence of a non-spiny spicular sheath, shape of the female end, structure of the stichosome (23-30 stichocytes present), and the size of the eggs. The species appears to be highly pathogenic to aquarium-reared Ancistrus dolichopterus, causing death of these fish.

Animals↗
PubMed1984

Pathological changes and immunity associated with experimental Eimeria vermiformis infections in Mus musculus.

Pathological changes and immunity induced by Eimeria vermiformis (Ernst, Chobotar & Hammond, 1971) were studied in outbred Swiss mice inoculated with 5000, 10,000, 20,000, or 40,000 oocysts. Cross immunity to E. ferrisi was also studied. In the case of E. vermiformis, mortality was dose dependent; most deaths were observed in the intermediate-dose groups. Most deaths also correlated with peak oocyst output. Histopathologic changes consisted of an early neutrophil and mononuclear cell infiltration in the small intestine. Later, villus atrophy and crypt hyperplasia caused a decrease in the villus-crypt ratio. During the acute phase (8-10 days after inoculation), villus tips were eroded and parasites with necrotic debris filled the cryptal and intestinal lumina. Vacuolar changes were observed in epithelial cells of the small intestine. Neither parasites nor significant pathological changes were observed in extra-intestinal organs. Mice were totally immune to reinfection with E. vermiformis 30 and 105 days after inoculation. Cross immunity was not observed between E. vermiformis and E. ferrisi.

Animals↗
PubMed1994

Lead accumulation in Pomphorhynchus laevis and its host.

Adults of Pomphorhynchus laevis were collected from the intestines of 10 chubs (Leuciscus cephalus) from the river Ruhr near Bochum, Germany. The acanthocephalans and various tissues of the fish (muscle, liver, and intestine) were analyzed for lead with electrothermal atomic absorption spectrometry. The mean lead level in the parasite was 54 micrograms/g wet weight, which was 284 times more than in the host intestine, 771 times more than in host liver, and 2,700 times more than in host muscle. Thus, P. laevis may serve as a very sensitive bioindicator for the presence of biologically available lead in aquatic ecosystems.

Acanthocephala↗
PubMed2002

Paneth and intermediate cell hyperplasia induced in mice by helminth infections.

Hyperplasia of Paneth and intermediate cells is a recently described component of the response of the small intestine of mice to infection with the nematode Trichinella spiralis. To investigate whether this hyperplasia is parasite specific or represents a generic intestinal response to infection, mice were infected with T. spiralis, Nippostrongylus brasiliensis, Heligmosomoides polygyrus or Schistosoma mansoni and tissue samples taken at various time-points post-infection to determine Paneth and intermediate cell numbers. All infections induced Paneth and intermediate cell hyperplasia, but the patterns of response varied between the parasite species concerned, reflecting differences in their relationships with the host. Increases in the numbers of these cells appeared to correlate with known patterns of T-helper-2 immune responses.

Animals↗
PubMed2002

Status of intestinal parasites infection among primary school children in Kampongcham, Cambodia.

A survey was made to find the extent of intestinal parasite infection in Kampongcham, Cambodia in February 2002. A total of 251 fecal specimens were collected from Tonlebat primary school children and examined by formalin-ether sedimentation technique. The overall infection rate of intestinal parasite was 54.2% (males, 57.3%; females, 50.8%). The infection rate of intestinal helminths by the species were as follows: Ascaris lumbricoides 26.3%, Echinostoma sp. 15.6%, hookworm 6.4%, Opisthorchis sp. 4.0%, Rhabditis sp. 2.4%, and Trichuris trichiura 0.4%. The infection rate of intestinal protozoa were as follows: E. coli 7.6%, G. lamblia 3.2%, I. butschlii 3.2%, and E. histolytica 0.8%. More than two different kinds of parasites were found in 16.7% of the stool samples. All the children infected were treated with albendazole, praziquantel and metronidazole according to parasite species. The results showed that intestinal parasites are highly endemic in this area.

Age Factors↗
PubMed1989

Phagicola angrense (Digenea: Heterophyidae) as a cause of enteritis in a raccoon (Procyon lotor).

Numerous Phagicola angrense were associated with enteritis in a single male juvenile raccoon (Procyon lotor) live-trapped on Parramore Island, Virginia (USA). The raccoon was weak, ataxic and had melenic soft feces. The carcass was emaciated, pale and had ascites. Mesenteric vessels appeared prominent and the stomach and the intestines contained fetid bloody material. The small intestinal mucosa contained three locally extensive sites of necrosis. Histopathologically, there were numerous small digeneans both attached to the mucosa and free within the lumen. Digeneans were usually found deep within the crypts where the epithelium was markedly attenuated and devoid of epithelial cells at the point of parasite attachment. In the lamina propria there were areas of acute hemorrhage and infiltration with plasma cells and eosinophils. This appears to be the first record of severe enteritis in the raccoon caused by this digenean.

Animals↗
PubMed1996

Pathobiology associated with the spiruroid nematodes Camallanus oxycephalus and Spinitectus carolini in the intestine of green sunfish, Lepomis cyanellus.

The histopathology induced by Camallanus oxycephalus and Spinitectus carolini in the intestine of green sunfish Lepomis cyanellus was examined. At what is assumed to be more recent attachment sites, penetration of C. oxycephalus was restricted to the mucosal layer, causing complete destruction of the columnar epithelium. At what appeared to be older attachment sites, the parasite penetrated deep into the intestinal wall, even to the circular muscle layer. At these sites of attachment, there were flask-shaped ulcers in the mucosal and submucosal layers. Surrounding the ulcers, there was granulomatous tissue, with extensive fibrosis at the surface; the fibrosis probably reduced the loss of body fluids and blood cells from the intestinal wall. The number of goblet cells in the posterior end of the intestine increased significantly, from 92.6 cells/mm in uninfected fish to 168.4 cells/mm in fish infected with more than 5 C. oxycephalus. Adult S. carolini also causes severe damage to the intestinal wall of green sunfish. Parasite penetration was not limited to the mucosal layer. Mature worms were observed invading both the muscular and serosal layers. Penetration by the parasite was usually associated with the local loss of columnar epithelium and infiltration by lymphocytes and granulocytic leukocytes. Fibrosis in the mucosal layer was commonly observed. There was goblet cell hyperplasia in the anterior portion of the intestine, with numbers of goblet cells increasing from 64.4 cells/mm in uninfected fish to 95.0 cells/mm in heavily infected fish.

Animals↗
PubMed1992

T lymphocyte dependent enteropathy in murine Trichinella spiralis infection.

Mice infected with Trichinella spiralis developed significant enteropathy, comprising villus atrophy, crypt hyperplasia, goblet cell hyperplasia and a decrease in intra-epithelial lymphocyte numbers by 10 days post-infection, when most of the parasites had been expelled from the gut. However, worm expulsion was prevented by treatment with cyclosporin A and, despite a continued parasite burden, cyclosporin A treated animals had no villus atrophy or changes in inflammatory cell numbers. These results confirm that the expulsion of T. spiralis from the mouse gut is accompanied by a significant intestinal lesion and that both of these phenomena are T-cell mediated.

Animals↗
PubMed1989

Trichostrongylus colubriformis: epithelial cell kinetics in the small intestine of infected rabbits.

Epithelial cell kinetic parameters were compared in intestines of control and Trichostrongylus colubriformis infected rabbits using a microdissection and metaphase accumulation technique in regions of gut with heavy (proximal site) and small (distal site) burdens of worms. In control animals, the cell production rates were respectively 4.3 cells/crypt/hr in the proximal region and 3.7 cells/crypt/hr in the distal one; and the influx of cells onto villi were respectively 67.5 cells/hr and 37.4 cells/hr. In the parasitized rabbits, in the main site of infection, a fourfold increase was recorded in the cell proliferation rate and in the influx of cells onto villi. In the region distal to the main site of infection, the same parameters were twice the control values, although only a low number of T. colubriformis were recovered from this part of gut. These large modifications in the epithelial renewal probably underlies the morphological and enzymological changes previously described in both parts of the T. colubriformis infected gut.

Animals↗
PubMed1995

Role of T lymphocytes in secretory response to an enteric nematode parasite. Studies in athymic rats.

Athymic (nude) rats have been used to assess the role of thymus-dependent T cells in the control of the intestinal response following infection with the enteric parasite, Nippostrongylus brasiliensis. Tissues from infected rats were excised on days 4, 7, 10, and 21 postinfection (p-i) for physiological and morphological studies; uninfected (day 0) rats served as controls. In response to the worm burden, jejunal tissues displayed a secretory response, indicated by an elevated baseline short-circuit current (Isc) on days 7 and 10 p-i, and were more responsive to histamine than control tissues. Despite this enhanced secretory response, approximately 35% of the worm burden was still present on day 21 p-i (compared with expulsion of > 95% by day 14 p-i in normal rats). Mast cell activation and hyperplasia, increased goblet cell (implying increased mucus synthesis) and intraepithelial leukocyte numbers, and abnormalities in Isc responses after electrical stimulation of enteric nerves were identified following infection. These events in nude rats were attenuated or delayed in onset as compared with conventional immunocompetent rats. Our results support the postulate that thymus-dependent T cells regulate the timing and/or nature of the mucosal response to enteric parasitic infections. However, ion secretion was not altered in the absence of T cells and, therefore, is more likely to be a consequence of mast cell activation.

Analysis of Variance↗
PubMed2003

Redescription of Hammondia hammondi and its differentiation from Toxoplasma gondii.

Hammondia hammondi is a protozoan parasite that, until 1975, was misidentified as Toxoplasma gondii. Recently, the validity of H. hammondi has been questioned. In this article, the authors redescribe the parasite and its life cycle, provide accession numbers to its specimens deposited in a museum, and distinguish it structurally and biologically from T. gondii. Hammondia hammondi was found to be structurally, biologically, and molecularly different from T. gondii.

Animals↗
PubMed2003

Prevalence of zoonotic important parasites in the red fox (Vulpes vulpes) in Great Britain.

A national necropsy survey of red foxes was carried out across Great Britain to record Echinococcus, Trichinella and Toxoplasma. The survey did not record directly, or indirectly using coproantigen/PCR tests, evidence for the presence of Echinococcus multilocularis in 588 animals, although E. granulosus was suspected in six animals. Parasitological evidence for Trichinella spp. could not be found in 587 fox muscle digests, and a specific PCR test also failed to detect Toxoplasma in a sub-set of 61 random fox tongue biopsies. The upper 95% confidence interval for the above parasites was 0.60% (E. multilocularis), 0.60% (Trichinella spp.) and 5.6% (Toxoplasma). The commonest gut parasites were the hookworm Uncinaria stenocephala (41.3%) and the ascarid Toxocara canis (61.6%). This study also reports the second occurrence of Trichuris vulpis in Great Britain.

Animals↗
PubMed2001

Abomasal and small intestinal nematodes from captive gazelles in Spain.

The abomasal and small intestinal helminth fauna of three species of captive gazelles (Gazella dama mhorr, G. cuvieri and G. dorcas neglecta) kept in captivity in Almería (southeast Spain) have been studied, and the following species were identified: Nematodirus spathiger, N. filicollis, N. helvetianus, Camelostrongylus mentulatus, Trichostrongylus vitrinus, T. probolurus, T. colubriformis, Ostertagia ostertagi, O. harrisi, Teladorsagia (Ostertagia) circumcincta, and T. (Ostertagia) davtiani. Camelostrongylus mentulatus and N. spathiger were the most prevalent and abundant parasites. Ostertagia ostertagi, O. harrisi, N. helvetianus, and T. (Ostertagia) davtiani were identified for the first time in the genus Gazella. In addition, O. harrisi and Trichostrongylus probolurus are new records for Spain.

Abomasum↗