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Schistosoma mansoni and S. haematobium infections in Egypt. I. Evaluation of techniques for recovery of worms and eggs at necropsy.

Four hundred consecutive autopsy cases were examined in Cairo, Egypt. Sixty percent of cases had Schistosoma haematobium eggs in the tissues and 25% also were infected with S. mansoni. Only a quarter of S. haematobium infections were active, while nearly two-thirds of S. mansoni cases remained active. Adult S. haematobium and S. mansoni were effectively recovered from the mesenteric circulation by a combination of perfusion and dissection. Quantitative recovery from the genitourinary system was reasonably complete, although small numbers of worms were missed in the dissection of these organs.

Adolescent↗

Dietary fiber and giardiasis: dietary fiber reduces rate of intestinal infection by Giardia lamblia in the gerbil.

Gerbils were maintained on a low-fiber (5%) or a high-fiber (20%) diet in which the major fiber source was cellulose. Animals in the low-fiber diet group were significantly more likely to become infected when inoculated with 100 Giardia lamblia cysts than were animals in the high-fiber group. No differences were detected in gastrointestinal transit, gastric, and small intestinal luminal pH, or in duodenal mucus blanket acidic glycoprotein between animals in the high- and the low-fiber diet groups at the time of cyst inoculation. The fiber content of the diet after cyst inoculation determined the infection rate. These data suggest that the dietary fiber effect occurred during trophozoite colonization of the small intestine. When infected animals on the low-fiber diet were placed on the high-fiber diet for 24 hr, trophozoite clearing occurred in the lower small intestine. In the jejunum, the number of trophozoites attached to the mucosal surface decreased, while the number associated with luminal mucus increased. We conclude that the fiber-induced mucus secretion and the bulk movement of the insoluble fiber reduced the attachment of trophozoites to the intestinal mucosa, which decreased the probability of trophozoites establishing and sustaining colonization of the mucosa.

Animals↗

Intestinal cryptosporidiosis: pathophysiologic alterations and specific cellular and humoral immune responses in rnu/+ and rnu/rnu (athymic) rats.

In order to develop an experimental model of symptomatic cryptosporidiosis in an immunosuppressed mammal, we investigated the pathophysiology of infection with Cryptosporidium and the humoral and cellular host responses in rnu/rnu (athymic) rats and their heterozygous (rnu/+) littermates by challenging suckling rats with greater than or equal to 2.5 x 10(6) Cryptosporidium oocytes oro-gastrically. Normal and immunodeficient animals were followed for onset and duration of infection (fecal oocysts), physiologic consequences (diarrhea, impaired weight gain, brush-border enzyme activities), and immunologic response (both B- and T-lymphocyte-mediated). Homozygosity for the rnu gene was associated with protracted cryptosporidial infections; shedding for up to 52 days occurred, and delay in weight gain was noted in rnu/rnu-infected compared with rnu/rnu-uninfected rats (p less than 0.05). In contrast, cryptosporidial challenge of rnu/+ rats resulted in self-resolving infections, occasionally with transient diarrhea lasting four days or less occurring 10-15 days after oro-gastric challenge. The latter animals mounted a cell-mediated immune response to Cryptosporidium: three months after challenge, five of five rnu/+ rats demonstrated positive skin test responses to a subcutaneous 3.5 micrograms dose of cryptosporidial antigen. Further, sera from 6 rnu/+ rats taken two to three months after oro-gastric oocyst challenge exhibited specific anticryptosporidial immunoglobulin binding (A405 = 0.96), compared to that of seven uninfected rnu/+ controls (A405 = 0.09, P less than 0.02). Macromolecules of 150, 105, and 88 kD in the Cryptosporidium antigen preparation were bound by serum immunoglobulin from previously infected, recovered rnu/+ rats. Two brush-border enzymes (lactase and alkaline phosphatase) were markedly reduced in the ileum 8-10 days after oro-gastric challenge in rats with diarrhea and oocyst shedding. We find the rnu/rnu (athymic, nude) rat provides a useful model for study of prolonged cryptosporidial infection with impaired weight loss, brush-border enzyme alteration and intermittent diarrhea. These studies further suggest that a T-lymphocyte population is involved in recovery from Cryptosporidium infection and that this recovery is associated with both cellular and humoral immune responses to specific cryptosporidial antigenic macromolecules. This model should open further avenues for the study of the pathogenesis and protective immunity in cryptosporidial infection.

Animals↗

A case of intestinal capillariasis in the Republic of Korea.

In 1991, we observed a Korean man infected by Capillaria philippinensis who had no history of traveling in known endemic areas. He had year-long diarrhea with severe loss of body weight. He enjoyed hunting and fishing and eating raw meat of game animals and fish. An open full-thickness biopsy of the ileum showed flat mucosal surface and sections of the round worm, and fecal examination revealed numerous elliptical helminth eggs. The worms and eggs were consistent with features of C. philippinensis. He was treated with albendazole and was cured. This is the first known case of intestinal capillariasis in the Republic of Korea.

Adult↗

Intraepithelial lymphocytosis in architecturally preserved proximal small intestinal mucosa: an increasing diagnostic problem with a wide differential diagnosis.

CONTEXT: An increased intraepithelial lymphocyte density in an architecturally normal proximal small intestinal mucosal biopsy is a common finding facing surgical pathologists dealing with gastrointestinal biopsy specimens. Approximately 1% to 2% of all proximal small intestinal biopsies will show this change. It is increasingly recognized by surgical pathologists that gluten-sensitive enteropathy is an important cause of this pattern; however, gluten-sensitive enteropathy accounts for the minority of all cases. A wide variety of immunologic stimuli can raise intraepithelial lymphocyte numbers. Among the other common associations are enteric infection, autoimmune disease, drugs, and gastric Helicobacter infection. OBJECTIVE: To outline the causes of intraepithelial lymphocytosis, to highlight the importance and the difficulties faced in establishing gluten-sensitive enteropathy as the cause, and to aid the surgical pathologist in the routine sign out of these cases. DATA SOURCES: A review of the literature detailing the causes or associations of proximal small intestinal intraepithelial lymphocytosis is presented. CONCLUSIONS: Increased lymphocyte numbers in the epithelium of architecturally preserved proximal small intestinal biopsies is a morphologic feature associated with a broad differential diagnosis.

Autoimmune Diseases↗

Understanding intestinal spore-forming protozoa: cryptosporidia, microsporidia, isospora, and cyclospora.

OBJECTIVES: To summarize recent information about the "new" gastrointestinal protozoal pathogens (cryptosporidia, microsporidia, isospora, and cyclospora) and to help practicing clinicians integrate this information into their clinical databases by emphasizing the similarities among these organisms. DATA SOURCES: Relevant English-language articles published between 1988 and 1995 were identified through a MEDLINE search done using the names of the intestinal spore-forming protozoa. Articles cited in the bibliographies of these and other articles were searched manually. STUDY SELECTION: Studies that contained information on the history, taxonomy, life cycle, epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of the pathogens were reviewed. DATA EXTRACTION: Cryptosporidium parvum, Isospora belli, Cyclospora cayetanensis, Enterocytozoon bieneusi, and Septata intestinalis are intestinal spore-forming protozoa that cause intracellular infections, predominantly in the epithelial cells of the intestine. They are transmitted either by stool from person to person or through contaminated water or food by an infectious particle called a spore or oocyst. Asymptomatic infections occur; the most common symptom of infection is diarrhea. Infections have been associated with intestinal inflammation, disordered architecture (such as villus blunting), and abnormal function (for example, malabsorption). Mild to moderate, self-limited diarrhea is common in healthy persons, but patients with immune dysfunction can have severe intestinal injury and prolonged diarrhea. Diagnosis is made by a microscopic examination of the stool and the use of appropriate staining techniques. Effective antibiotic treatment for prolonged infection in immunocompromised patients is available for most of these infections. CONCLUSIONS: The intestinal spore-forming protozoa are four frequently identified gastrointestinal pathogens that have important similarities in epidemiology, disease pathogenesis, clinical manifestations, diagnosis, and treatment.

Animals↗

Endogenous development and pathogenicity of Eimeria angusta in the ruffed grouse, Bonasa umbellus.

Oocysts of Eimeria angusta were recovered from the cecum of a captive ruffed grouse which died of coccidial typhlitis. Five experimental passages were made in grouse over a 2-yr period. Prepatent period was 6.5-7.0 days; sporulation time at 22 C was 54-60 hr. Endogenous stages were not found in grouse killed 1 and 2 days after inoculation (DAI). A few immature schizonts were in cecal epithelium 4 DAI. Developing and mature schizonts, and undifferentiated gamonts were in cecal epithelium 5 DAI. Developing micro- and macrogamonts, but no oocysts, were present 6.5 DAI. Fibrinohemorrhagic typhlitis, associated with large numbers of gamonts and oocysts in the epithelium, was found 9 DAI. Cecal glands were hypertrophic and there was a heavy mixed inflammatory cell reaction. Diarrhea, depression and reduced feed intake occurred 7-10 DAI with most severe signs and greatest oocyst passage 8 or 9 DAI. Most infected birds lost weight 5-8 or 9 DAI, but none died.

Animals↗

Invasive entamoebae in pronghorn (Antilocapra americana) from Wyoming.

Trophozoites and cysts of an amoeba resembling Entamoeba bovis were recovered from soft stools of captive pronghorn fawns (Antilocapra americana). Chronic or intermittent diarrhea was observed in most individuals in two groups of hand-raised 1- to 8-mo-old pronghorns. Ileocecal lymph nodes were mildly to moderately enlarged. Microscopic lesions were characterized by lymphoid hyperplasia, focal necrosis and pyogranulomatous inflammation in lymph nodes and focal necrosis and diffuse nonsuppurative enteritis in ileum and cecum. In 12 of 17 fawns, trophic stages of amoebae were observed in the submucosa of the cecum and/or the cortex of the ileocecal lymph node. This is the first report of E. bovis-like organisms invading and causing pathological changes in the tissues of their host.

Amebiasis↗

Intestinal helminths of the granite spiny lizard (Sceloporus orcutti).

Examination of the intestinal tracts of 74 granite spiny lizards (Sceloporus orcutti) from Riverside County, California (USA) revealed infection with one cestode species Oochoristica scelopori (Anoplocephalidae) and one nematode species Spauligodon giganticus (Pharyngodonidae). Helminth prevalence was 24%. The presence of Oochoristica scelopori represents a new host record.

Animals↗

Chaunocephalosis in a wild population of Asian open-billed storks in Thailand.

The most common trematode collected from Asian open-billed storks (Anastomus oscitans) was Chaunocephalus ferox (80% prevalence). The trematode was paired in granulomas in the intestinal wall. Based on histological examination of these capsules, there was degeneration and necrosis of muscle cells in the tunica muscularis. Granulation tissue with hetrophil and lymphocyte infiltration appeared in the granulomas. Intestinal villi were shorter and wider in infected areas than in non-infected areas. Some intestinal glands were dilated. Storks with high intensity of C. ferox appeared ill. The death of storks infected with C. ferox may result from malnutrition due to the loss of absorptive function of the intestine and from the effect of granuloma formation which might interfere with the intestinal peristalsis.

Animals↗

Epizootic mortality of free-living green turtles, Chelonia mydas, due to coccidiosis.

At least 70 wild green sea turtles, Chelonia mydas, died in the Moreton Bay area of southeast Queensland, Australia over 6 wk in spring 1991. Based on the necropsy of 24 turtles, there was a severe enteritis or encephalitis associated with Caryospora cheloniae, a coccidial pathogen previously recorded only in farm-reared Ch. mydas hatchlings. Infection was characterized by the presence of coccidia in extra-intestinal lesions. Oocysts were observed to sporulate, after which sporozoites escaped into seawater to form a novel stellate configuration. We conclude that C. cheloniae is pathogenic for life stages other than hatchling Ch. mydas and that naturally-occurring coccidiosis is a significant disease of free-living Ch. mydas.

Animals↗

Cryptosporidiosis in a black bear in Virginia.

Cryptosporidiosis has not been previously reported in black bears in North America, either free-roaming or captive. However, oocysts have been documented in two captive Malayan sun bears (Helarctos malayanus) located in zoological parks in Taiwan. Developmental stages of Cryptosporidium parvum were observed in tissue sections from the small intestine of a black bear cub found dead in Virginia (USA).

Animals↗