1/4. cyclosporiasis: clinical and histopathologic correlates.Although the histopathologic changes associated with cyclospora cayetanensis infection have been previously described, the histopathology and the appearance of various life cycle stages have not been correlated with severity, stage, and duration of clinical disease. We report a prospective clinical investigation of disease characteristics and histopathologic findings in three otherwise healthy, immunocompetent patients with symptomatic C. cayetanensis infection, the duration of which ranged from 6 to 60 days. Varying degrees of gross and microscopic gastrointestinal inflammation were seen before treatment. An electron-dense phospholipid membrane/myelin-like material was variably present both before and after treatment. The greatest amount of myelin-like material was seen in the patient with prolonged disease. The results of our study suggest that inflammatory changes associated with C. cayetanensis infection may persist beyond parasite eradication. It is intriguing to speculate that the myelin-like material is a marker for persistent inflammation, but further study and confirmation are needed.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
2/4. Intractable diarrhea of infancy due to intestinal coccidiosis.Intestinal coccidiosis in a 6-mo-old infant terminated fatally after 30 wk of continuous total parenteral nutrition, and proved refractory to treatment with antibiotics, hydrocortisone, and antimetabolic agents. Intestinal biopsies obtained at laparotomy revealed flattened mucosa infiltrated with coccidia at various stages of the parasites' life cycle. The course was characterized by severe diarrhea due to a cholera-like hypersecretion of intraluminal fluid. This case suggests that intestinal coccidiosis may be included among the small number of conditions responsible for authentic "intractable diarrhea of infancy."- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
3/4. Submicroscopic profile of isospora belli enteritis in a patient with acquired immune deficiency syndrome.Small bowel mucosal fragments from a human immunodeficiency virus-positive female patient with chronic diarrhea were investigated by transmission electron microscopy, and isospora belli enteritis was documented. The submicroscopic profile was characterized by a moderate abnormality of mucosal architecture with reduction in height of villi and hypertrophy of crypts. Stages of both asexual (trophozoite, schizont and merozoite) and sexual (macrogametocyte) phases of the life cycle of the parasite were identified in the epithelium, always enclosed within a parasitophorous vacuole. Moreover, the presence of occasional extracellular merozoites in the intestinal lumen and in the lamina propria near or within lymphatic vessels was documented. These findings expand the current knowledge of this parasite regarding its capacity to survive in an extracellular environment and document a possible mechanism by which extraintestinal infection can take place.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
4/4. light and electron microscopic identification of cyclospora species in the small intestine. Evidence of the presence of asexual life cycle in human host.This is the first case of cyclosporiasis in which the parasite was clearly demonstrated in a duodenal biopsy by light microscopy. Electron microscopy identified the stages of sporozoite, trophozoite, schizont, and merozoite. Although only asexual forms were identified in our case, the sexual cycle must have taken place in the human host, because oocysts were detected in stools of the patients. Therefore, it appears that cyclospora species require only a single host to complete its entire life cycle. Despite the heavy infection, only enterocytes were invaded. The lamina propria and submucosa were not involved. The morphology of cyclospora in the intestine is similar to that of isospora, but differs from that of cryptosporidium. The morphology of the oocyst of cyclospora resembles that of cryptosporidium, but differs from that of isospora. Thus, a combined study of both stool and intestinal biopsy should readily distinguish cyclospora from cryptosporidium and isospora.- - - - - - - - - - ranking = 6keywords = cycle (Clic here for more details about this article) |