An Asymptomatic Case of Diphylobrothrium Latum in the United States

Background: Spirochaetosis in the colon is defined by histological observation of spirochaetal strains of Brachyspira (pilosicoli or aalbogi) adherent to colonic epithelium, usually seen in biopsies taken for investigation of nebulous gastrointestinal (GI) symptoms.Histology is said to be normal in the majority of these cases 1 .However, the pathology described is that of overt neutrophil infiltration, not subtle changes in innate inflammation.We have previously reported that spirochaetosis is associated with irritable bowel syndrome (IBS) 2 and have noted in functional disorders that pathology is linked to innate immunity 3 .Lymphoid follicles are noted to be associated with persistent diarrhea 4 .The aim of this study was to identify subtle pathologies in colonic spirochaetosis (CS).Methods: Colonoscopy with biopsies was performed in 745 subjects (aged 19-70 years, mean age 51 years, 43% male) and biopsies taken from the ileum and 4 sites in the colon from a random population sample in Stockholm, Sweden.Ethical approval was obtained from Huddinge University Hospital.A completed validated questionnaire of GI symptoms was taken.Spirochaetosis was identified in biopsies by immunohistochemistry.A matched case and control study of histology was performed, noting eosinophil counts, lymphoid aggregates and lymphoid follicles in biopsies.A comparison of immunohistochemistry and standard H&E identification of CS was undertaken in all 16 cases from the study and 16 age and sex matched controls.For the numeric scores of cells, the test is the Wilcoxon Signed Ranks test and for the yes/no variables McNemars test for paired proportions.Results: No statistically significant difference for any single symptom was found, however, IBS (Rome III) was a significant finding in cases compared to controls (p = 0.01).Eosinophils were increased in colon biopsies in CS, in the sigmoid colon, p = 0.001 and in the rectum, p= 0.0005.Also the presence of subepithelial eosinophil clusters were significant, p = 0.05.Lymphoid follicles at any site were present in 13/16 cases, nil were present in controls, p= 0.0003.CS was absent in rectal biopsies from 2/16 cases, but present in all other colonic sites on immunohistochemistry. Conclusions: Subtle histopathology is present in CS, with increased eosinophils, subepithelial eosinophil clusters and the presence of lymphoid follicles.These features should alert the pathologist to look for CS.We would recommend a sigmoid and rectal biopsy for diagnosis as CS is not always present in the rectum.1.