West Nile (WN) virus, a mosquito-transmitted virus native to Africa, Asia, and Europe, was isolated from two species of mosquitoes, Culex pipiens and Aedes vexans, and from brain tissues of 28 American crows, Corvus brachyrhynchos, and one Cooper's hawk, Accipiter cooperii, in Connecticut. A portion of the genome of virus isolates from four different hosts was sequenced and analyzed by comparative phylogenetic analysis. Our isolates from Connecticut were similar to one another and most closely related to two WN isolates from Romania (2.8 and 3.6 percent difference). If established in North America, WN virus will likely have severe effects on human health and on the health of populations of birds.
See editorial on page 1589.Background~Aims: Infectious agents have long been suspected of playing a role in the initiation of Crohn's disease. The objective of this study was to search for likely microbial agents in diseased tissues using immunocytochemical techniques. Methods: Intestines and mesenteric lymph node specimens of 21 patients from two French families with a high frequency of Crohn's disease and from Connecticut were studied. The microbial agents searched for included Bacteroides vulgatus, Borrelia burgdorferi, Escherichia coil, Listeria monocytogenes, Streptococcus spp., bovine viral diarrhea virus, influenza A virus, measles virus, parainfluenza virus, and respiratory syncytial virus. Results: Seventy-five percent of the patients with Crohn's disease (12 of 16) were positively labeled with the antibody to Listeria. Macrophages and giant cells immunolabeled for this antigen were distributed underneath ulcers, along fissures, around abscesses, within the lamina propria, in granulomas, and in the germinal centers of mesenteric lymph nodes. In addition, 57% (12 of 21) of the cases contained the E. coil antigen, and 44% (7 of 16) contained the streptococcal antigen. The immunolabeling for the latter two agents also occurred within macrophages and giant cells, distributed in a pattern similar to that of Listeria antigen. Conclusions: The results suggest that Listeria spp., E. coil, and streptococci, but not measles virus, play a role in the pathogenesis of Crohn's disease.Abbreviations used in this paper: BVDV, bovine viral diarrhea virus; RSV, respiratory syncytial virus,
Research into Crohn's disease has recently been focused on the genetics of the patient, the gastrointestinal flora, the gut epithelium and mucosal immune responses. For over 60 years pathologists have reported that the fundamental alteration in Crohn's disease occurs in regional lymphatics of the intestine--the disease is a lymphocytic and granulomatous lymphangitis. At an earlier time, experimental sclerosis of regional intestinal lymphatics of the pig produced a chronic segmental enteritis with many features of Crohn's disease, including lymphocytic and granulomatous lymphangitis of the bowel wall and enteroenteric and enterocutaneous fistulas. In Crohn's disease, differences in the anatomic distribution of vasa recta appear to explain long-segment disease of the ileum and short-segment disease of the more proximal intestine. A variety of bacteria and viruses cause lymphangitis, suggesting that microorganisms may be at the centre of the basic changes in Crohn's disease. Dietary antigens and lipids are worthy of consideration as well. Now that antibodies to label lymphatics are available, attention should be directed at defining the initial damage to lymphatic endothelium and agents that might be responsible.
Chronic intractable diarrhea accompanied by hemorrhage occurs in dogs infrequently and in the past has been diagnosed as hemorrhagic gastroenteritis, hemorrhagic coljtiss. 1 1 9 30 or ulcerative colitisl3. Although references to colitis occur in clinical texts243 40 no descriptions of colitis in dogs were found in pathology textsly. 2 0 9 3 2 , 42. The condition herein reported appears to be a specific clinicopathologic entity which has been mentioned briefly in clinical papers13, but for which there is no detailed clinical or pathological description.
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