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Title: THE PATHOGENESIS OF NECROTIC PROLIFERATIVE COLITIS IN SWINE IS LINKED TO WHIPWORM INDUCED SUPPRESSION OF MUCOSAL IMMUNITY TO RESIDENT BACTERIA

Author
item MANSFIELD LINDA
item URBAN JOSEPH F

Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: A number of infectious agents have been associated with the appearance of bloody diarrhea in young and growing pigs. Studies of this condition have been difficult because experimental infections with isolated organisms have not successfully reproduced the severity of the disease seen in the field. We have recently observed that pigs infected naturally with whipworm, Trichuris suis, consistently exhibit bloody diarrhea, but pigs are protected from disease if they are vaccinated against whipworm infection. We report here that pigs maintained in confinement on concrete floor pens exhibit severe diarrhea after experimental inoculation with whipworm eggs. In addition, this conditions is ameliorated by the strategic application of broad spectrum antibiotics. These studies link the onset and severity of mucohemorrhagic diarrhea in pigs to whipworm induce suppression of immunity to resident pathogenic bacteria. This observation will not only provide researchers with an excellent model to study this disease complex in swine, but will provide producers and veterinarians with information on control strategies to reduce the incidence and severity of mucohemorrhagic diarrhea in pigs. Further, many of the bacteria responsible for diarrhea in pigs also infect humans, therefore, control of infection will improve herd health and the safety of the food supply.

Technical Abstract: Mucohemorrhagic enteropathies of the intestinal tract of swine have complex and interrelated etiologies of largely unknown pathogenesis. Pigs inoculated with 2,500 embryonated Trichuris suis (whipworm) eggs exhibited diarrhea, intestinal adenomatosis associated with the intracellular Ileal symbiont intracellularis bacteria, enlarged colonic lymphoglandular complexes (LGCs) containing numerous extracellular bacteria, eosinophils, lymphocytes, macrophages, and neutrophils, and at the site of worm attachment in the proximal colon, mucosal edema, inflammatory cell infiltration, and bacterial accumulation. Other pigs inoculated with T. suis and treated with antibiotics had pathologic lesions localized to the site of worm attachment, and histologically normal LGCs with no resident bacteria. The association between bacteria, lymphocytes and macrophages in the LGCs of pigs infected with T. suis suggests an antigen processing role for these structures in the colon. Further, the complex pathogenesis of necrotic proliferative colitis in pigs can be linked to worm induced suppression of mucosal immunity to resident bacteria.