Study of porcine intestinal adenomatosis

Abstract

Field cases of porcine intestinal adenomatosis (PIA), necrotic enteritis (KE) and regional ileitis (Rl) were studied. Adenomatous proliferation was present in the intestinal mucosa in all three conditions and the bacterium, Cambylobacter soutorum subspecies mucosalis. was recovered consistently from the lesions. The organism was free within the apical cytoplasm of the affected intestinal epithelial cells and was not surrounded by host-cell membranes. A marked immaturity of the parasitised epithelial cells was seen but no degenerative or inflammatory changes. Whilst mucosalis isolates previously had proved remarkably homologous, a serologically distinct variant has been recovered from some cases of PIA and HE. A study of the incidence of PIA in a small closed minimal disease herd was undertaken; and also an investigation was carried out on "3 weeks scours" on a farm on which PIA was an endemic problem.

Infectivity experiments were carried out in neonatal and post-weaned piglets using cultures of mucosalis. The neonatal piglet was found to be more susceptible to infection under the conditions of the experiments. Pharmacologically-mediated inhibition of peristalsis increased the susceptibility of the post-weaned pigs to mucosalis infection. Although infections were established in both the intestinal mucosa and the oral cavity in neonatal pigs for up to six weeks, only small numbers of mueosalis were recovered and lesions of PIA were not seen.

Transmission experiments, using homogenised mucosa from animals affected with PIA, were also undertaken. PIA and NE were successfully reproduced in neonatal pigs but not in post-weaned animals.

The recovery phase of PIA was studied in both field and experimental cases. Associated with elimination of mucosalis. there was resolution of the adenomatous lesions and return of the intestinal mucosal architecture to normal. A study of cases of proliferative haemorrhagic enteropathy (PHE) showed many similarities to the recovery phase of PIA but there were also important features which possibly explain the different clinical picture seen with PHE.