Experimental Neonatal Diarrhoea Caused By An Enteropathogenic Strain Of Escherichia Coli In Piglets: A Study Of The Disease And The Effect Of Vaccinating The Dam

Abstract

Summary Experimental neonatal diarrhoea (E.N.D.) was produced in litters of piglets derived from gilts after oral administration at birth of a washed live suspension of an enteropathogenic strain of Escherichia coli belonging to the O149:K91(B), K88ac(L) group. Different litters varied in their susceptibility to the strain; the mortality attributable to E.N.D. was 38 per cent. (20 of 53 piglets) but two of six litters were almost completely resistant to the enteropathogenic strain. This resistance did not appear to be related to a high level of bacterial agglutinins, somatic (O) antibodies or bactericidal activity in the colostrum. A formalin-killed vaccine derived from two isolates of the O149:K91(B), K88ac(L) group was administered in two doses without an adjuvant to six gilts during the last 4wk of pregnancy. The mortality attributable to E.N.D. in piglets from vaccinated dams was 20 per cent (11 of 54 piglets) following administration of the challenge dose. Although there was a reduction in the mortality of piglets from vaccinated compared with non-vaccinated dams, the reduction was not significant when the variation between Utters was taken into account. However, the bacteriological observations suggest that an antibacterial factor impaired the ability of the enteropathogenic strain to become established in the intestinal tract of piglets from vaccinated dams. This factor did not appear to be related to a high level of bacterial agglutinins, somatic (O) antibodies or bactericidal activity in colostrum and has yet to be identified in vitro.