RESUMO
A trial to control abortion and nervous symptoms in sheep was carried out through an experiment applied on 2 groups of pregnant ewes. First group included 6 ewes immunized S/C with 2ml suspension of local isolated field living L. monocytogenes [diluted 8X10 [9]/ml] and challenged with 2 ml of the same strain of L. monocytogenes [2xl0 [2]/ml]. This group revealed gradual increase in the antibody titre till delivery using serum agglutination test [SAT] and FLISA. In addition, failure to reisolate L. monocytogenes in the rectal and vaginal swabs and no significant lesions characteristic for L. monocytogenes infection were detected pathologically. The second group [control group] consisted of 3 pregnant ewes, two of which challenged as the first group and the third ewe still alive and delivered normally and its lambs challenged as control group. The antibody titre of the 2 challenged pregnant ewes of this group [one died with nervous symptoms and the other aborted] was not present till challenge and increase somewhat after challenge. Moreover, L. monocytogenes was re isolated from rectal and vaginal swabs and from collected organs of dead ewe and from placenta of aborted one and from foeti. Histopathologically, the dead ewe revealed focal gliaosis, necrosed neurons, neurophagia, endothelial cell hyperplasia and perivascular infiltration by few number of lymphocytes and glia cells in the brain. Necrotic hepatocytes in the liver, follicular depletion in the spleen, exocytosis and focal areas of necrobiotic changes in the uterine epithelium and necrosis in the tips of the villi of the placenta. The foeti of dead and aborted ewes showed foci of coagulative necrosis, hemolysed R.B.C.s and hemosidrosis in the liver. In this experimental work, a recommendation of using live preparation of L. monocytogenes vaccine has afforded a hope in control of listeriosis in pregnant ewes. There is a significant increase in antibody response in the serum of immunized dams and their lambs suggested the role of dam vaccination in protection of neonate against listeriosis