7.3 How long does protection last and is the vaccine effective worldwide?

Field and experimental observations indicate that the period of immunity following correct Enterisol^® Ileitis vaccination persists until the end of fattening. As with all vaccines, it is important to vaccinate pigs BEFORE significant exposure to the actual pathogen.

This is the first vaccine developed against L.intracellularis, and contrasts with the lack of vaccines available for other enteric diseases of pigs. Despite swine dysentery being a major enteric disease of pigs, and its causative agent, Brachyspira hyodysenteriae being cultured in vitro since 1970, no reliable vaccine has ever been marketed against it. Post-weaning enterotoxigenic Escherichia coli infections remain common and important, yet fimbrial bacterins or other vaccine approaches have proved of limited benefit. The success of the Lawsonia vaccine may be partly due to an increased exposure of this agent to the immune system of the pig. Inges­tion of L.intracellularis by intestinal mucosal macrophages, specific humoral and mucosal responses and antigen-related mitogenesis of pig blood lymphocytes all occur following oral infection. In contrast, B.hyodysenteriae and E.coli usually remain within the intestinal lumen following oral infection.

The isolate of Lawsonia intrcellularis on which Enterisol^® Ileitis is based was obtained from a pig in Denmark. The efficacy of the vaccine has been demonstrated in field studies in USA, Germany, France, Denmark, Japan and Australia. Furthermore, genome and protin analysis of Lawsonia intracellularis from a wide range of geographical locations have shown that it is a monotype bacterium. Accordingly the vaccine will provide a worldwide protection.

Recent research results have shown that oral administration of Enterisol^® Ileitis by direct drench or via drinking water to young pigs provides substantial amounts of protection against subsequent challenge exposure with virulent L.intracellularis isolates of similar and different origin (Kroll et al. 2004).