Pathogenesis of Mycobacterium avium subspecies paratuberculosis infectionsin ruminants: still more questions than answers

Mycobacterium avium subspecies paratuberculosis is the etiologic agent of p aratuberculosis (Johnes disease), a chronic enteritis in ruminants, which i s one of the most widespread bacterial diseases of domestic animals, causin g enormous economic losses worldwide. Though the disease was first describe d more than a century ago, the biology of the infecting organism and the me chanisms of its interactions with the host still remain a mystery. In this review, recent advances made on pathogenesis of paratuberculosis are summar ized and future challenges are discussed. (C) 1999 Editions scientifiques e t medicales Elsevier SAS.