Lawsonia intracellularis is a bacterial pathogen which causes disease in a wide range of animals, mainly pigs. The disease has two clinical manifestations in pigs: (1) an acute hemorrhagic form often called porcine hemorrhagic enteropathy, and (2) a more chronic proliferative form often referred as porcine intestinal adenomatosis. Lawsonia intracellularis though primarily recognized in pigs, is spreading to a wide range of mammals. Based on 16SrRNA gene sequence, Lawsonia intracellularis is related to Desulfovibio, a sulfate-reducing bacteria and Bilophila wadsworthia (MicrobeWiki: Lawsonia intracellularis).
4. Microbial Pathogenesis
The bacterial pathogen invades the intestinal epithelial cells which causes hyperplasia of the infected cells and leads to the process of disease pathogenesis. Lawsonia intracelluaris is an intracellular enterophathogen that is the cause of intestinal hyperplasia which is an abnormal increase in the number of cells in an organ or a tissue with consequent enlargement (MicrobeWiki: Lawsonia intracellularis).
5. Host Ranges and Animal Models
Though the major animal that is most susceptible are pigs, Lawsonia intracellularis has been detected laboratory animals such as primates, pigs, horses, dogs, rats, guinea pigs, rabbits and hamsters. Though there is evidence of infection in primates, there is currently no direct evidence that Lawsonia intracellularis can infect humans (MicrobeWiki: Lawsonia intracellularis).
6. Host Protective Immunity
The humoral response of pigs against L. intracellularis infection is believed to be weak and short-lived (Guedes and Gebhart, 2003).
1. Guedes and Gebhart, 2003: Guedes RM, Gebhart CJ. Onset and duration of fecal shedding, cell-mediated and humoral immune responses in pigs after challenge with a pathogenic isolate or attenuated vaccine strain of Lawsonia intracellularis. Veterinary microbiology. 2003; 91(2-3); 135-145. [PubMed: 12458163].
2. Kroll et al., 2004: Kroll JJ, Roof MB, McOrist S. Evaluation of protective immunity in pigs following oral administration of an avirulent live vaccine of Lawsonia intracellularis. American journal of veterinary research. 2004; 65(5); 559-565. [PubMed: 15141873].
