Pathogenesis of Lawsonia involves which sequence of events in enterocytes?

Pathogenesis of Lawsonia involves which sequence of events in enterocytes?

• A. Lysis of enterocytes by toxins leading to villus atrophy
• B. Attachment to enterocytes, internalization, and upregulation of cell division in crypt cells
• C. Spread systemically via blood to distant organs
• D. Destruction of goblet cells by bacteria

Answer: (B)

Lawsonia intracellularis causes disease by living inside enterocytes and driving the cells to proliferate. The bacteria first attach to the enterocyte surface, then are internalized and replicate within the cells. This intracellular presence stimulates crypt epithelial cells to divide more than normal, leading to crypt hyperplasia and a thickened, inflamed mucosa with villus blunting. This sequence—attachment to enterocytes, internalization, and crypt cell proliferation—best explains the pathogenesis. It’s not due to toxin-caused lysis of enterocytes, nor a systemic spread, and goblet cell destruction is not the primary mechanism.

Lawsonia intracellularis causes disease by living inside enterocytes and driving the cells to proliferate. The bacteria first attach to the enterocyte surface, then are internalized and replicate within the cells. This intracellular presence stimulates crypt epithelial cells to divide more than normal, leading to crypt hyperplasia and a thickened, inflamed mucosa with villus blunting. This sequence—attachment to enterocytes, internalization, and crypt cell proliferation—best explains the pathogenesis. It’s not due to toxin-caused lysis of enterocytes, nor a systemic spread, and goblet cell destruction is not the primary mechanism.