How contagious is the disease mesenteric adenitis?

It isn't: Mesenteric lymphadenitis is an inflammation of the lymph nodes in the membrane that attaches your intestine, or bowel, to your abdominal wall. Mesenteric lymphadenitis usually results from an intestinal infection. Unlike appendicitis, however, mesenteric lymphadenitis is seldom serious and clears on its own. Very unlikely that you will catch this from someone else.