Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is recognized as an important immuno-regulatory receptor in the host response to infections with bacteria that are colonizing human mucosal surfaces such as Helicobacter pylori, Neisseria meningitidis, Neisseria gonorrhoeae, Moraxella catarrhalis, and Fusobacterium spp. The gene discussed is CEACAM1; the disease is infection.