Invasive meningococcal disease strikes fast—and often without warning—especially in close-contact environments like college dorms and military barracks. While it’s rare, the consequences can be devastating: death within hours, or lifelong complications like limb loss and brain damage. In this episode Heather explains all about how Neisseria meningitidis, a bacterium that many carry unknowingly, transforms from harmless passenger to lethal invader. With rising case numbers and low vaccine uptake, especially for serogroup B, understanding the risks and protections has never been more urgent.