Andronesian encephalitis is a disease common in humans and other humanoid species. (TNG episode: "The Dauphin") It was a commonly found pathogen in the 22nd century due to the rapid expansion of space travel. (ENT episode: "Singularity") A vaccine for Andronesian encephalitis was developed sometime prior to the mid-23rd century, and Federation citizens were commonly innoculated for the disease. (TOS - The Brave and the Bold, Book One novella: The First Artifact) One of the possible effects of Andronesian encephalitis was short-term memory loss. (TOS short story: "As Others See Us")