Xenomaladies are diseases, mental illnesses that are not possible (for now) to acquire in the real world. These are fictive diseases(/mental illnesses) where people can identify with.
(Xenomaldies who are mental are called “xenopsyri”)
Example: hanahaki disease “ is a fictional disease in which the victim coughs up flower petals when they suffer from one-sided love. It ends when the beloved returns their feelings (romantic love only; strong friendship is not enough), or when the victim dies. It can be cured through surgical removal, but when the infection is removed, the victim’s romantic feelings for their love also disappear.”