(dentistry) periodontitis

(pathology) collagenosis, collagen disease

(fiction) Hanahaki, an illness affecting those consumed by unrequited love that manifests as the coughing up of flowers, which clears up upon reciprocation. A fictional illness, it has found popularity among both Japanese and foreign online fanfic (especially) artists and authors for its poetic quality.

anthropozoonosis

a healthy diet and medicine are equally important for health, an apple a day keeps the doctor away

(medicine) zoonosis, more specifically, amphixenosis: a disease that can infect both humans and animals

COVID-19

(idiomatic) Speak no ill-fated words; let no feeding cause you ailment; literally Diseases enter through the mouth, disasters come out of the mouth.

(medicine) severe invasive streptococcal disease