infectious
in-fec-tious
adjective
Able to spread disease from one person or organism to another.
"Measles is a highly infectious childhood disease."
adjective
Spreading quickly to others, especially an emotion, feeling, or quality.
"Her infectious laugh made everyone smile."
Thesaurus
Synonyms: corrupting, contagious, catching, transmissible, contaminating, transmittable, contractable, communicable, infective, septic, infected
Antonyms: noninfectious