This is a regular verb. It follows the conjugation pattern of the verb hablar.
PresentPresente
Su risa contagia a toda la clase.
Her laughter spreads to the whole class.
PreteritePretérito indefinido
Mi hermano me contagió el resfriado.
My brother gave me his cold.
Present SubjunctivePresente de subjuntivo
No quiero que me contagies la gripe.
I don't want you to give me the flu.