Ogden Nash - The Germ

A mighty creature is the germ,
Though smaller than the pachyderm.
His customary dwelling place
Is deep within the human race.
His childish pride he often pleases
By giving people strange diseases.
Do you, my poppet, feel infirm?
You probably contain a germ.

Ogden Nash

http://www.poemhunter.com/poem/the-germ/