Jonas Salk. The polio vaccine passed field tests and was first administered to the general public in 1955.

Butterfly. The thyroid is the largest endocrine gland in the body.

50 Million. Epilepsy is a chronic disorder of the brain which is characterized by recurrent seizures as a result of excessive electrical discharge in brain cells.

20%. According to the World Health Organization, about half of mental disorders begin before the age of 14.

Cerebral Trauma. The cerebrum is the largest part of the human brain.

Vitamin D. A bone softening disease is rickets.