According to her autobiography, The Story of My Life, Helen Keller was born with the ability to hear and to see. But when she was 19 months old, she fell suddenly ill with a condition that "closed" her eyes and ears and gave her the same sense of "unconsciousness" as a newborn baby.
At the time, the doctor diagnosed Helen with "acute congestion of the stomach and the brain." The word "congestion" is a medical term that means that Helen had an abnormal amount of blood in these organs. What caused this congestion, however, was not explained by Helen's doctors and remains a mystery even now.
Modern doctors have suggested that Helen's sudden loss of sight and hearing may have been caused by meningitis or a common childhood disease, like scarlet fever. Whatever the case, this disease left Helen as quickly as it came. Her sight and hearing, however, never returned.
Helen Keller was a little more than two years old (19 months) when she lost her sight and ability to hear. While there was no official diagnosis of the disease except "brain fever," the symptoms lead to the modern belief that she had meningitis or scarlet fever. The description of the disease was "an acute congestion of the stomach and the brain." According to both Helen Keller's autobiography and the accounts of various historians, she came close to death with a high fever over the course of several days. A third disease, encephalitis, is also a possibility; however, it is extremely rare. The fourth possibility was rubella. When Helen Keller was two Alabama was experiencing an epidemic.
Helen Keller's account of the disease speaks of the loss of her sight as a gradual process wherein her eyes felt dry and hot. Tests done later in her life proved that she was not able to see any light or objects. Likewise the same tests found that there was no vibration or "air conduction" in either ear. Whichever disease Helen Keller experienced, it robbed her of her vision and hearing completely. Because she was so young, the inability to hear rendered her mute without a conduit to learn speech.