US civil rights campaigner Jesse Jackson his suffering from Parkinson's disease.
In a letter to supporters the 76-year-old said family and friends noticed a change in him about three years ago.
He said he could no longer ignore symptoms of the chronic neurological disorder that causes movement difficulties and had been receiving outpatient care for two years
"Recognition of the effects of this disease on me has been painful, and I have been slow to grasp the gravity of it," he wrote.
