Tropical spastic paraparesis (TSP) is a slowly progressive spastic paraparesis caused by the human T-cell lymphotropic virus-1 (HTLV-1), with an insidious onset in adulthood.

The disease may remain undetected for years after infection is contracted.

While the disease is incurable, significant improvement has been reported in the condition of TSP patients treated with corticosteroids

isolated cases have been diagnosed in the southeastern United States and other places in the United States

TSP is most frequently found in: the Caribbean, Japan, the Seychelles Islands, regions of South America, western Africa