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HTLV-1 associated myelopathy

The term “tropical spastic paraparesis” (TSP) has been used for several decades to describe a chronic and progressive disease of the nervous system that affects adults living in equatorial areas of the world. TSP is now called HTLV-1-associated myelopathy (HAM)/tropical spastic paraparesis (TSP). HAM/TSP can cause:

  • Progressive weakness
  • Stiff muscles
  • Muscle spasms
  • Sensory disturbance
  • Sphincter dysfunction

The cause of HAM/TSP was obscure until the mid-1980s, when a connection was established between the human retrovirus—called “human T-cell lymphotrophic virus type 1” (also known as HTLV-1)—and HAM/TSP. The HTLV-1 retrovirus is thought to cause at least 80 percent of the cases of HAM/TSP by weakening the immune system.

Most people with HAM/TSP have few or no symptoms throughout their lives. In addition to neurological symptoms of weakness and muscle stiffness or spasms, in rare cases individuals with HAM/TSP also may have:

  • Uveitis (inflammation of the uveal tract of the eye)
  • Arthritis (inflammation of one or more joints)
  • Pulmonary lymphocytic alveolitis (inflammation of the lung)
  • Polymyositis (an inflammatory muscle disease)
  • Infectious dermatitis (inflammation of the skin)
  • Keratoconjunctivitis sicca (persistent dryness of the cornea, which is the clear, front “window” of the eye, and conjunctiva, which is the mucous membrane that covers the front of the eye and lines the inside of the eyelids)

    The other serious complication of HTLV-1 infection is the development of adult T-cell leukemia or lymphoma. Nervous system and blood-related complications happen only in a very small percentage of people with HAM/TSP.

    HAM/TSP is a progressive disease (in other words, it gets worse as time passes), but it is rarely fatal. Most people with HAM/TSP live for several decades after the diagnosis. The outlook improves if they take steps to prevent urinary tract infections and skin sores, and if they participate in physical and occupational therapy programs.

    The HTLV-1 virus is transmitted from person to person through infected cells. Transmission can happen through:

    • Breast-feeding by mothers who have high levels of antibodies to HTLV-1 in their blood (this is called being “seropositive to HTLV-1”)
    • Sharing infected needles during intravenous drug use
    • Having sexual relations with a seropositive partner

    There is no established treatment program for HAM/TSP. Corticosteroids may relieve some symptoms, but they usually don't change the course of the disorder. Interferon alpha (a pharmaceutical drug) may help for short periods. Interferon beta (a pharmaceutical drug) may improve some aspects of HAM/TSP. Stiff and spastic muscles can be treated with baclofen (Lioresal®) or tizanidine. Urinary dysfunction may be treated with oxybutynin.

    How can I or my loved one help improve care for people with HTLV-1-associated myelopathy/tropical spastic paraparesis?

    Consider participating in a clinical trial so clinicians and scientists can learn more about HAM/TSP and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

    All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

    For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with HAM/TSP at

    Where can I find more information about HTLV-1-associated myelopathy/tropical spastic paraparesis?

    Information may be available from following resources:

    National Cancer Institute (NCI)
    Phone: 800-422-6237 or 800-332-8615

    National Institute of Allergy and Infectious Diseases (NIAID)
    Phone: 301-496-5717

    Content source: Accessed June 23, 2023.

    The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, MedLink, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.

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