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Disease Profile

HTLV-1 associated myelopathy/tropical spastic paraparesis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

HAM/TSP; Human T-cell leukemia virus type 1 associated myelopathy/tropical spastic paraparesis; Tropical spastic paraparesis (formerly)


Nervous System Diseases


HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a progressive disease of the nervous system that affects less than 2% of people with HTLV-1 infection. Signs and symptoms vary but may include slowly progressive weakness and spasticity of one or both legs, exaggerated reflexes, muscle contractions in the ankle, and lower back pain. Other features may include urinary incontinence and minor sensory changes, especially burning or prickling sensations and loss of vibration sense.[1] The reason some people with HTLV-1 infection develop HAM/TSTP is not well understood.[1] Treatment generally aims to control the specific symptoms, as there is no standard treatment available.[2] Interferon alpha may be beneficial over short periods, and some aspects of the disease may be improved with interferon beta.[3] Other medications may include immune globulin, oral corticosteroids, and muscle relaxers such as baclofen or tizanidine.[2][4]


Signs and symptoms of HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) vary but may include:[1][3][4]

  • Slowly progressive weakness and spasticity of one or both legs
  • Exaggerated reflexes (hyperreflexia)
  • Stiff muscles
  • Muscle contractions in the ankle (ankle clonus)
  • Lower back pain
  • A 'weak' bladder and/or urinary incontinence
  • Minor sensory changes, especially burning or prickling sensations and loss of vibration sense


Treatment generally aims to control the specific symptoms, as there is no standard treatment available.[2] Interferon alpha may be beneficial over short periods, and some aspects of the disease may be improved with interferon beta.[3] Stiff and spastic muscles may be treated with lioresal or tizanidine, and urinary dysfunction may be treated with oxybutynin.[3] Corticosteroids were reported to slow progression in one case series and reduce neurologic disability in another. However, others have reported no such benefit with corticosteroids and there have been no randomized clinical trials.[1]

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Merck Manual for health care professionals provides information on HTLV-1 associated myelopathy/tropical spastic paraparesis.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss HTLV-1 associated myelopathy/tropical spastic paraparesis. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles


  1. Scadden DT, Freedman AR, Robertson P. Human T-lymphotropic virus type I: Disease associations, diagnosis, and treatment. UpToDate. Waltham, MA: UpToDate; February 16, 2016; https://www.uptodate.com/contents/human-t-lymphotropic-virus-type-i-disease-associations-diagnosis-and-treatment.
  2. Sandbrink F. Tropical Myeloneuropathies Treatment & Management. Medscape Reference. January, 2015; https://emedicine.medscape.com/article/1166055-treatment.
  3. Tropical Spastic Paraparesis Information Page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Tropical-Spastic-Paraparesis-Information-Page. Accessed 7/12/2017.
  4. Rubin M. Tropical Spastic Paraparesis/HTLV-1–Associated Myelopathy (TSP/HAM). Merck Manual. October, 2016; https://www.merckmanuals.com/professional/neurologic-disorders/spinal-cord-disorders/tropical-spastic-paraparesis-htlv-1%E2%80%93associated-myelopathy-tsp-ham.

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