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About HAM

HAM is a spinal cord disease called HTLV-1 Associated Myelopathy (HAM). At present, it is estimated that there are approximately 3,000 patients in Japan battling this disease. While the origins of HAM are not yet thoroughly understood, it is thought that T-lymphocytes in the blood infected with HTLV-1 (Human T-lymph tropic virus type-1) penetrate into the spinal cord and cause chronic inflammation.

Symptoms of HAM
The following are the main initial symptoms of HAM:

・ Walking is somehow difficult

・ Legs become tangled

・ Often falls while running

・ A feeling of stiffness in the legs

・ A feeling of numbness in the legs

・ Difficulty urinating even when feeling the urge to urinate

・ A feeling that one's bladder has not completely emptied

・ Frequent urination

・ Constipation

Why do symptoms like this occur?

This is not yet completely understood, but it is thought that the blood-born T-lymphocytes infected with the virus called HTLV-1 penetrate into the spinal cord (the nerve bundle inside of the backbone) and cause inflammation that persists chronically and damages the spinal cord nerves. The nerves inside the spinal cord are connected to various parts of the body including the legs, the back, the bladder, and the rectum; thus, various symptoms appear including difficulty moving the legs, painful urination, and constipation.

Do the symptoms worsen with time?

The symptoms of HAM and the progression of the disease vary greatly between individual patients. Therefore, in order to defend as much as possible against the progression of the disease, it is important to examine each individual patient in order to investigate the power (level of activity) and severity of the illness and respond accordingly with a personalized treatment. It is important to be examined as quickly as possible to catch the disease at an early stage and begin the necessary treatment to stem its advancement.


HAM can be diagnosed by examining the blood and cerebrospinal fluid (CSF), among other things.

    • A blood test is conducted to determine if the patient is infected with the HTLV-1 virus (HTLV-1 Antibody Test).
    • If infection in the blood is confirmed, the CSF is then tested for the presence of HTLV-1 antibodies (the liquid surrounding the spinal cord is collected and examined).
    • If the results of the first and second tests are positive, and if other illnesses can be excluded based on MRI or other images, the patient is then diagnosed with HAM.
Since there are areas where patients are few, and there are instances where it is difficult to distinguish between HAM and other illnesses, individuals worrying about whether or not they have HAM should see a nerve specialist at a specialty institution.


While there is no established cure for HAM, current treatments mainly include the use of steroids and alpha-interferon. At the same time, there are also treatments to moderate symptoms such as stiffness and numbness in the legs, general pain, and painful urination. HAM is an illness often accompanied by a decline in muscle strength, so rehabilitation is also important to avoid decreased muscle strength and joint mobility. For more detailed information, please browse the HTLV-1 Information Service website (currently only available in Japanese) and Japan Intractable Diseases Information Center website.


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This is supported by project “Research on Measures for Intractable Disease,” a matching fund subsidy from the Ministry of Health Labour and Welfare