Human T cell Lymphotropic Viral Infection


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Human T cell lymphotropic virus (HTLV) infects a type of white blood cell called a T-cell or T-lymphocyte. White blood cells are a type of cell that helps fight infection. HTLV is a type of retrovirus that can cause cancer. It is different than the retrovirus that causes AIDS.


HTLV infection is caused by a specific virus.

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Risk Factors

There are 2 types of HTLV: HTLV-I and HTLV-II.

Factors that may increase the chances of getting HTLV-I:

  • Living in an area where the virus is common such as Southern Japan, Caribbean countries, parts of Africa and South America, the Middle East, and Melanesia
  • Being breastfed by an infected mother
  • Receiving a blood transfusion or transplant in the US before 1988
  • Having unprotected sex with someone who is infected with the virus, who is an injection drug user, or who is from an area where the virus is common
  • Injection drug use

People of American Indian or African Pygmy descent are at greater risk for HTLV-II.

Factors may that increase the chances of getting HTLV-II:

  • Being breastfed by an infected mother
  • Receiving a blood transfusion in the US before 1988
  • Having unprotected sex with someone who is infected with the virus or who is an injection drug user
  • Injection drug use


More than 95% of people with HTLV do not have symptoms. However, having the virus puts you at higher risk of developing certain conditions.

  • If you are infected with the HTLV-I virus, it is possible that you may develop
    • Adult T-cell leukemia (ATL). This disease involves cancer of a specific group of white blood cells.
    • Opportunistic infections, including Strongyloides stercoralis hyperinfection
    • Inflammation of the eyes, joints, muscles, lungs, or skin (rare)

If you are infected with HTLV-I or HTLV-II, you may also develop a disorder of the nervous system known as HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It can cause weakness, numbness and stiffness in the legs, and difficulty walking.


You will be asked about your symptoms and medical history. A physical exam will be done.

HTLV infection can only be diagnosed with a specific blood test. The presence of HTLV antibodies is a sign of infection with the virus.


There is no treatment that can remove the virus from the body. Treatment is aimed at managing HTLV-associated diseases and reducing their symptoms.

To prevent spreading HTLV to others:

  • Do not donate plasma, bone marrow, organs, semen, or breast milk.
  • Do not breastfeed your baby.
  • Avoid unprotected sex.
  • Avoid sharing needles or syringes.


To help reduce the chances of HTLV infection:

  • Avoid unprotected sex. If your partner has the virus, discuss ways to prevent the spread of the virus with your doctor.
  • Avoid sharing needles or syringes.


Centers for Disease Control and Prevention
National Institute of Allergy and Infectious Diseases


The Canadian Hematology Society


Human T-cell lymphotropic virus type 1 (HTLV-1). EBSCO DynaMed Plus website. Available at: http://www.dynamed... . Updated February 19, 2018. Accessed March 13, 2018.
Human T-lymphotropic virus (HTLV). New York State Office of Alcoholism and Substance Abuse Services website. Available at: Accessed March 13, 2018.
What is HTLV-II? The National Centre for Human Retrovirology website. Available at:
...(Click grey area to select URL)
Accessed March 13, 2018.
Last reviewed March 2018 by EBSCO Medical Review Board Marcie L. Sidman, MD
Last Updated: 3/13/2018

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