Human T-cell Lymphotropic Virus (HTLV) Testing
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- Also Known As:
- HTLV-I/II Antibodies
- HTLV-I/II by PCR
- Formal Name:
- Human T-Lymphotropic Virus Types I/II Antibodies

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At a Glance
Why Get Tested?
To detect a human T-lymphotropic virus (HTLV) infection; to help diagnose the cause of adult T-cell leukemia or lymphoma or HTLV-associated myelopathy
When To Get Tested?
When you have signs or symptoms that suggest that you may have an HTLV-associated neoplastic condition or demyelinating disorder, especially when you have identified risk factors; rarely when you have donated blood and been told that you are positive for HTLV antibodies
Sample Required?
A blood sample drawn from a vein in your arm; rarely a sample of cerebrospinal fluid (CSF) collected from the lower back using a procedure called a lumbar puncture (spinal tap)
Test Preparation Needed?
None
What is being tested?
Human T-lymphotropic virus (HTLV) infection is associated with certain rare diseases of T lymphocytes (T-cells), a type of white blood cell that is an important part of the body’s immune system. This test detects an HTLV infection in order to help identify the virus as the underlying cause of an individual’s leukemia, lymphoma, rare nervous system disorder, chronic pulmonary infection, uveitis, infectious dermatitis, or other inflammatory disorder.
Two types of HTLV are most commonly identified through testing: HTLV-I and HTLV-II. It is estimated that 15-20 million people worldwide are infected with HTLV. The prevalence of HTLV-1 infection is greatest in Japan, sub-Saharan Africa, the Caribbean islands, and Central and South America. HTLV-II appears to be endemic among Native American populations and is prevalent among intravenous (IV) drug users in North America and Europe.
In the United States, about 22 out of every 100,000 people are infected with HTLV, with HTLV-II infection being more common than HTLV-I infection. HTLV-II infection is associated with female sex, older age, non-white race/ethnicity, lower educational level, and residence in the Western and Southwestern U.S. Some Native American Indian populations have infection rates as high as 13%. Those most likely to be infected with HTLV-I have immigrated to the U.S. from a country where HTLV-1 infection is prevalent, are children of such immigrants, are IV drug users, or are sex workers.
An HTLV-I infection can be passed from mother to child during pregnancy or breastfeeding. Both HTLV-I and HTLV-II infections can be sexually transmitted or spread through exposure to contaminated blood as occurs with sharing of needles during IV drug use, although the majority of drug use-related infections are linked to HTLV-II. Both types may be passed through a blood transfusion or an organ transplant, but infection due to these procedures is now rare in the United States because all donors are tested for HTLV-I/II.
Other risk factors for HTLV infection include: living in parts of the world where HTLV is more common (such as those listed above); having a sexual partner who came from one of these areas; having multiple sex partners; being an IV drug user; being Native American Indian; or having a history of blood transfusions.
Both HTLV-I and HTLV-II preferentially infect T-lymphocytes. Most people infected with HTLV-I or HTLV–II will have few to no symptoms but can pass the infection on to others. After the initial infection, the virus never completely goes away but remains in the body in an inactive (latent) form. A small percentage of those infected go on to develop one of several associated diseases, typically months to many years or even decades after their initial exposure, and may then become acutely or chronically ill.
HTLV-I is associated with:
- Adult T-cell leukemia/lymphoma (ATL), a type of white blood cell cancer that may progress rapidly or slowly and cause symptoms such as fatigue, fever, and enlarged lymph nodes
- HTLV-I–associated myelopathy/tropical spastic paraparesis (HAM/TSP), a rare condition that can cause weakness in the lower limbs, muscle spasms, nerve pain, and urinary incontinence
- In some cases, other conditions such as uveitis, HTLV-I–associated infective dermatitis, rheumatoid arthritis, and Sjögren syndrome
HTLV-II is less clearly linked with specific diseases but may be associated with certain lung conditions, neurological disorders, arthritis, asthma, and dermatitis.
The body responds to an HTLV-I or HTLV-II infection by producing antibodies. These antibodies can be detected in the blood during testing. The viruses may also be directly tested using molecular tests (polymerase chain reaction, PCR) that detect the genetic material of the viruses.
Common Questions
View Sources
Sources Used in Current Review
Szczypinska EW, Wallace MR, Wainscoat B, Salas CM, Rich JD. (5 October 2015 updated.) Human T-Cell Lymphotropic Viruses. Available online at http://emedicine.medscape.com/article/219285-overview. Accessed February 5, 2017.
Goncalves, DU, Proietti FA, Ramos Ribas JC, et al. Epidemiology, Treatment, and Prevention of Human T-Cell Leukemia Virus Type 1-Associated Diseases. Clinical Microbiology Reviews. 2010;23(3):577-589.
Mayo Medical Laboratories. Human T-Cell Lymphotropic Virus Types I and II (HTLV-I/-II) Antibody Screen with Confirmation, Serum. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/9539. Accessed February 15, 2017.
National Organization for Rare Disorders. (2012 updated.) HTLV Type I and Type II. Available online at https://rarediseases.org/rare-diseases/htlv-type-i-and-type-ii/. Accessed February 5, 2017.
Sources Used in Previous Reviews
Szczypinska, E. et. al. (Updated 2012 January 11). Human T-Cell Lymphotrophic Viruses. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/219285-overview. Accessed June 2012.
(© 1995–2012). Test ID: HTLVI9539 Human T-Cell Lymphotropic Virus Types I and II (HTLV-I/-II) Antibody Screen with Confirmation, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9539. Accessed June 2012.
Slev, P. (Updated 2011 September). Human T-Lymphotropic Virus Types I, II – HTLV I, II. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/HTLV.html. Accessed June 2012.
Crane, M. (2012 March 28). FDA Approves Test for Viruses in Blood Donations. Medscape Medical News [On-line information]. Available online at http://www.medscape.com/viewarticle/761099. Accessed June 2012.
Yasunaga, J. and Matsuoka, M. (2007 May 14). Human T-Cell Leukemia Virus Type 1 Induces Adult T-Cell Leukemia: From Clinical Aspects to Molecular Mechanisms Medscape Today News from Cancer Control. v14(2):133-140. [On-line information]. Available online at http://www.medscape.com/viewarticle/556137. Accessed June 2012.
Bite, C. et. al. (2009 July 3). HIV/Human T-cell Lymphotropic Virus Coinfection Revisited: Impact on AIDS Progression. Medscape Today News from AIDS Rev. v11(1):8-16. [On-line information]. Available online at http://www.medscape.com/viewarticle/703708. Accessed June 2012.
(© 2012). General Information – HTLV. Health Protection Agency [On-line information]. Available online at http://www.hpa.org.uk/web/HPAweb&Page&HPAwebAutoListName/Page/1191942172148. Accessed June 2012.
Proietti, F. et. al. (2005). Global epidemiology of HTLV-I infection and associated diseases. Oncogene v 24, 6058–6068. [On-line information]. Available online at http://www.nature.com/onc/journal/v24/n39/full/1208968a.html. Accessed June 2012.
Rubin, M. (Revised 2007 January). Tropical Spastic Paraparesis/HTLV-1–Associated Myelopathy. Merck Manual for Healthcare Professionals [On-line information]. Available online through http://www.merckmanuals.com. Accessed June 2012.
Outhred, A. et. al. (2011 July 5). Viral Arthritides. Medscape Today News from Expert Rev Anti Infect Ther. v9(5):545-554. [On-line information]. Available online at http://www.medscape.com/viewarticle/743675. Accessed June 2012.
(Revised 2012 January 26). What are the risk factors for non-Hodgkin lymphoma? American Cancer Society [On-line information]. Available online at http://www.cancer.org/Cancer/Non-HodgkinLymphoma/DetailedGuide/non-hodgkin-lymphoma-risk-factors. Accessed June 2012.
(2010 May 27). NINDS Tropical Spastic Paraparesis Information Page. National Institute of Neurological Disorders and Stroke [On-line information]. Available online at http://www.ninds.nih.gov/disorders/tropical_spastic_paraparesis/tropical_spastic_paraparesis.htm. Accessed June 2012.
Ratliff, C. (Reviewed 2009 July). Diseases That Mimic MS. Multiple Sclerosis Foundation [On-line information]. Available online at http://www.msfocus.org/article-details.aspx?articleID=18. Accessed June 2012.
Gan, L. and Miller, F. (2012 January 1). State of the Art: What We Know About Infectious Agents and Myositis. Medscape Today News from Curr Opin Rheumatol. V 23(6):585-594. [On-line information]. Available online at http://www.medscape.com/viewarticle/751211. Accessed June 2012.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 652-653.
(June 25, 1993) Centers for Disease Control and Prevention. Recommendations for Counseling Persons Infected with Human T-Lymphotrophic Virus, Types I and II. MMWR, 42(RR-9);1-13. Available online at http://www.cdc.gov/mmwr/preview/mmwrhtml/00021234.htm. Accessed July 2012.
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