A Simple Guide to HTLV Infection: What you need to know


  • What is HTLV?
  • What Does HTLV 1 Do?
  • How Do People Get HTLV?
  • HTLV Symptoms
  • Medical Conditions Caused by HTLV
  • HTLV Testing
  • HTLV Treatment
  • Living with HTLV
  • Conclusion

  • What is HTLV?

    HTLV stands for Human T-cell Lymphotropic Virus. There are different types, like HTLV-1, HTLV-2, and even HTLV-3 and 4. But HTLV-1 is the most likely to be associated with human disease. Around 5 to 10 million people have it. It's mostly found in places like:

    • Caribbean
    • South America
    • Romania
    • Iran
    • much of Africa
    • Japan
    • Melanesia
    • indigenous population of Australia

    In the UK, around 22,000 are living with the HTLV-1 virus.

    HTLV-2 is mostly found in indigenous Americans and those from Western Africa, and it's rarer in the UK than HTLV-1. It spreads the same way as HTLV-1, especially among people who inject drugs. Still, recent data on its prevalence in the UK's drug-using population is lacking. HTLV-2 usually leads to milder diseases compared to HTLV-1, but there's not much information on how it affects health. Therefore, what follows is mostly about HTLV-1.

    What Does HTLV-1 Do?

    HTLV-1 attacks certain cells in our blood. This can change how our body fights off illnesses. It might lead to serious health problems. These include a type of cancer called adult T-cell leukemia/lymphoma. Another issue is a nerve condition known as HAM/TSP. HTLV-1 can also cause other health issues, like eye problems, muscle issues, joint pain, and more. Most people with HTLV-1 don't feel sick, though. Only a few will get these health problems.

    How Do People Get HTLV?

    HTLV is transmitted in several ways:

    • Through blood, by receiving transfusions or sharing needles.
    • From mother to child in pregnancy and through breastfeeding.
    • Via sexual contact with an infected person.


    HTLV Transmission Rate and Awareness

    Not everyone with HTLV passes it on. But knowing about HTLV, how it spreads, and where it's common helps us stay aware and safe.

    The WHO estimates mother to child transmission rates ranging from 3.9% to 27%.

    Several studies have reported transmission rates of up to 63% from blood transfusions from a donor with HTLV-1. One study reported transmission rate of 87% from tissue transplants from positive donors. 


    HTLV Symptoms

    Many people with HTLV may not show symptoms for a long time. However, when symptoms appear, they can vary widely. Here’s what to look out for:

    • Fatigue and general weakness.
    • Skin rashes and irritation.
    • Swelling of the lymph nodes.
    • Muscle and joint pain.

    HTLV Seroconversion Symptoms

    Seroconversion is when your body starts making antibodies against HTLV after being infected. During this phase, some people might experience flu-like symptoms. These can include fever, fatigue, and swollen lymph nodes. However, these signs can be easily overlooked or mistaken for other illnesses.


    Medical Conditions Caused by HTLV

    The Human T-cell Lymphotropic Virus (HTLV) is more than just a virus; it's a potential trigger for serious medical conditions. Among these, HTLV 1 is notorious for its association with specific diseases, including tropical spastic paraparesis and HTLV 1 lymphoma. Understanding these conditions can help in early detection and management.

    Tropical Spastic Paraparesis (TSP)

    TSP is a neurological condition linked to HTLV infection. It affects the spinal cord, leading to muscle weakness and stiffness, primarily in the legs. This can cause difficulty walking or even paralysis in severe cases. Symptoms of tropical spastic paraparesis include:

    • Muscle stiffness and spasms.
    • Lower back pain.
    • Weakness in the legs.
    • Urinary incontinence.

    Can You Die from HTLV?

    While HTLV itself is not directly fatal, the conditions it can lead to, such as HTLV-1 lymphoma and other forms of cancer, can be life-threatening. Early detection and treatment are crucial for improving outcomes.

    HTLV-1 Lymphoma

    HTLV-1 lymphoma is a type of cancer that affects the lymphatic system. It's a rare but aggressive form of non-Hodgkin lymphoma directly linked to the HTLV-1 virus. Symptoms can include:

    • Swollen lymph nodes.
    • Fatigue.
    • Fever and night sweats.
    • Unexplained weight loss.

    HTLV 1 Cancer

    Apart from lymphoma, HTLV-1 can also be associated with other types of cancer, including adult T-cell leukemia/lymphoma (ATLL). This cancer affects the blood's T-cells, which are crucial for the immune system's function.

    HTLV 1 Associated Myelopathy Symptoms

    HTLV-1 associated myelopathy, also known as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), shares symptoms with TSP but is specifically linked to HTLV-1 infection. It results in chronic inflammation of the spinal cord. Symptoms include:

    • Progressive weakness and stiffness of the legs.
    • Lower back pain.
    • Bladder and bowel dysfunction.
    • Mild sensory disturbance in the lower extremities.


    HTLV Testing

    To diagnose an HTLV infection, doctors test for HTLV antibodies (IgG) in blood using an enzyme-linked immunoassay test. A positive test means that HTLV might be present, and needs to be confirmed with another more specialised test such as Western blot or line assay that also tells which type of HTLV it is. If results aren't clear, a PCR test is done on whole blood to find the virus's DNA.

    False positives in the HTLV antibody test can occur in initial tests due to laboratory error or the presence of other antibodies that react with HTLV test components. Specialised testing then confirms whether or not this is a true positive test to ensure 100% accuracy.

     HTLV Home Test Kit

    HTLV Laboratory Test (London)

    HTLV Testing in Pregnancy and Fertility

    HTLV testing is crucial for pregnant women and individuals undergoing fertility treatments, such as IVF. An anti-HTLV test or HTLV antibodies can inform fertility decisions and prevent transmission of the virus from mother to baby.

    HTLV Diagnosis and the Window Period

    Finding out if someone has HTLV involves blood tests. The window period is the time between catching the virus and when tests can spot it. This period is crucial for accurate testing but is not certain exactly how long this is.  However, as an example in practice, the blood transfusion and organ transplant service in the UK gives an antibody window period of 3 months. They say that the risk of missing an infection after 3 months following exposure is low.

    HTLV and Blood Donation

    If you've had a false positive for HTLV when donating blood, there's a waiting period before trying again. This helps keep the blood supply safe.


    HTLV Treatment

    Currently, there is no definitive cure for HTLV. However, treatments are available to manage symptoms and complications arising from HTLV-related conditions. The approach to treatment varies depending on the specific illness caused by the virus.

    HTLV-1 Treatment

    For individuals diagnosed with HTLV-1, the treatment focuses on managing symptoms and preventing the progression of associated diseases. Here are some treatment avenues:

    • Antiviral therapy: While not a cure, antiviral medications can help manage viral load and reduce the risk of HTLV 1-related conditions.
    • Immunomodulatory therapy: This treatment can help manage symptoms of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and other inflammatory conditions caused by the virus.
    • Cancer treatment: For HTLV-1-related lymphoma or leukaemia, treatment may include chemotherapy, radiation therapy, and in some cases, stem cell transplantation.

    Is There a Cure for HTLV?

    As of now, there is no cure for HTLV. Research is ongoing, and scientists are working to find more effective treatments and potentially a cure in the future. The focus remains on managing symptoms and improving the quality of life for those affected.

    Supportive Care

    In addition to specific treatments for HTLV-1-associated conditions, supportive care plays a critical role. This can include:

    • Physical therapy: Especially important for those with HAM/TSP, to improve mobility and manage spasticity.
    • Pain management: Utilizing medications and therapies to reduce discomfort caused by HTLV 1-related conditions.
    • Psychological support: Counselling and support groups can help patients and their families cope with the diagnosis and its impact on daily life.

    Living with HTLV

    Many with HTLV-1 don't get sick. But some can have nerve problems, trouble with bladder control, and other health issues. These might not always be severe but can affect daily life. A high level of the virus in the blood can make these problems more likely.


    While there is currently no cure for HTLV, various treatment options can help manage the symptoms and complications of diseases associated with the virus. However, prevention is better than cure. Testing is vital to find out if you have HTLV to avoid transmission especially if your planning for a baby.  It's essential for patients and their healthcare providers to work closely together to develop a comprehensive care plan that addresses the individual's needs. Continued research and advancements in treatment offer hope for more effective therapies in the future.


     HTLV Home Test Kit

    HTLV Laboratory Test (London)