Human T-cell lymphotropic virus (HTLV) was the first oncogenic human retrovirus to be discovered. HTLV infects the T-cells of the immune system. T-cells are a vital part of the immune system and work by attacking the cells that carry viruses or antigens. The virus is also known as the human T-cell leukaemia virus.
Experts have predominantly identified two types of the virus, HTLV (Type) 1 and HTLV (Type) 2.
Whilst HTLV does not always present symptoms, it has been reported that anywhere from 2 to 5 percent of individuals that are infected may develop HTLV related conditions or complications. HTLV 1 infection has been linked to developing adult T-cell leukaemia (ATL). HTLV 2 infection is considered to be less aggressive and infectious, but has been found to be linked to the development of hairy cell leukaemia.
Both types of the virus can also be associated with a number of chronic neurological and sensory issues.
What are the symptoms of HTLV?
Most patients with HTLV are asymptomatic (do not produce any symptoms). However, in some patients, HTLV may lead to the development of other health conditions which may produce symptoms, but there are no inherent symptoms of HTLV itself.
What complications can HTLV lead to, if untreated?
HTLV can lead to the development of conditions such as:
- Adult T-cell Leukaemia/lymphoma (ATL)
- HTLV-1 associated uveitis (HAU)
- Neuropathy (where the peripheral nerves of the limbs are affected)
- Myopathy (a general term for any disease or condition affecting muscles and motor control)
- Ulcerative colitis
- Sjögren’s syndrome
- Myelopathy or Tropical spastic paraparesis
- Infective dermatitis
- Bronchiectasis, bronchitis, and bronchiolitis
- Rheumatoid arthritis
There is little evidence that HTLV can cause cancer.
When it comes to HTLV-2, the cases are not as widespread or well documented. However there is evidence to suggest that a neuro-degenerative disease similar to the myelopathy that develops with those who have been infected with HTLV-1, may occur.
Certain bacterial infections have also been noted to affect individuals who have been co-infected with both HTLV-1 and HTLV-2.
You can read about the prognosis for ATL, HAM and TSP here.
Can you have HTLV without any symptoms?
Yes. It is possible to have HTLV and feel completely well in yourself without any symptoms.
How is HTLV transmitted?
HTLV is not commonly heard of within the UK despite being around for many years. Most individuals are not aware that they are carrying the virus as they are generally well and healthy. However, it is important to understand the risk of getting HTLV and how it can be passed on.
HTLV is passed on through direct contact of cell-containing body fluids such as semen, breast milk and blood.
You can be infected with HTLV by:
- By having unprotected sex (without a condom).
- By sharing needles.
- By having blood transfusions.
- Occupational exposure.
- It can also be passed from mother to baby via childbirth, but mainly by breastfeeding. However, HTLV is unlikely to cause severe issues for the infant.
What factors can increase the likelihood of contracting HTLV?
Your risk of contracting HTLV is increased if:
- You inject drugs, or have injected drugs in the past.
- You have sex with an individual who injects drugs.
- You were breastfed by a HTLV infected mother.
- You have unprotected sex with someone from a country known to have a high HTLV rate (and they have not been tested, or they tested positive).
- You originate from a place known to have a high HTLV rate, such as Southern Japan, South America, some parts of Africa and the Caribbean.
Can I get HTLV even if I wear a condom?
This is a difficult question to answer. Assuming that it behaves like HIV (another well-known and well-studied retrovirus), the risk of transmission from protected and unprotected oral sex is low.
It would be expected that the risk of transmission should be significantly reduced with the use of condoms during penetrative sex.
Can you tell who gave me HTLV?
In common with latent STI’s such as Herpes and HPV, it is often very difficult to work out when the infection was first acquired and from whom. This is in part due to individuals having no previous HTLV tests.
How can I prevent contracting HTLV?
Generally, practising safe sex and wearing a condom will prevent you from contracting HTLV.
More specifically you should:
- Always use a fresh needle, and safely dispose of it afterwards. Do not share needles.
- Take cautionary measures (if working in healthcare) around needles, blood and bodily fluids.
Can I take a vaccine to prevent against HTLV?
There is currently no vaccine for HTLV-1 and HTLV-2.
HTLV is diagnosed by undertaking the following blood test that look for HTLV antibodies or for the presence of the virus itself:
- HTLV-1 & HTLV-2 Antibody
- HTLV proviral DNA/RNA PCR
Learn more about Testing
Can HTLV be treated?
There is no current treatment available for those with asymptomatic HTLV-1 infection. Instead, treatment focuses on relieving symptoms of associated conditions such as ATL and HAM/TSP.
All individuals are recommended to attend regular specialist services to identify the onset of any new conditions that are associated with HTLV.
How is HTLV managed?
It may be the case that you are infected with HTLV but do not develop any secondary health conditions, and you generally remain asymptomatic. In this case, you may not even be aware that you have HTLV as it is not causing you any complications.
However, there is no need to worry if you have developed secondary health conditions as these are generally very manageable and you will be able to live a full life.
Is a test of cure possible for HTLV?
There is no test of cure possible for HTLV as it is a life-long infection and there is no treatment available. Therefore, it is impossible for HTLV to be cured.
What is the long term prognosis for someone who has HTLV?
While HTLV may not be routinely tested for in most countries, individuals who live in endemic areas and are at risk of infection are typically screened.
Evidence shows that anywhere from 2 to 5 percent of infected people will develop a form of ATL and will require chemotherapy. On average, the prognosis was reported to be anywhere between 6 months to 2 years following diagnosis and treatment.
Less than 2 percent of people infected with HTLV-1 will develop HAM/TSP. It has been reported that these individuals will be able to function normally on an average of 10 years following which many require the use of wheelchairs or other assistance.
The overall prognosis for individuals who have contracted HTLV-2, remains to be good. As of 2015, it was reported that almost 95 percent of individuals who contract this type of the virus are asymptomatic throughout their lives.
Will I need regular screening?
Individuals with HTLV should be regularly screened for the various health conditions that HTLV can lead to. You will not need to be regularly screened for the HTLV virus itself, as the virus is lifelong. Therefore, once you have tested positive, you will always test positive.
Will my children also get HTLV?
There is a small risk of HTLV being transmitted from mother to child. The transmission mainly occurs at the time of childbirth and breastfeeding.
Can I still have sex?
Yes, you can still safely have sex with a condom. Although it is advised to remember that condoms are not 100% effective and may split or tear resulting in a risk of exposure for your partners.
Can I still donate blood?
If you have tested positive for HTLV you will not be allowed to donate blood.
How can HTLV affect me during pregnancy?
In most women HTLV will not affect the course of pregnancy unless they have developed other complications from the infection. Obstetricians may consider offering a caesarean section to minimise the risk of transmission to the newborn.
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Page reviewed by Dr. Manoj Malu (Clinical Director)
With assistance from Shannon Abraham
Last reviewed date: 12 January 2023
Next review due: 12 January 2023
Whilst this content is written and reviewed by sexual health specialists, it is for general guidance only. It is not intended to replace the advice of your clinician.
References & Further Reading
- News-medical: What are T Cells?.
- UK NSC: HTLV
- National Centre for Retrovirology: HTLV-1
- GOV.UK: Human T-cell lymphotropic virus (HTLV) types 1 and 2
- WHO: Human T-lymphotropic virus type 1
- HRF: HTLV Blood Test Results Explained
- Vitalant: HTLV-I/II Information Sheet
- Health direct: HTLV-1 infection
- WHO: Human T-lymphotropic virus type 1
- National Centre for Human Retrovirology: HTLV-1