This fact sheet gives basic, non-technical information about HTLV, and is based on an information sheet produced by St Mary's NHS Trust.
What is HTLV and where is it found?
Who gets HTLV, and how do they get it?
How do you know that you are infected with HTLV?
Does HTLV cause any disease?
Can HTLV infection and related diseases be treated?
How can you protect yourself and others against HTLV?
HTLV stands for human T cell lymphotropic virus, as it infects a type of white blood cell called a T-cell or T-lymphocyte.
There are two types of HTLV: HTLV-I and HTLV-II. They are retroviruses
HTLV-I is a very old virus, which appears to have infected and moved with humans for hundreds, if not thousands of years.
HTLV-I is endemic (common) in the Caribbean, Japan, South America, and parts of Africa.
HTLV-II is found among native Americans.
In England and Wales, HTLV-I is mainly found among people who originated from endemic areas and their families/sexual partners.
HTLV-II is not very common in England and Wales, and is found mainly, but not exclusively among injecting drug users.
HTLV-I and II can be transmitted from person to person in the following four ways. In England and Wales, the first three are mainly associated with HTLV-I and the last, with HTLV-II
From an infected mother to her baby. Up to 1 in 4 children born to mothers with HTLV-I infection become infected, with most infections occurring through prolonged breast feeding.
Between sexual partners through unprotected intercourse (no condom used). The risk of transmission from an infected man is greater than from an infected woman.
Through transfused blood from an HTLV infected donor. The risk of HTLV-I transmission through this route can be as high as 85%, depending on how the blood is handled and stored.
Through the sharing or re-use of needles and syringes to inject drugs.
HTLV infection is not passed from person to person by coughing, sneezing, kissing, cuddling or daily social contact.
Most people who are infected with HTLV are unaware of their infection as they are perfectly well.
These people are known as 'asymptomatic carriers', as they are infected, but have no signs or symptoms related to their infection.
HTLV infection can be detected by a specific blood test. This blood test detects HTLV antibodies that the body will produce shortly after becoming infected with HTLV, in order to fight the infection.
Infection with HTLV is lifelong, so the presence of HTLV antibodies shows that someone is infectious. The absence of HTLV antibodies means that a person is not infected, unless the infection has only just occurred and the test was done before the body had time to makeantibodies against the infection. If a recent infection is suspected, the blood test should be repeated three months later.
The great majority of people infected with HTLV do not develop any related disease.
A small minority of individuals, about 1 in 20 of these infected, will develop disease due to HTLV, but this usually occurs after several decades of infection.
There are two main types of disease caused by HTLV-I:
Adult T-cell leukaemia/lymphoma (ATLL): this is a rare form of cancer of the blood
HTLV-I-associated myelopathy (HAM): this is also known as tropical spastic paraparesis (TSP).
It is an inflammation of the nerves in the spinal cord that causes stiffness and weakness of the legs, backache, a 'weak' bladder and constipation.
Not all of these symptoms will be present, particularly at the beginning.
HTLV-I may also cause inflammation of the eye (uveitis), joints (arthritis), muscles (myositis), lung (alveolitis) and skin (dermatitis).
These conditions are less common than ATLL and HAM/TSP.
It is not so clear what diseases HTLV-II causes, but there is some evidence that HTLV-IIinfection is associated with neurological disease and less of an association with blood .disorders.
At present there is no treatment to eradicate HTLV infection from someone's body once infected.Infection with HTLV is lifelong.
As 95% of people infected with HTLV never develop any HTLV related symptoms, any treatment to eradicate infection would have to be very safe for its use to be justified.
ATLL is usually treated with anti-cancer drugs, but recently transferring to anti-viral treatment after starting with anti-cancer treatment has been shown to improve the outcome.
There are different medicines to treat the different symptoms that occur when someone has HAM/TSP.
HTLV is passed on via body fluids (blood, semen, vaginal fluids, breast milk) from an infected person, like HIV and the hepatitis viruses, and so the preventive measures listed below should prevent the transmission of all of these viruses.
Safer sex: any sexual contact which involves the transfer of body fluids from aninfected individual to anyone else carries the risk of spreading infection.
The degree of risk varies with activity. Using a condom reduces the likelihood of transmission of sexually transmitted infections.
Taking appropriate precautions when accidents involving blood spillage occur.
Household detergents and bleach are known to inactivate viruses.
Pregnancy and breast feeding: if a woman is known to be HTLV-infected, the chance of the baby also becoming infected can be reduced if breast feeding is avoided.
The single use of disposable equipment when injecting prevents transmission.