What is the Human T-Lymphotropic Virus 2?
The human T-lymphotropic virus 2 is also called HTVL-2 for short. This is a so-called retrovirus, which predominantly infects the CD8-positive T lymphocytes. The connection between the virus and the development has not yet been clearly proven. In some affected individuals the virus leads to T-cell lymphomas and also to neurological diseases.
What is the morphology of human T-lymphotropic virus 2?
The genome of HTVL-2 consists of RNA and comprises about 8500 bases. It shows a great similarity to the morphology of HTLV-1. The genome is transcribed into a double-stranded DNA by transcriptase. At the end of the virus there are two identical flanking sequences and there are 3 gene regions in between.
How widespread is the human T-lymphotropic virus 2?
It is not known how many people are infected with the virus. However, estimates the number of people affected to be much lower than with HTLV-1 with 15-20 million worldwide or even HIV with more than 40 million infected worldwide. Especially in western countries like the USA, the virus is increasingly found among drug addicts. However, quite isolated peoples also have a high prevalence, including among others:
- Guamyì in Central America,
- Guahibo and Kayapó in the Amazon basin in Venezuela or Brazil,
- Pygmies in Equatorial Africa,
- melanesian populations on certain islands in the Pacific or in the highlands of Papua New Guinea.
In
Europe, human T-lymphotropic virus 2 is hardly ever encountered
. Therefore, blood donors in Germany are not routinely tested for the virus, unlike those
in the USA.
The following three main transmission routes are known:
- a postnatal infection of an infant through the breast milk of an infected mother.
- through infected blood products that are passed on via transfusions.
- through sexual contact.
What are the symptoms of human T-lymphotropic virus 2?
At the present time, no clear correlations between a disease and HTLV-2 are known. However, there are some symptoms and diseases that can be suspiciously associated with HTLV-2 . These include:
- Sensory neuropathies,
- Mycosis fungoides (special form of T-cell lymphoma),
- Chronic lung infections such as bronchitis, pneumonia, etc.,
- COPD,
- Motor symotoms.
Meanwhile
, T-cell leukaemia and neuromuscular syndromes are provable as
sequelae similar to HTLV-1 infection. They are considered the
two most severe diseases for which HTLV-2 is causative.
The adult T-cell leukaemia: This is a very aggressive form of the non-Hodgkin lymphoma. The acute form of the disease leads to the death of the patient within a few months in most cases. Characteristic are the itchy, livid skin lesions. There may also be infections of the entire body, i.e. organs, nerves as well as bones .
Tropical spastic paraparesis: The focus of this disease, which is triggered by HTLV-2, is particularly on neurological changes. These include urinary and faecal incontinence, back pain and paraparesis. Other possible symptoms include uveitis, keratoconjunctivitis and arthritis.
How is human T-lymphotropic virus 2 diagnosed?
The diagnosis must be made on the basis of examination results of the cerebrospinal fluid, EDTA blood, bone marrow, skin biopsies and/or lymph node tissue . Primarily, HTLV-2 can be detected by means of PCR tests.
If an infection with the virus can be detected, the following prohibitions apply:
- No blood donations or organ donations may be made by the infected person.
- It is compulsory to provide information about the practice of unprotected sexual intercourse.
- A mother should not breastfeed her infant, but feed it with infant formula.
How is human T-lymphotropic virus 2 treated?
With chemotherapy and antiretroviral drugs, a viral load can be significantly reduced. However, the benefit of these therapeutic measures, apart from the lower risk of infection, is not known to date .
How can human T-lymphotropic virus 2 be prevented?
At the present time, there is still no vaccination against HTLV-2 and there will probably be no research into developing a suitable vaccine against it in the near future. First and foremost, the virus is transmitted via the bloodstream, which means that one should avoid unprotected sexual contact. The use of condoms is still the most effective way to protect yourself from infection. Mothers who are infected with the virus should not breastfeed their babies but use bottle feeding. Drug users are also among the particularly vulnerable groups, especially if they share syringes and needles with others. Therefore: Everyone should use their own hypodermic needles and syringes.
What is the prognosis for diseases caused by human T-lymphotropic virus 2?
More than 95 per cent of those infected never experience symptoms. However, the disease seems to be associated with a slightly higher mortality rate, than other viral infections. If acute T-cell leukaemia is present, where the focus is not on the skin but on the leukaemia, the survival rate is less than 1 year after diagnosis. If tropical spastic paraparesis is present, the prognosis is much better. In this case, the disease and death are associated much less frequently.
Is there an obligation to report human T-lymphotropic virus 2?
According to the Infection Protection Act, there is no obligation to report human T-lymphotropic virus 2.