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The Human T-cell lymphotropic viruses (HTLV) are a group of viruses including HTLV-I, -II, and -III. HTLV-III viruses are also known as human immunodeficiency viruses (HIV), with HIV-1 and HIV-2 subtypes causing acquired immunodeficiency syndrome (AIDS). However HTLV-I is a very different virus, and does not cause AIDS. HTLV-I is endemic in many countries, principally Japan, the Caribbean and central Africa. It is also found in Iran, Iraq, southern India, China, the Seychelles, Papua New Guinea, the Solomon Islands and Australia. It is estimated that 10 to 20 million people around the world are infected by HTLV-I.
In Australia the virus occurs in many Aboriginal populations, having been found as far apart as the Kimberley and Cape York, but its prevalence varies markedly. In Central Australia the prevalence of HTLV-I is estimated to be up to 14% and even higher in some small remote communities. In non-Aboriginal Australians the virus is rarely detected, unless the person comes from one of the high-risk populations. HTLV-I is spread via breast milk, sexual contact, IVDU, with other transmission via transplacental mother to child being less frequent.
Effects of HTLV-1 infection
About 1 in 20 people infected with HTLV-1 develop ATL - adult T-cell leukaemia/lymphoma, a form of cancer of T-lymphocytes. There are several subtypes of ATL which affect people differently. It can affect the blood (leukaemia) or the lymph nodes (lymphoma).
Adult T-cell leukaemia/lymphoma develops:
- in approximately 1 in 40 people who are infected with HTLV-I
- mostly in people who became infected as a baby
- usually decades after the infection is acquired
Some types of adult T-cell leukaemia/lymphoma develop very quickly while others develop much more slowly.
Symptoms typically include:
- swollen lymph nodes
- fatigue
- skin rash
- nausea and vomiting
- fevers and sweats
HTLV-I associated myelopathy/tropical spastic paraparesis
About 1 in 100 people with HTLV-1 infection will develop HTLV-1 associated myelopathy, also known as tropical spastic paraparesis (HAM/TSP) a chronic disease of the nervous system that affects the spinal cord. It usually affects only people who are over 40 years.
Symptoms include:
- progressive muscle weakness in the legs
- muscle stiffness and spasma
- lower back pain
- inability to control their bladder or bowels
HAM/TSP usually has a slow onset and progresses slowly over time. Initial symptoms are subtle and include gait problems, unexplained falls, lower back pain, constipation, urinary urgency/incontinence and numbness or pain in the lowe limbs. Over the years, progressive leg weakness ensues followed by worsening of the urinary and sensory symptoms. The prognosis of HAM/TSP is variable, while some patients can still weak after one or two decades of disease, others may be confined to a wheelchair only a few months after onset of disease.
Other HTLV-associated conditions
HTLV-1 infection can also cause other conditions that affect the skin (dermatitis), eyes (uveitis), and muscles (polymyositis, arithitis). These associations, and other postulated associated conditions of the thyroid, lungs and cervix are less clearly due to HTLV-1.
HTLV-II associated condtions
HTLV-II infection is less clearly associated with diseases, and infection with this virus is not currently clearly a cause of conditions found associated with HTLV-1. However, studies are starting to suggest HTLV-II infection may be associated with neurologic problems including HAM/TSP, albeit at a much lower rate than the association with HTLV-1.
How is HTLV-1 Transmitted?
HTLV-1 is transmitted from mother to child mainly through breast feeding. About 20-50% of the babies born to infected mothers will become carriers. Other ways the disease is passed on are by blood transfusion (if the blood is not screened for HTLV-1), sexual intercourse and by sharing contaminated needles. HTLV-1 cannot be tramsitted through social contact with infected people such as shaking hands, hugging, kissing or drinking from the same glass.
HTLV tests
Blood specimens are initially tested for the presence of antibodies to HTLV-1. More specific confirmatory nuclei acid tests can also be performed. In Australia at present HTLV testing is only done on a large scale by blood banks ( see below under Prevention), and screening of organ and tissue donors. Currently HTLV testing is not subsidised by Medicare but this is under review as part of a strategy being developed to reduce the number of new cases in Aboriginal and Torres Strait Islander communities. Outside othe endemic areas in centrali Australia there is little need for testing as the prevalence is extremely low. The presence of antibodies to HTLV-1 indicates that a person is infected with the virus. Infection is lifelong.
Related pages
On this site
HIV
Elsewhere on the web
Healthdirect – HTLV-I
NT Government – HTLV-I
National Organization for Rare Disorders – HTLV-I and II
HTLV aware
Treatment
There is currently no treatment for chronic HTLV-1 infection. Treatment of ATLL with conventional combination chemotherapy has generally provd disappointing. No specific treatment is known for HAM/TSP but some of the symptoms can be lessened by medications.
Prevention of infection
Transmission by breast milk can be prevented by bottle feeding infants of infected mothers, although in many communities the risks associated with bottle feeding need to be weighed against the risks of HTLV-1.
Persons infected with HTLV-1 should refrain from donating blood, semen, body organs, or other tissues. In January 1993, the Australian Red Cross instituted universal screening of all blood donations for HTLV-1 and II antibodies.
People with HTLV-1 infection should use condoms to help prevent sexual transmission to a negative partner. Male-infected, female-non-infected couples desiring pregnancy shoud be made awre of the finite risk of sexual transmission of HTLV-1 during attempts at pregnancy and of the small risk for vertical transmission from mother to infant unrelated to breast-feeding.
Last Review Date: November 27, 2018
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