Human T-cell lymphotropic virus type 1 (HTLV-1) - including symptoms, treatment and prevention

Human T-cell lymphotropic virus type 1 (HTLV-1) is a virus that infects a type of white blood cell called a T‐lymphocyte. HTLV-1 is a distant relative of the human immunodeficiency virus (HIV) which can cause acquired immunodeficiency syndrome (AIDS). HTLV‐1 does not cause AIDS.

HTLV‐1 is present in many areas including

  • principally Japan
  • the Caribbean
  • central Africa
  • Iran
  • Iraq
  • southern India
  • China
  • the Seychelles
  • Papua New Guinea
  • the Solomon Islands
  • Australia.

In Australia, the virus has been found in many Aboriginal populations in Central Australia as well as the Kimberley region in Western Australia. In Central Australia up to 50% of adults in some Aboriginal communities have the virus. In non‐Aboriginal Australians the virus is very uncommon but sporadic cases have been reported

How HTLV-1 is spread

HTLV‐1 can be spread from an infected person through unprotected sex, by sharing contaminated needles, by blood transfusion, and from a mother to her child (mainly through prolonged breast feeding).

Overseas studies have found the overall risk of spread by breast feeding is 20%, but the risk increases from around 5% at 6 months to more than 30% if infants are breast fed longer than 12 months. A few infants are infected before or during birth.

HTLV‐1 cannot be spread through social contact with infected people such as hand shaking, hugging, kissing or drinking from the same glass, nor can it be spread by coughing.

Signs and symptoms of HTLV-1

The majority of HTLV‐1 infected individuals will have no symptoms.

Two diseases have been definitely associated with HTLV‐1:

  • A type of cancer which affects the blood or lymph glands, called adult T‐cell leukaemia/lymphoma (ATLL)
  • A disease of the spinal cord which causes weakness similar to multiple sclerosis, called HTLV‐1 associated myelopathy/tropical spastic paraparesis (HAM/TSP).

Only a small proportion of people with HTLV‐1 will actually develop either of these two diseases.

People with HTLV‐1 infection may also have more severe infections with other organisms that cause disease, such as roundworm (strongyloidiasis) and scabies.

Incubation period

(time between becoming infected and developing symptoms)

Many years (10 to 40 years) before disease occurs.

Infectious period

(time during which an infected person can infect others)

Once a person has been infected with HTLV‐1 they remain infected for life and may be able to transmit the virus to others.

Diagnosis of HTLV-1

The diagnosis is made by the detection of antibodies to HTLV‐1 in a blood test, followed up by more specific tests to confirm the diagnosis.

Treatment for HTLV-1

No specific treatment is available for the HTLV‐1 virus, but treatment is available for some of the complications of the infection.

Prevention of HTLV-1

  • There is currently no vaccine to protect against HTLV-1 virus infection.
  • Spread by breast milk can be prevented by bottle feeding or freeze‐thawing breast milk from infected mothers. A doctor experienced in the management of HTLV‐1 infection should be consulted about ways to reduce spread to infants.
  • Persons infected with HTLV‐1 should not donate blood, semen, body organs, or other tissues. In January 1993, the Australian Red Cross started screening all blood donations for HTLV‐1.
  • HTLV‐1 infected persons should be educated that this virus can be spread sexually, and to use condoms to help prevent spread to a sexual partner who does not have HTLV‐1 infection. Couples planning a pregnancy should be made aware of the risk of sexual spread of HTLV‐1.

Useful links


Information modified and reproduced with kind permission from Northern Territory Centre for Disease Control. HTLV-1 Factsheet for patients and health professions.