HTLV – Human T-lymphotropic virus
What is HTLV?
Human T-lymphotropic virus, or HTLV, is a rare virus with low infectivity that primarily targets blood cells. It is characterized by an exceptionally long incubation period, which can extend up to 30 years. There are currently two well-known variants of HTLV (I and II), with a third form recently identified. HTLV belongs to the deltaretrovirus group, which causes lifelong infections that the body cannot clear on its own. Historically, the term HTLV was used to describe what we now know as HIV; however, HTLV and HIV are distinct viruses. HTLV cannot lead to AIDS. There is a certain stigma associated with HTLV which can make it especially challenging for the individuals who are affected.
How is HTLV transmitted?
HTLV can be transmitted between people through sexual contact, breast milk, blood or other body fluids.
What symptoms can I get?
Most people never develop any symptoms, but a common symptom is pain, and a few people develop symptoms after many years, for example in the form of cancer of the lymphatic system, lymphoma or, in rare cases, via a spastic disease called HTLV-associated myelopathy, or tropical spastic paraparesis. These diseases are mainly associated with HTLV-1 and are very rare in Sweden. For HTLV-2, no specific disease association has been identified at present.
How is the examination and testing done?
Diagnosis is made using blood tests that detect the presence of HTLV in the body using specific antibodies. All newly detected cases should be referred to an infectious disease clinic for follow-up. Most cases of HTLV are diagnosed during screening of blood donors, and some cases are detected during tracing or investigation of disease associated with HTLV.
Where can you get tested?
You can get tested at any health center, family doctor’s office, youth clinic, skin and vein clinic, sexual and reproductive health clinic, and specialized clinics for sexually transmitted infections. You can find phone numbers and links to many of the clinics here.
How is HTLV treated?
There is no treatment to cure the infection, nor is there a vaccine to prevent infection. People living with HTLV are given special precautions to prevent further transmission. Condoms should be used during sexual contact.
How common is the disease?
In 2024, a total of 25 cases of HTLV infection (types I and II) were reported in Sweden.
What does the Infection Control Act say?
HTLV is classified as a generally dangerous disease according to the Swedish Infection Control Act. All cases must be reported to an infectious disease physician and to the Public Health Agency of Sweden.
