Human T-Lymphotropic Virus (HTLV) is a retrovirus associated with depression of the immune system. Several different retroviruses are classified in this family, including HTLV-I and HTLV-II. The differences between the various types are primarily related to their geographic distribution and the precise effects of the virus on the body. The virus is more common in the developing world, with several different blood tests available to detect the presence of its antibodies in the blood.
This retrovirus was first discovered in Japan in 1977, and it was isolated at the National Cancer Institute in the United States. Initially, early work on HIV, the virus that causes AIDS, classified HIV as a member of the HTLV family, and the virus was briefly known as HTLV-III. Additional research showed that HIV acted very differently from this other virus, however, and that it belonged in an entirely separate classification.
HTLV is linked with a number of health problems, including demyelinating diseases that affect the central nervous system, such as tropical spastic paraparesis, along with adult T-cell leukemia and lymphoma. Viruses in this group work by initially stimulating the immune system, which ultimately leads it to go into overdrive, at which point it starts attacking itself. As the immune system becomes weaker, the patient is at risk of opportunistic infections.
Once infected with HTLV, someone carries the infection for life. Treatment is primarily focused on managing the conditions associated with the virus, since no cure has been developed. In some cases, people may carry it without developing any symptoms, often passing it on to others because they are unaware. Other people develop cancers and other diseases, depending on the form with which they are infected.
This retrovirus can be transmitted in a number of ways. It is carried in blood and some bodily fluids, so instances of blood-to-blood contact, sexual contact, and shared needle use can result in its transmission. HTLV is also carried in breast milk. Widespread HIV/AIDS education often helps to reduce HTLV infection rates, as the same techniques used to reduce the risk of contracting both. In regions without adequate education or funds to provide preventative measures like needle exchanges and condoms, however, infection rates tend to remain consistent, or to increase.