The first ASHM conference symposium on HTLV-1 proved extremely insightful, as to date I had very limited exposure and education related to it.
Numerous speakers provided comprehensive talks on this largely neglected topic. Two back to back session from Graham Taylor (imperial college London( and Fabiola Martin (University of Queensland) provided a great overview of the topic.
Like HIV, HTLV-1 is a retrovirus, however rather than triggering cell death, HTLV-1 triggers Tcells to proliferate. Where there is cell proliferation there is risk of mutations and malignancy. The virus is transmitted sexually, vertically and through blood exposure. 95% of those exposed are asymptomatic, however the virus may cause a HTLV-1 inflammatory syndrome characterized primarily by myelopathy. It also can eventually cause T cell leukemias/ lymphomas (emphasizing the importance of monitoring LDH and lymphocytes). Median age of onset of symptoms is 48, though its usually 7 years before patient present.
In terms of treatment steroids have shown improvement in the short term (though usually benefit does not persist beyond 4 wks. More recent studies suggest a role for steroid sparing agents with one showing at 48wks slight improvement in spasticity, walk tests, CSF VL and no increase in VL in the blood. Other more promising agents include AZT (for unclear reasons) in combination with interferon, and in Japan monoclonal antibodies to ccr4.
My take home message from this is in patients from endemic areas who present with a myelopathy, a HTLV-1 should be part of my routine work up.