Tropical spastic paraparesis human T leukemia virus type 1-associated myelopathy in HIV type 1-coinfected patients

Background. Tropical spastic paraparesis/human T leukemia virus type 1 (HTLV- 1) - associated myelopathy (TSP/ HAM) is rarely reported in the United States. The causative agents of TSP/ HAM are HTLV-1 and, possibly, its cosmopolitan variant, human T leukemia virus type 2 (HTLV- 2). Among HTLV-1- or HTLV-2-monoinfected individuals, The estimated lifetime risk for development of TSP/ HAM is < 2%. However, it has been suggested that HIV/HTLV coinfection may increase the risk for development of TSP/ HAM. Methods. A total of 2239 human immunodeficiency virus (HIV) - infected patients were tested for HTLV-1 and HTLV-2 infection at the New Orleans Outpatient Clinic ( Louisiana) during the period 1991 - 1998. HTLV-1 infected patients with suspected myelopathy were referred for additional evaluation. Results. Four cases of TSP/ HAM (9.7%) were identified among 41 individuals with Western blot - confirmed HTLV- 1 infection. The diagnosis was confirmed with use of molecular diagnostic assays and viral isolation. No TSP/ HAM cases were identified among 65 patients with HIV - HTLV- 2 coinfection. An additional patient with HIV - HTLV- 1 coinfection also received a diagnosis of TSP/ HAM at the New Orleans Veteran's Affairs HIV Outpatient Clinic (Louisiana). All patients had normal CD4(+) T cell counts at the time of diagnosis. Conclusions. Given the high rates of HIV-HTLV coinfection in the United States, a heightened suspicion for TSP/ HAM should be considered in HIV-infected patients who present with normal CD4(+) T cell counts and myelopathy in the absence of other acquired immunodeficiency syndrome - defining conditions.