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.