Human T lymphotropic virus type I-associated myelopathy/tropical spastic paraparesis in São Paulo, Brazil.

We conducted a prospective clinical and epidemiologic evaluation of 45 cases of human T lymphotropic virus type I (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in São Paulo, Brazil. All enrolled patients had progressive chronic myelopathy and high titers of HTLV-I and HTLV-II antibodies, as determined by enzyme immunoassay and western blot. In 24 cases, the polymerase chain reaction (PCR) was performed so that HTLV-I could be distinguished from HLTV-II. The clinical and epidemiologic features of the patients from our study were similar to those of patients with HAM/TSP from other areas of endemicity for HTLV-I except that more patients in our study had received a blood transfusion prior to their illness. Despite the presence of HTLV-II virus in Brazil, all patients whose serum was tested by PCR were found to be infected with the HTLV-I virus.