Human retroviruses HTLV-I, HIV-1, and HIV-2 and neurological diseases in some equatorial areas of Africa

HTLV-I is associated with tropical spastic paraparesis (TSP) in the Caribbean area and with certain chronic myelopathies termed HAM (HTLV-I-associated myelopathy) in Japan. In order to investigate the situation in Africa, we tested for HTLV-I, but also for HIV-1 and HIV-2 antibodies, 94 patients with epidemic spastic paraparesis (ESP) from Zaire and Tanzania, 26 cases of sporadic spastic paraparesis (SSP) and 21 cases of tropical ataxic neuropathy (TAN), both from Ivory Coast, and 319 unselected neurological patients from Ivory Coast, Congo, and Tanzania. While none of the 94 ESP cases nor any of the 21 TAN patients exhibited antibodies to any retrovirus, 4 of the 26 sporadic spastic paraparesis patients had high HTLV-I antibodies in their sera and cerebrospinal fluid (CSF). Three of those were clinically and immunologically identical to TSP, as observed in persons from the Caribbean region, and the fourth case, a poorly explored chronic pyramidal syndrome, could also represent a TSP. Only one of these four cases originally had HIV-1 antibodies. Among the 319 unselected patients, only 5 (1.6%) had HTLV-I antibodies, but 32 (10%) had HIV-1 antibodies and 14 (4.4%) had HIV-2 antibodies, with a number of combined infections, indicating that retroviruses represent potentially important etiological agents for African neurological diseases.