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We report on a neuropathological analysis of two cases of TSP/HAM originating from Brazil. These two cases had, respectively, an evolution of 13 and 40 years. The main neuropathological findings consisted of spinal cord atrophy, mainly the lower thoracic cord, diffuse degeneration of the white and grey matter, rare foci of mononuclear and perivascular cuffs, and hyaline hardening of arteriolae. The supraspinal structures were normal, excepting for a slight gliosis in the cerebellum. An analysis on the long evolutive cases as described in the literature is outlined in this study.

A type-specific serological survey among 1042 random nonneurological outpatients in two cities in the state of Ceara (northeastern Brazil) shows a low prevalence of HTLV-I (0.34% in Fortaleza; 0.44% in Crato) and of HTLV-II (0.34% in Fortaleza; 0% in Crato). Among 62 chronic myelopathic patients seen in Fortaleza 27 patients were found with clinical features of tropical spastic paraparesis (TSP); 10 of 27 were found HTLV-I seropositive (37%; 95% confidence limits, 19-58%). Proviral genome detection by polymerase chain reaction in 5 seropositive and 12 seronegative patients confirmed the serological findings. This excludes HTLV-I or -II infection as a cause in the seronegative TSP patients. The HTLV-positive and -negative patients did not differ clinically and by history, except that seropositives had a longer mean disease duration, a female predominance, and a higher proportion of white Caucasians. In this population with low HTLV-I and HTLV-II prevalences, HTLV-negative TSP is at least as frequent as the HTLV-I-associated TSP.

Tropical spastic paraparesis (TSP) is a chronic progressive myelopathy and in most of the cases has a retroviral (HTLV-1) etiology, when it is denominated HTLV-1 associated-mielopathy (HAM/TSP). Around 433 cases of TSP have been described in Northeast and Southeast Brazil. Among these cases, 157 (36.2%) are HTLV-1 positive and 276 (63.7%) are negative. Their mean age is 43.8 years with a slight predominance of females and mulattoes, although white patients are also numerous. Clinically all patients exhibit a spastic paraparesis with variable sphincter and sensory disturbance. Pain and autonomic symptoms seem to be expressive in the HTLV-1 positive HAM/TSP Brazilian patients.

The tropical spastic paraparesis (TSP) is a chronic myelopathy, predominant in the tropics, recently known to be of retroviral origin (HTLV-I). This paper aims at delineating the clinico-etiological evolution of this entity. The historical analysis of it showed that the TSP has had, along decades, many different denominations and the discovery of the retroviral origin for some of them has stimulated new paths of research and epidemiological interest in the tropics and Brazil.

A case of HTLV-1 associated tropical spastic paraparesis is described in a Belgian nun who had been working as a midwife in Central Africa. Occupational exposure was the only risk factor identified. Among 2,482 Belgian expatriates in tropical countries, 92% of whom had resided in sub-Saharan Africa for an average of 15.5 years, only one Belgian-born man was found seropositive for HTLV-1. He was married to an African woman and living in Central Africa for 23 years. The risk of HTLV-1 infection is low in Belgian expatriates and on its own does not support generalised anti-HTLV screening in autochthonous Belgian blood donors.

In Lisala (Equateur region, Zaire), where a cluster of tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM) was described, 28/200 (14%) out-patients and hospital personnel were HTLV antibody positive. No differences in prevalences were observed between out-patients and hospital personnel or between ethnic groups. The annual attack rate of TSP/HAM is estimated at 0.15-0.3 per 1000 infected. The ethnic and familial clustering of TSP/HAM together with the high attack rate suggests the presence of co-factors for the progression to disease. This high prevalence of HTLV antibodies contrasts with the low prevalence in another part of the Equateur region.

In Lisala, Equateur province, Zaire, 25 patients from 21 pedigrees were identified with human T-lymphotropic virus type 1 (HTLV-1) associated tropical spastic paraparesis (TSP). In the 10 (48%) pedigrees with additional genuine TSP cases established mainly by history, seven of 10 patients' mothers, no fathers or spouses, one of 59 surviving offspring, five of 105 siblings, and six other close blood relatives had TSP. A child may develop TSP before its mother. Three familial cases were in paternal relatives only. In total, 39 cases (11 men, 28 women) were identified in this population of about 50,000. Half were in the Mundunga minority of less than or equal to 10% (p less than 0.001). The data suggest maternal transmission of HTLV-1 and enhanced TSP susceptibility in those infected due to familial, probably genetic factors.