Tropical spastic paraparesis associated with human T lymphotropic virus type I in an east African naturalised in Sweden

Geographic distribution, clinical epidemiology and genetic diversity of the human oncogenic retrovirus HTLV-1 in Africa, the world's largest endemic area

The African continent is considered the largest high endemic area for the oncogenic retrovirus HTLV-1 with an estimated two to five million infected individuals. However, data on epidemiological aspects, in particular prevalence, risk factors and geographical distribution, are still very limited for many regions: on the one hand, few large-scale and representative studies have been performed and, on the other hand, many studies do not include confirmatory tests, resulting in indeterminate serological results, and a likely overestimation of HTLV-1 seroprevalence. For this review, we included the most robust studies published since 1984 on the prevalence of HTLV-1 and the two major diseases associated with this infection in people living in Africa and the Indian Ocean islands: adult T-cell leukemia (ATL) and tropical spastic paraparesis or HTLV-1-associated myelopathy (HAM/TSP). We also considered most of the book chapters and abstracts published at the 20 international conferences on HTLV and related viruses held since 1985, as well as the results of recent meta-analyses regarding the status of HTLV-1 in West and sub-Saharan Africa. Based on this bibliography, it appears that HTLV-1 distribution is very heterogeneous in Africa: The highest prevalences of HTLV-1 are reported in western, central and southern Africa, while eastern and northern Africa show lower prevalences. In highly endemic areas, the HTLV-1 prevalence in the adult population ranges from 0.3 to 3%, increases with age, and is highest among women. In rural areas of Gabon and the Democratic Republic of the Congo (DRC), HTLV-1 prevalence can reach up to 10-25% in elder women. HTLV-1-associated diseases in African patients have rarely been reported in situ on hospital wards, by local physicians. With the exception of the Republic of South Africa, DRC and Senegal, most reports on ATL and HAM/TSP in African patients have been published by European and American clinicians and involve immigrants or medical returnees to Europe (France and the UK) and the United States. There is clearly a huge underreporting of these diseases on the African continent. The genetic diversity of HTLV-1 is greatest in Africa, where six distinct genotypes (a, b, d, e, f, g) have been identified. The most frequent genotype in central Africa is genotype b. The other genotypes found in central Africa (d, e, f and g) are very rare. The vast majority of HTLV-1 strains from West and North Africa belong to genotype a, the so-called 'Cosmopolitan' genotype. These strains form five clades roughly reflecting the geographic origin of the infected individuals. We have recently shown that some of these clades are the result of recombination between a-WA and a-NA strains. Almost all sequences from southern Africa belong to Transcontinental a-genotype subgroup.

Tropical spastic paraparesis/HTLV-I-associated myelopathy in Europe and in Africa: clinical and epidemiologic aspects

We review here the epidemiologic and clinical aspects of tropical spastic paraparesis, human T-cell lymphotropic virus type I (HTLV-I)-associated myelopathy (TSP/HAM) as observed in Europe and in Africa. Europe is not an endemic region for HTLV-I (seroprevalence in blood donors, < 0.03%), and TSP/HAM is thus rarely observed in European countries. Most of the few patients suffering from TSP/HAM are first- or second-generation immigrants from HTLV-I endemic areas (mostly the West Indies), and the clinicoepidemiologic aspects of these patients are similar to those seen in endemic areas. However, rare cases occur in European-born subjects with or without risk factors for HTLV-I infection, which raises the possibility of limited foci areas in Europe. Although Africa is considered as a primary HTLV-I endemic area, with at least a few million infected inhabitants, epidemiologic data on the situation of TSP/HAM in Africa remain scarce. Relatively few cases of patients with TSP/HAM have been reported in Africa, including some clusters in Zaire (prevalence, 50/100,000) and in South Africa and sporadically in the main cities of some Western, Central, and Eastern African countries. The paucity of clinical and epidemiologic data on TSP/HAM may be linked to several factors, including the paucity of neurologists, the lack of laboratory and radiologic facilities, and the chronicity of the disease, along with the limited number of field epidemiologic studies performed on this topic and the wide diversity of causes (toxic, nutritional, and infectious) of chronic myelopathies as seen on the African continent.

HTLV-II among injecting drug users in Stockholm

134 injecting drug users (IDUs) treated at the Department of Infectious Diseases of Roslagstull Hospital, Stockholm, were tested for antibodies to human T-lymphotropic virus, types I and II, by means of 2 HTLV-I/-II peptide-based enzyme immunoassays (EIAs), followed by a whole-virus EIA. Positive EIA reactions were checked and typed by electrophoretic immunoblotting with native HTLV-I and recombinant HTLV-I and -II proteins. 10 IDUs were diagnosed as HTLV-II seropositive. All 10 were of Scandinavian descent. Thus, like HIV-1, HTLV-II infection has entered the injecting drug user population in Stockholm.

Possible association of HTLV-I infection and dementia

We report a Swedish patient with progressive dementia possibly associated with human T cell-lymphotropic virus type I (HTLV-I) infection. The clinical investigation revealed no typical sings of other neurological disorders. The patient was probably infected in East-Asia 35 years before onset of the disease. High titers of specific HTLV-I antibodies were detectable with solid-phase peptide ELISA in serum (1:1.600) and cerebrospinal fluid (CSF) (1:20), and the CSF/serum anti-HTLV-I antibody ratio indicated intrathecal HTLV-I antibody synthesis. Western blot for HTLV-I and polymerase chain reaction with primers selected for the HTLV-I pol gene were positive in both peripheral blood and cerebrospinal fluid. HTLV-I antigen was also demonstrated after in vitro co-cultivation of mononuclear cells from peripheral blood. Thus, our findings indicate that HTLV-I infection also may be associated with dementia. In addition, this case report calls attention upon HTLV-I as a possible etiologic agent to neurological diseases in countries previously spared from the infection.

Neurological complications of endemic skeletal fluorosis, with special emphasis on radiculo-myelopathy

The results of surveys carried out between 1976 and 1985 in the fluorosis-endemic area of the Ethiopian Rift Valley is summarised, with emphasis on the neurological complications resulting from the crippling osteofluorosis. The neurological manifestations in the forms of myelopathy with and without radiculopathy (respectively 72% and 28%) occurred after exposure to high fluoride (greater than 4 ppm) for longer than 10 years. These deficits were clearly found to be a consequence of fluoride deposition in bones, resulting in generalised sclerosis and osteophytosis, with reduction in the diameter of the intervertebral foramina and of the spinal conal. Advanced osteosclerosis commonly causes severe spastic quadriparesis in flexion, accompanied by distressing spasms and urinary incontinence. The dilemma of these medical problems in relation to the agro-industrial economic developments of the Ethiopian Rift Valley is discussed.

A cluster of HTLV-1 associated tropical spastic paraparesis in Equateur (Zaire): ethnic and familial distribution

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.

HTLV-1 and tropical spastic paraparesis. 1. Clinical features, pathology and epidemiology

The clinical profile of tropical spastic paraparesis (TSP), described in scattered tropical and subtropical territories over the past 30 years, has been more clearly defined since the discovery of its direct association with human T lymphotropic virus type 1 (HTLV-1). A chronic disease of adults, commoner in women, it usually presents as a progressive spastic paraparesis with sphincter disturbance, sometimes with backache and lower limb sensory disorder. Most cases are chair-bound within 10 years. Histology reveals a chronic lymphocytic meningomyelopathy, predominantly in the spinal cord, together with long tract demyelination and hyalinoid thickening of the media and adventitia of small blood vessels. Geographical areas of high prevalence of TSP are known in the Caribbean, South America, South Africa, southern Japan, the Seychelles and probably in India, and it is sparsely endemic elsewhere. The virus appears to exist within lymphocytes for long periods. Vertical transmission occurs postnatally, and sexual and transfusion infection are also recognized, but much remains to be clarified regarding its pathogenesis and epidemiology.