RHEUMATIC DISEASES IN AFRICAN BLACKS

Contrary to previous belief, there is increasing evidence that a broad spectrum of rheumatic diseases do affect African blacks. Although pro perly conducted epidemiological studies have yet to be performed, repo rts of population surveys from a variety of sub-Saharan African countr ies indicate that diseases such as rheumatoid arthritis (RA), gout, an d the connective tissue diseases are observed, although some differenc es in clinical presentation may occur as a result of cultural, racial, and socioeconomic factors. Rheumatoid arthritis is common in some par ts of Africa and less common in others. In particular, a significantly lower prevalence of RA in rural areas compared with urban cohorts has led to the hypothesis that environmental factors associated with urba nization may be involved in disease pathogenesis. A similar hypothesis has been suggested for hyperuricemia and gout. Clinical features of d isease may also be different in Africans when compared with other popu lation subgroups such as with systemic lupus erythematosus although th is may be artefactual as different accessibility to health care and re ferral practices may result in only the more severe cases coming to me dical attention (eg, lupus nephritis). Immunogenetic factors may reduc e the prevalence of some conditions such as the spondyloarthropathies. Although the association between HLA-DR4 and RA holds true in African s, the same is not so for the association of HLA-B27 with ankylosing s pondylitis (AS). The prevalence of HLA-B27 in African blacks is 10 tim es less than Caucasian populations, in part accounting for the low pre valence of spondyloarthropathies, although its association with AS is low. Other conditions such as human immunodeficiency virus (HIV)-relat ed arthopathies appear to be an increasing medical problem. The panepi demic of acquired immunodeficiency syndrome in Africa has resulted in an increased awareness of the different types of arthritis that may be associated with HIV. These are similar to those reported in other par ts of the world, although risk factors are different in Africa where h eterosexual transmission is a more common cause than homosexual transm ission or IV drug usage. Information on other rheumatic diseases such as osteoarthritis and soft tissue rheumatism are slowly emerging. Rheu matic manifestations of the infectious diseases, which are endemic in Africa, remain a uniquely fascinating aspect of rheumatology practice on the African continent. Therefore, African countries will increasing ly be a continued valuable source of clinical material for comparative studies to help elucidate factors that influence the development of r heumatic diseases.