Rheumatoid arthritis and connective tissue disorders: sub-Saharan Africa.

Rheumatoid arthritis (RA) once a rarity in Africa, is now reported in large numbers from many parts of Africa. Although epidemiological surveys have shown that the prevalence in urban populations is similar to Western communities, it is less common in rural areas. Further epidemiological studies are needed to confirm these findings in other parts of Africa and identify factors contributing to this difference to provide a better understanding for the emergence of RA in Africa. Earlier reports suggested that in African blacks RA was a mild disease, severe radiographic changes were uncommon, deformities were rare and extra-articular features were unusual and only symptomatic therapy was necessary to control symptoms in most patients. Recent experience shows that severe disease with deformities and radiographic changes are seen and a wide spectrum of extra-articular features are noted although they may be less common than in Caucasians. African blacks with RA may have a younger age of onset and the genetic association with HLA DR4 has been confirmed. Systemic lupus erythematosus (SLE) is also recognized more often in African blacks who have a younger age of onset. SLE is also recognized less often in males. Features such as photosensitivity and serositis are less common while renal disease is more common. A reported short-term mortality of about 30% emphasizes the need for urgent efforts to improve the prognosis in SLE. The infrequent occurrence of localized systemic sclerosis and the absence of anti-centromere antibodies in blacks was noted in a recent large series of patients with systemic sclerosis. The other connective tissue diseases and systemic vasculitides are reported much less frequently and will probably be detected more often in future. Anti-cardiolipin antibodies are detected frequently in association with infections, including HIV infection. The spectrum of diseases associated with ANCA includes a variety of connective tissue diseases and infections such as HIV infection and invasive amoebiasis must be added.