M Mijiyawa, O Oniankitan, M A Khan
Published: July 2000
“HLA-B27 is virtually absent in most of the sub-Saharan Africa populations, and ankylosing spondylitis is rare; only a few patients have been reported from central and southern Africa.
HLA-B27 was present in only one of 17 patients (6%) [of those who with ankylosing spondylitis, not the total population].
The disease shows clinical features that are similar to those observed in white HLA-B27-negative patients with ankylosing spondylitis; i.e. the disease onset is later compared with HLAB27-positive patients, the patients rarely get acute anterior uveitis as one of the extra-articular manifestations, and familial occurrence of ankylosing spondylitis is rarely observed.
There is a virtual absence of ankylosing spondylitis even in the west African countries of Gambia and Senegal, where 3% to 6% of the general population has HLA-B27.
The epidemic of HIV infection in sub-Saharan Africa in recent years, however, has been associated with a dramatic upsurge in the prevalence of spondyloarthropathies other than ankylosing spondylitis, primarily reactive arthritis and undifferentiated forms of the disease, and less often psoriatic arthritis.
HLA-B27, because of its rarity and virtual lack of association with the observed cases of spondyloarthropathy in this population, cannot be used as an aid to diagnosis of spondyloarthropathy in black Africans.
Conversely, HIV infection is increasingly showing such a strong association with reactive arthritis, psoriatic arthritis, and undifferentiated spondyloarthropathies in sub-Saharan African populations that any patient with acute or chronic inflammatory arthritis may need to be tested for possible HIV infection.
More research is needed on the evaluation of risk and protective factors in sub-Saharan African populations to better delineate the relative importance of genetic and environmental factors in the pathogenesis of spondyloarthropathies.