Spondyloarthritis in sub-Saharan Africa.

Spondyloarthritis (SpA) is generally uncommon in sub-Saharan Africa, in part because of the rarity of HLA-B27 in this region. However, the relationship between HLA-B27 and SpA, particularly ankylosing spondylitis (AS), is complex. Despite the HLA-B 27:05 risk allele occurring in some West African populations, associated AS is not seen. In fact, most patients with AS are HLA-B27-negative, although there is emerging evidence that another class I HLA molecule, HLA-B 14:03, is associated with AS in black Africans. The Assessment of SpondyloArthritis International Society criteria for detecting early axial disease are of limited value in sub-Saharan Africa, because of both the rarity of HLA-B27 and very limited access to magnetic resonance imaging. Reactive arthritis (ReA), psoriatic arthritis, and undifferentiated SpA are seen mainly in the context of HIV infection, although the exact effect of the virus in the pathogenesis of arthritis is unclear. In Zambia, ReA is associated with the HLA-B*57:03 allele, which is paradoxically also associated with slow progression of HIV infection. HIV-associated ReA has a more protracted and aggressive course than standard ReA. Enthesitis-related arthritis is more common in children infected with HIV by vertical mother-to child transmission. Use of TNF inhibitors for axial disease is problematic, mainly because of cost, but also because of potential safety problems, especially reactivation of tuberculosis.