There is growing evidence that group A Streptococcus (GAS) infection of the skin, commonly causing impetigo, may initiate acute rheumatic fever (ARF) in a similar way to GAS infection of the throat. Additionally, impetigo in childhood may also prime the immune system making ARF more likely when subsequently exposed to GAS infection. We report on recent New Zealand (NZ) studies that investigate the role of GAS skin infection as a cause of ARF.
A paediatric case-control study of risk factors for ARF found that while most cases of ARF were preceded by a reported throat infection, some cases were preceded by only a skin infection. In addition, a record linkage study of 1.87 million throat and skin swabs linked to 835 cases of ARF found that the risk of ARF following a GAS infection was similarly elevated for both GAS skin and throat infections. Furthermore, GAS skin infections have a far more marked ethnic gradient than GAS throat infections, mirroring the much higher rates of ARF in Māori and Pacific children. Finally, samples collected as part of two case-control studies found significantly more type-specific GAS antibodies in ARF cases than controls and GAS skin infections induced an increased breadth of antibody responses compared with GAS throat infections.
These findings add support for prevention and treatment of skin infection in children to prevent ARF. A controlled trial could assess the impact of suitable skin infection interventions. The trial could use immune priming as an end-point requiring only a modest study size.