Introduction

Abstract

It is not uncommon for children and young people to present with evidence of joint inflammation and recent infection. Microorganisms can influence the development of arthritis through numerous mechanisms. The reactive arthritis syndrome classically refers to sterile joint inflammation, sometimes accompanied by extra-articular symptoms like uveitis, which manifests after recent infection of the gastrointestinal or genitourinary systems. Once the diagnosis is made, reactive arthritis can often be managed supportively as most children and young people experience quick resolution of their disease. A small proportion will continue with persistent arthritis and may evolve into a phenotype of enthesitis-related arthritis (a subtype of juvenile idiopathic arthritis) or juvenile ankylosing spondylitis. Important differential diagnoses include the Streptococcus-associated arthritides and Lyme disease, both of which respond to antibiotic treatment. In this review we summarize the latest developments in the understanding of reactive arthritis aetiology (including the roles of the human leucocyte antigen B27 genotype and the microbiome) and highlight the key features to help clinicians identify reactive arthritis and other post-infectious arthritides.