Infections that can mimic childhood Connective Tissue Diseases
• Acute rheumatic fever: Rare before the age of 4 years. Severely painful, migratory polyarthritis with fever
• Parvovirus infection: Young children get erythema infectiosum (“slapped cheeks”). Older children and adults can get fever (50%), polyarthritis, and rash. Can mimic systemic or polyarticular JIA. IgM antiparvovirus antibodies can be negative for first 2 to 3 weeks, but polymerase chain reaction for parvovirus B19 DNA will be positive. Arthritis can last over 4 months (50%)
• Epstein–Barr virus infection: Can mimic SLE. Monospot negative in children aged <4 years. Diagnose with IgM antibodies to viral capsid antigen and negative antibodies to Epstein–Barr nuclear antigen during initial acute infection.
• Immunodeficiency: Humoral and combined immunodeficiency can present as infections including septic joints. Echovirus can cause a myositis and mycoplasma a chronic monoarticular arthritis. Consider immunodeficiency in any child with history of two previous bacterial pneumonias
• Lyme disease: Can mimic oligoarticular JIA May start out as migratory arthritis. May cause morphea-like lesions.
• Human immunodeficiency virus infection: Can present as muscle, skin, or joint problems in children. Generalized adenopathy, fever of unknown origin with organomegaly, and thrombocytopenia are other presentations