Rubella and parvovirus B19 (B19V) infections can present with arthritis-like symptoms in adults instead of typical dermatological symptoms. We quantify associations between rubella and B19V, respectively, with arthritis-like complications using real-world diagnostic testing.

Cross-sectional and retrospective cohort study.

Reference laboratories across the USA.

Participants with IgM tests for rubella (N=211 917) or B19V (N=644 473) performed at Labcorp from 2014 to 2023. Among these participants, participants with IgM tests for rubella (N=1867) or B19V (N=22 683) and longitudinal laboratory testing through Labcorp were followed for diagnostic tests for rheumatoid arthritis (RA) up to 1.5 years after the viral IgM tests.

Primary outcomes were arthritis-like suspicions by providers and diagnostic testing for RA-associated biomarkers.

Higher proportions of suspicions of arthritis (1.4%, p

Increased awareness of non-typical RA symptoms may facilitate differential diagnosis between rubella, B19V and RA. Recent B19V infections do not occur concurrently with RA; recent B19V infections should be considered in the differential diagnosis for RA when patients present with polyarticular joint symptoms.