Reactivation of Parvovirus B19 Infection: An Uncommon Trigger of Macrophage Activation Syndrome in Adult-Onset Still's Disease.

A 40-year-old woman presented with four weeks of intermittent high-grade fever, cough, and joint pain, and two weeks of a generalized rash. She was found to have adult-onset Still's disease (AOSD) and rapidly developed macrophage activation syndrome (MAS) on the second day of admission. Among infectious etiologies, Epstein-Barr virus and members of the herpes virus family are common triggers of MAS. However, our patient was found to have reactivation/recurrence of parvovirus B19 infection as the cause; this is an uncommon trigger reported infrequently in the medical literature. Despite intensive treatment, the patient passed away.