Snapshot A 25-year-old woman presents to the emergency room for painful joints. She has had pain in her bilateral hands and wrists for the past few days. She also had a low-grade fever and mild upper respiratory symptoms. She is 14-weeks pregnant and has had good prenatal care. She works as a kindergarten teacher. On physical exam, the joint in her hands are slightly swollen and tender. A fetal ultrasound shows hydrops fetalis. Introduction Classification parvovirus B19 non-enveloped, linear, single-stranded DNA virus causes a variety of diseases aplastic crisis in patients with red blood cell disorders pure red blood cell aplasia in adults rheumatoid arthritis-like symptom in adults erythema infectiosum (fifth disease) in children hydrops fetalis in fetuses if pregnant women are infected transmission via respiratory droplets Epidemiology incidence highest in winter and spring demographics children > adults risk factors sickle cell disease thalassemia hereditary spherocytosis close proximity to others (e.g., school or daycare centers) Pathogenesis infects red blood cells through the P antigen viral replication in bone marrow causes the death of erythroid progenitor cells causes hydrops fetalis in fetuses due to severe fetal anemia Presentation Symptoms prodrome with flu-like symptom hydrops fetalis and fetal death in pregnant women polyarthropathy small joints (e.g., hands) Physical exam erythema infectiosum first rash appears as slapped cheeks subsequent rash is an erythematous maculopapular rash on the trunk and limbs, which may appear reticular or lacy Studies Labs parvovirus-specific immunoglobulin M detection of parvovirus on polymerase chain reaction anemia low or absent reticulocyte Making the diagnosis based on clinical presentation may be confirmed with laboratory studies Differential Measles distinguishing factors confluent maculopapular rash without slapped cheeks rash Koplik spots on buccal mucosa Rubella distinguishing factor non-confluent maculopapular rash that spreads from face to body Treatment Management approach mainstay of treatment is supportive care Conservative supportive care indication all patients modalities analgesics hydration Medical non-steroidal anti-inflammatory drugs indication polyarthropathy Complications Myocarditis Behcet syndrome Aplastic crisis