Thyroid function in breast-fed infants whose mothers take high doses of methimazole.

INTRODUCTION: Human parvovirus B19 infection classically manifests as erythema infectiosum in children, but in adults the clinical spectrum is diverse and often atypical. While transient neutropenia and bone marrow suppression have been reported, mumps-like submandibular swelling is rarely described in immunocompetent adults.

CASE DESCRIPTION: We report a 38-year-old previously healthy man who presented with high fever and febrile neutropenia. Physical examination revealed pronounced bilateral submandibular swelling without parotid involvement. The patient's child had had a recent febrile illness, raising suspicion for mumps virus infection; however, serology for mumps antibodies was negative. Empiric therapy with intravenous meropenem was initiated. The patient's symptoms and neutropenia resolved promptly. Extensive evaluation for infectious and hematologic diseases was negative, but polymerase chain reaction for parvovirus B19 in blood was positive. The clinical course was favourable without complications.

DISCUSSION: This case highlights a rare presentation of acute parvovirus B19 infection in a healthy adult male, characterized by febrile neutropenia and mumps-like bilateral submandibular swelling. Although most adult parvovirus B19 infections present with arthralgia and rash, clinicians should consider parvovirus B19 as a differential diagnosis in adults presenting with unexplained neutropenia and salivary gland swelling, even in the absence of anaemia or typical rash. The possibility of parvovirus B19 should be especially considered when there is a history of contact with children displaying febrile illness. Early recognition may prevent unnecessary broad-spectrum antibiotic use and guide appropriate management.

CONCLUSION: Parvovirus B19 infection in immunocompetent adults can manifest with atypical features such as febrile neutropenia and submandibular gland swelling resembling mumps. A high index of suspicion and appropriate virological testing are essential for accurate diagnosis and management.

LEARNING POINTS: Parvovirus B19 infection can present atypically in immunocompetent adults, mimicking mumps with febrile neutropenia and submandibular swelling.Clinicians should include parvovirus B19 in the differential diagnosis of unexplained neutropenia accompanied by salivary gland enlargement.A recent history of contact with febrile children may provide a valuable clue to parvovirus B19 infection.