Human metapneumovirus infection in an immunocompetent adult presenting as mononucleosis-like illness.

A 37-year-old man was presented with incidental findings of neutropenia, atypical lymphocytosis, thrombocytopenia and deranged liver parenchymal enzymes. Four days later, he developed fever, sore throat and cervical lymphadenopathy, compatible with mononucleosis-like illness (MLI). Polymerase chain reaction (PCR) and viral culture of the nasopharyngeal swab showed human metapneumovirus (hMPV). There was a >/=4-fold rise in IgG against hMPV. This is the first case report illustrating the natural clinical course of hMPV-related MLI.