Respiratory Tract Reinfections by the New Human Metapneumovirus
The human Metapneumovirus (HMPV), a new member of the Paramyxoviridae family, has been recently associated with respiratory tract infections in young children. We report the case of a young, immunocompromised child who had severe lower respiratory tract infections during two consecutive winter seasons caused by genetically distinct HMPV strains.

A variety of viruses -- such as the influenza viruses A and B, the Human respiratory syncytial virus (HRSV), the parainfluenza viruses, and the adenoviruses -- cause seasonal respiratory tract infections in young children. Symptoms range from influenzalike illnesses to lower respiratory tract syndromes, such as bronchiolitis, croup, and pneumonitis. These viruses may also cause severe respiratory infections in immunocompromised patients. However, the cause of many cases of bronchiolitis and pneumonitis remains unknown despite the extensive use of sensitive diagnostic techniques.

The human metapneumovirus (HMPV) has been recently classified as a new member of the Paramyxoviridae family based on nucleic acid sequence, gene organization, and electron microscopy findings. This virus has been reported to cause respiratory tract infections in children <5 years of age from the Netherlands, as well as in elderly patients from North America. We describe a case of recurrent HMPV respiratory tract infections, associated with genetically distinct viral strains, in an immunocompromised child.