Human metapneumovirus (hMPV) infection in immunocompromised children

Background Human metapneumovirus (hMPV) is a major cause of upper and lower respiratory tract infection (URTI, LRTI) in children. The prognosis of hMPV is unclear in immunocompromised patients. Objectives To describe the characteristics of hMPV infection in immunocompromised pediatric patients and to review the literature. Study design This retrospective study included 39 immunocompromised children (age 0–18 years) with proven hMPV infection attending two tertiary pediatric medical centers in 2004–2014. Demographic, clinical, laboratory, and radiological data were collected from the medical files. Results Median age was 6 years. Seven patients had primary immune deficiency and 32, secondary immune deficiency, including 9 patients who underwent hematopoietic stem cell transplantation (HSCT). Most cases (92%) occurred in January–May. Twenty patients (51%) had lower respiratory tract infection and 17 (44%), upper respiratory tract infection; 2 patients (5%) had fever only. Presenting symptoms were fever (70%), cough (54%), and rhinorrhea (35%). Severe lymphopenia (<1000 lymphocytes/mL) was noted in 64% of patients and elevated liver enzyme levels in 49%. Seventeen patients had pneumonia: bilateral and alveolar in 13 patients, each. HSCT was not associated with more severe disease. Respiratory failure occurred in 6 patients, of whom 4 died (10% of cohort). All children who died had severe lymphopenia. On multivariate analysis, bacterial or fungal co-infection was the only major risk factor for death. Review of the literature showed variable clinical presentations and severity in pediatric patients with hMPV infection. Conclusions Infection with hMPV may be associated with relatively high morbidity and mortality in immunocompromised children. Death was associated with bacterial and fungal co-infection.