Human metapneumovirus in haematopoietic stem cell transplantation recipients: a case series and review of the diagnostic and therapeutic approach.

Human metapneumovirus (hMPV) is a paramyxovirus that causes respiratory tract infections ranging from mild upper airway infection to severe pneumonia. Patients with haematological disease, especially haematopoietic stem cell transplantation (HSCT) recipients, are more likely to develop more severe infections. We describe three cases of hMPV infection in HSCT patients. The most reliable diagnostic procedure for hMPV is multiplex ligation-dependent probe amplification (MLPA) on a nasopharyngeal swab. Sensitivity and specificity of MLPA to detect hMPV is high and time to diagnosis is short. A number of other respiratory pathogens can be tested in one test run. Treatment is mainly supportive and only a few antiviral agents are available for treating paramyxovirus infections. Ribavirin and immunoglobulins were reported to be effective in cases of HSCT patients with hMPV pneumonia but their efficacy has not been studied in randomised trials.