Human metapneumovirus infection in haematopoietic stem cell transplant recipients: a case series

Human metapneumovirus (hMPV) is an enveloped virus that causes serious respiratory tract infection among immunocompromised populations especially haematopoietic stem cell transplant (HSCT) recipients. Here, we describe 3 cases of hMPV infection which led to mortality among post HSCT adults. 66 post HSCT adults enrolled between January 2017 and March 2019 at Dr. B. R. Ambedkar Institute Rotary Cancer Hospital, AIIMS, New Delhi, were followed up for a period varying from 16 days to 18 months for any episode of respiratory illness until March 2019. Real time reverse transcriptase polymerase chain reaction (rRT-PCR) was used to detect the virus from appropriate specimens when symptoms of acute respiratory infection appeared. Samples from 88 out of a total of 172 episodes of suspected acute respiratory infection could be tested by rRT-PCR. Of these, 9 episodes were positive for hMPV. Three patients with hMPV associated lower respiratory tract infection (LRTI) expired within 30 days of HSCT. The possible risk factors associated with mortality included LRTI, infection during early post-transplant period (first week following HSCT), absolute lymphocyte count less than 200/µl, absolute neutrophil count less than 500/µl, use of steroid within 30 days prior to infection and need for mechanical ventilation.