The Re-emergence of Human Metapneumovirus: Virus Classification, Characteristics, Mechanisms of Infection, Clinical Features, Diagnosis, Epidemiology, Prevention, and Treatment

The respiratory virus known as the human metapneumovirus (HMPV) was discovered for the first time in 2001 in the Netherlands. It is a ribonucleic acid (RNA) virus that belongs to the Paramyxoviridae family. It causes upper and lower respiratory tract infections (RTIs), especially in young children and the elderly. Although the majority of HMPV infections are resolved on their own, some infected infants, children, and elderly patients need to be hospitalized. Patients with underlying immunodeficiency diseases, transplant recipients, and those with other co-morbidities, such as chronic diseases, are more likely to develop complications from HMPV infections, such as pneumonia. The symptoms of HMPV infections are similar to those of other viral RTIs caused by respiratory syncytial virus (RSV), influenza viruses, and coronaviruses. Differential diagnosis and identification of the etiological agents responsible for RTIs are crucial for improved patient care. Concerns of the next pandemic have been fueled by the discovery of the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of the coronavirus disease-2019 (COVID-19) that caused the pandemic, and the recent advent of other viral diseases like mpox. In addition, the World Health Organization (WHO) has emphasized the importance of public health readiness, as many pandemics are expected to occur. In light of this and a recent increase in HMPV cases signifying its potential re-emergence, we tried to thoroughly examine and update information on origin, transmission, pathogenicity, clinical features, laboratory diagnosis, epidemiology, prevention, and treatment of HMPV.