From the Guidelines
Human metapneumovirus (HMPV) is a paramyxovirus that causes upper and lower respiratory tract infections, particularly in children and adults during winter, with a diagnosis rate of 2.5% to 9% in the first 2 years after allogeneic HSCT. According to the study published in Clinical Infectious Diseases 1, HMPV infection is commonly diagnosed by NAT, and rates range from 2.5% to 9% during the first 2 years after allogeneic HSCT. The virus is closely related to RSV and can cause increases in URTID and tracheobronchitis in 5%–20% of children and adults.
Some key characteristics of HMPV include:
- Asymptomatic and prolonged shedding has been reported in HSCT patients 1
- HPMV URTID in HSCT patients can present with flu-like symptoms 1
- In HSCT patients with pneumonia, HMPV is frequently codetected with other pathogens, including bacteria, fungi, and other CARVs, as well as cytomegalovirus, which can obscure the attributable morbidity 1
- Recipient cytomegalovirus seropositivity was a risk factor in one study of HSCT patients 1
- Single cases of severe disease and fatal outcome have been reported 1
No general recommendation for treatment can currently be made, although some centers consider treating HMPV LRTID with ribavirin and/or IVIG despite the lack of supporting studies 1. It is essential to prioritize supportive care, focusing on managing symptoms, as there are no specific antiviral medications approved for HMPV. Prevention measures, such as regular handwashing, avoiding close contact with sick individuals, and covering coughs and sneezes, are crucial in reducing the transmission of HMPV.
From the Research
Definition and Overview of Human Metapneumovirus
- Human Metapneumovirus (hMPV) is a respiratory virus that was first identified in 2001 2, 3.
- It is a major cause of upper and lower respiratory tract infections, particularly in young children, the elderly, and immunocompromised individuals 2, 3, 4, 5.
- hMPV is responsible for approximately 5% to 10% of hospitalizations due to acute respiratory tract infections in children 2.
Transmission and Clinical Manifestations
- The virus is transmitted through droplets, direct contact, and surface contamination, with crowded spaces and healthcare facilities serving as key environmental amplifiers 3.
- Clinical manifestations of hMPV infection range from mild cold-like symptoms to severe pneumonia, often overlapping with those of other respiratory pathogens like RSV and COVID-19 2, 3, 4.
- Severe disease occurs most commonly in infants, the elderly, chronically ill, and immunocompromised hosts 4, 5.
Diagnosis and Treatment
- Molecular methods, such as reverse transcriptase PCR (RT-PCR), are the preferred diagnostic modality for detecting hMPV due to the slow growth of the virus in cell culture 2.
- Treatment options are limited, but oral ribavirin and intravenous immunoglobulin have shown promise in severe cases, particularly in immunocompromised patients 4, 6.
- There are currently no approved vaccines or targeted antiviral therapies available, highlighting the need for intensified research into preventive measures and therapeutic strategies 2, 3.
Immune Evasion Mechanisms
- hMPV induces a poor innate immune response, affecting adaptive immunity, and promotes an anergic state in T cells 5.
- The virus interferes with pattern recognition receptors (PRRs) and cell signaling pathways triggered by interferon-associated genes, although the exact mechanisms are still unclear 5.
- Viral glycoproteins, such as G and SH, may play immune-modulator roles during infection, contributing to the virus's ability to evade the host immune system 5.