Characteristics of Human Metapneumovirus Infection Prevailing in Hospital Wards Housing Patients with Severe Disabilities

Abstract

SUMMARY: Epidemics of infectious diseases often occur at long-term inpatient facilities for patients with severe motor and intellectual disabilities. However, the pathogens causing these infections remain unknown in approximately half of such epidemics. Two epidemics of respiratory tract infection occurred in 2 wards in the National Hospital Organization Ehime Hospital (prevalence 1, 34 infected out of 59 inpatients in the A ward in September 2011; prevalence 2, 8 infected out of 58 inpatients in the B ward in June 2012). Human metapneumovirus (HMPV) was detected from the nasal (and some pharyngeal) swabs from 17 patients. Based on phylogenetic analysis of viral genomes, the virus was grouped in subgroup A2 (prevalence 1) and B2 (prevalence 2). We considered that the viruses had spread through the 2 wards. The average duration of high fever in the 42 patients was 6.8 days, with the majority of fevers exceeding 389 C (79z) and being accompanied by a productive cough. Ten out of 17 patients (59z) in whom HMPV was detected had decreased lymphocyte and increased monocyte counts in the blood. Eleven cases (65z) had elevated-C reactive protein levels and fever protraction as well as images of bronchitis or pneumonia on chest radiographs approximately 1 week after onset. Anti-HMPV antibody in the blood was positive in 95z of patients (151 of 159 inpatients), indicating no relation between HMPV infection and antibody titer but revealing recurrent infections. In view of the fever protraction and frequent co-occurrence of bronchitis and pneumonia at long-term inpatient facilities for immunocompromised patients such as the ones in this study, the prevalence of HMPV must be carefully monitored, and preventive measures and early-stage treatments are required.

Alteration in Serum Levels of Inflammatory Cytokines during Parainfluenza Virus Type 1 Infection in Patients with Severe Multiple Disabilities

“…The present study results are similar to those of reported outbreaks of metapneumovirus infection (12).…”

Human metapneumovirus: review of an important respiratory pathogen

“…53 However, the most common causes of hospitalization are bronchiolitis and pneumonia. 54 The average duration of fever in hMPV-positive cases is about 10 days, with a peak during the course of the illness. 55 Young adults with hMPV re-infection show mild cold and flu-like symptoms, with fever in a small proportion of infected cases.…”

Modulation of Host Immunity by the Human Metapneumovirus

“…HMPV can produce asymmetric, acute interstitial pneumonia and bronchitis in immunocompromised adults, as evidenced by parenchymal airspace consolidations and bronchial wall thickening in chest computed tomography (CT) scans (32). Fever of Ͼ38°C, lymphopenia with monocytosis, increased C-reactive protein levels, and chest radiographs indicative of bronchitis and pneumonia have been also described for adults infected with HMPV (33). In healthy adults, experimental infection with HMPV produces symptoms including headaches, nasal congestion, pharyngitis, cough, hoarseness, cervical lymphadenopathy, and recurrence of herpes labialis (34).…”