Prevalence of Human Metapneumovirus Infection in Hospital Wards Handling Patients with Severe Motor and Intellectual Disabilities

Abstract

Epidemics of infectious diseases often occur in hospital wards handling patients with severe motor and intellectual disabilities. However, the causative pathogens are not identified in half of these epidemics. Recently, an epidemic occurred in 2 wards consecutively in the National Hospital Organization Ehime Hospital in March-April, 2010. In this epidemic, 18 of 40 patients in one ward and 14 of 60 patients in another ward showed symptoms, and human metapneumovirus (HMPV) was detected from pharyngeal and/or nasal swabs of 4 patients. Phylogenetic analysis of the viral genomes showed that the virus belonged to subgroup B2, and the same virus had spread consecutively in 2 wards. High fever lasted for 5.3 days on average in the 32 inpatients, was mostly over 38 degrees C and was accompanied by productive coughs. In the 4 patients in whom human HMPV was detected, the number of peripheral blood lymphocytes decreased but that of monocytes increased. Pneumonia developed in two patients as shown by chest radiography, and an increased number of peripheral blood neutrocytes and increased CRP levels were noted. Of the 151 inpatients, anti-human HMPV antibody was found in the sera of 143 (95%), and the relationship between high fever and antibody titer was not significant, indicating that HMPV infection could recur in spite of the presence of specific antibodies. Because human HMPV is highly prevalent, and causes high fever and pneumonia, hospital staff should be vigilant for any signs of this virus in hospital wards and take steps to prevent infection in long-term inpatients.