Human metapneumovirus in hospitalized children -: A review

The human Metapneumovirus (HMPV) has been discovered by von den Hoogen et al. in 2001 and seems to play an important role as etiologic agent in childhood respiratory tract infections in particular involving infants after the 6th month of life and toddlers. Duly considering the hitherto published studies and retrospective analysis of two HMPV seasons (2002-2004) at our institution this review focuses on children, who had to be hospitalized due to HMPV infection. The analysis confirmed, that among those patients there is a high proportion of children with pre-existing risk factors for a complicated clinical course, a high proportion of children with bronchiolitis or pneumonia and a relevant proportion of children with HMPV related apnoeas, most prevalent in the prematurely born. Although the first HMPV infection takes place somewhat later in infancy, the data do not show that HMPV infection is in general milder than RSV infection in hospitalized children. Clinical symptoms and radiological signs do not permit tentative conclusions on the causative agent. This underlines the necessity of specific diagnostic efforts (in case of HMPV with PCR). HMPV may cause lobar or segmental pneumonias difficult to distinguish from bacterial lower respiratory tract infection. Children admitted to the hospital with an acute exacerbation of asthma bronchiale or cystic fibrosis should not only be tested for RSV but also for HMPV. Prospective studies investigating specific therapeutic interventions or describing the impact and prevention of nosocomial HMPV in fection are awaited for. There has been one report of a meningoencephalitis possibly related to HMPV. Thus, liquor samples in such cases should be tested for HMPV too.