Abstract
BACKGROUND: Data on human metapneumovirus (HMPV)-associated severe acute respiratory illness (SARI) are limited in settings with high human immunodeficiency virus (HIV) infection prevalence. OBJECTIVES: To describe clinical characteristics and seasonality (all sites), and incidence (Soweto only) of HMPV-associated SARI among children and adults. STUDY DESIGN: Active, prospective, hospital-based, sentinel surveillance for patients hospitalised with SARI was conducted at four sites in South Africa from February 2009-December 2013. Upper respiratory tract samples were tested by multiplex real-time polymerase chain reaction assays for HMPV and other respiratory viruses. Incidence of hospitalisation, stratified by age and HIV-infection status, was calculated for one hospital with population denominators. RESULTS: HMPV was identified in 4.1% of patients enrolled, including 5.6% (593/10503) in children and 1.7% in adults (≥18 years; 119/6934). The majority of adults (84.0%) had an underlying medical condition, including HIV infection in 87/110 (79.1%). HMPV detection occurred perennially with periods of increased detection, which varied from year to year. The incidence of HMPV-associated hospitalisation in Soweto was highest in infants (653.3 per 100,000 person years; 95% confidence interval (CI) 602.2-707.6). The incidence was higher in HIV-infected persons compared to HIV-uninfected persons in age-groups 5-17 years (RR 6.0; 1.1-20.4), 18-44 years (RR 67.6; 38.0-132.6) and 45-64 years (RR 5.3; 3.4-8.3), while not differing in other age-groups. CONCLUSIONS: The burden of HMPV-associated SARI hospitalisation among adults occurred predominantly in HIV-infected persons. Among children, infants were at highest risk, with similar burden of hospitalisation in HIV-infected and HIV-uninfected children.