High prevalence of human metapneumovirus subtype B in cases presenting as severe acute respiratory illness: an experience at tertiary care hospital

Abstract

Purpose: A comparatively newly discovered human metapneumovirus (HMPV) has emerged as an important cause of severe acute respiratory illness (SARI), second only to respiratory syncytial virus (RSV). RSV and HMPV taxonomically belong to same family and subfamily, and their clinical presentation and seasonal distribution are also seemed to be indistinguishable. Present study was planned to know the epidemiology and prevalence of HMPV and RSV in patients presented as SARI in a tertiary care hospital.

Methods: Nasopharyngeal aspirate of 440 patients fulfilling World Health Organization criteria of SARI, enrolled during a 2-year study period, were collected and tested for the presence of RSV, HMPV and their subtypes A and B by real time polymerase chain reaction along with other respiratory viruses, viz influenza A, B, parainfluenza 1, 2, 3, 4, adenovirus, measles virus and bocavirus. The demographic details, clinical profile, underlying diseases, clinical diagnosis at the time of admission and seasonal distribution were studied and analyzed statistically.

Results: Overall positivity of RSV was 14.3% (24.68% in <5 years) and of HMPV was 3.63% (5.1% in <5 years and 5.08% in 6-12 years). Among RSV, subtype A (89%), and among HMPV, genotype B (68.8%) were predominating. Adults having underlying chronic obstructive pulmonary disease were more prone to acquire RSV and HMPV infections. RSV and HMPV positivity was restricted to winter season. We are reporting replacement of RSV with HMPV in this population.

Conclusions: HMPV has emerged as an important cause of SARI in children <12 years of age. Alternative predominance of RSV and HMPV is an important observation.

Keywords: epidemiology; human metapneumovirus; nasopharyngeal aspirate; respiratory syncytial virus; severe acute respiratory illness.