Human metapneumovirus epidemiological and evolutionary patterns in Coastal Kenya, 2007-11

Betty E Owor,Charles N Agoti,Regina W Njeru,D James Nokes,Lilian C Mwango,Geoffrey N Masankwa

doi:10.1186/s12879-016-1605-0

Abstract

BackgroundHuman metapneumovirus (HMPV) is an important global cause of severe acute respiratory infections in young children and the elderly. The epidemiology of HMPV in sub-Saharan Africa is poorly described and factors that allow its recurrent epidemics in communities not understood.MethodsWe undertook paediatric inpatient surveillance for HMPV in Kilifi County Hospital (KCH) of Coastal Kenya between 2007 and 2011. Nasopharyngeal samples collected from children aged 1 day–59 months admitted with severe or very severe pneumonia, were tested for HMPV using real-time polymerase chain reaction (RT-PCR). Partial nucleotide sequences of the attachment (G) and fusion (F) surface proteins of positive samples were determined and phylogenetically analyzed.ResultsHMPV was detected in 4.8 % (160/3320) of children [73.8 % (118/160) of these less than one year of age], ranging between 2.9 and 8.8 % each year over the 5 years of study. HMPV infections were seasonal in occurrence, with cases predominant in the months of November through April. These months frequently coincided with low rainfall, high temperature and low relative humidity in the location. Phylogenetic analysis of partial F and G sequences revealed three subgroups of HMPV, A2 (74 %, 91/123), B1 (3.2 %, 4/123) and B2 (22.8 %, 28/123) in circulation, with subgroup A2 predominant in majority of the epidemic seasons. Comparison of G sequences (local and global) provided a greater phylogenetic resolution over comparison of F sequences and indicated presence of probable multiple G antigenic variants within the subgroups due to differences in amino acid sequence, encoded protein length and glycosylation patterns.ConclusionThe present study reveals HMPV is an important seasonal contributor to respiratory disease hospitalization in coastal Kenya, with an evolutionary pattern closely relating to that of respiratory syncytial virus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1605-0) contains supplementary material, which is available to authorized users.

Highlights

Human metapneumovirus (HMPV) is an important global cause of severe acute respiratory infections in young children and the elderly
Study population Between January 2007 and December 2011, there were 16,439 admissions to Kilifi County Hospital (KCH) aged between 1 day and 59 months, of which 32.1 % (5284) were eligible for study as cases with syndromic severe or very severe pneumonia (Table 1)
The HMPV infections in KCH admissions were most common in children

Summary

Introduction

Human metapneumovirus (HMPV) is an important global cause of severe acute respiratory infections in young children and the elderly. Human metapneumovirus (HMPV), a close relative of respiratory syncytial virus (RSV), is a recognized major human pathogen that causes epidemics of respiratory tract illnesses in persons of all ages worldwide [1, 2]. A member of the Paramyxoviridae family of viruses, HMPV genome is a negative-sense single-stranded RNA molecule, 13.3 Kb long, encoding eight proteins [5]. Three surface proteins F (fusion), G (attachment glycoprotein) and SH (small hydrophobic) are encoded within the HMPV genome [6] and F and G nucleotide sequences have been largely used to study HMPV genetic variation [7].

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Conclusion