Genetic Diversity of Human Metapneumovirus over 4 Consecutive Years in Australia

The molecular epidemiologic profile of human metapneumovirus (hMPV) infection has likely been skewed toward certain genetic subtypes because of assay-design issues, and no comprehensive studies have been conducted to date. Here, reverse-transcription polymerase chain reaction was used to screen 10,319 specimens from patients presenting to hospitals with suspected respiratory tract infections during 2001–2004. After analysis of 727 Australian hMPV strains, 640 were assigned to 1 of 4 previously described subtypes. hMPV was the most common pathogen detected, and subtype B1 was the most common lineage. Concurrent, annual circulation of all 4 hMPV subtypes in our study population was common, with a single, usually different hMPV subtype predominating in each year