Human metapneumovirus in lung transplant recipients and comparison to respiratory syncytial virus.

RATIONALE: Human metapneumovirus is a newly described virus isolated in 2001 from children with acute respiratory viral infection. It has subsequently been reported globally, although there are limited data in lung transplant recipients. OBJECTIVES: To prospectively analyze whether human metapneumovirus was circulating in our adult lung transplant community and assess the morbidity of this infection and to compare the clinical presentation and outcome after intravenous ribavirin of human metapneumovirus with that of respiratory syncytial virus (RSV). METHODS: Lung transplant patients with clinical features of respiratory viral infection underwent nasopharyngeal aspirates. Patients with a positive specimen for RSV or human metapneumovirus by reverse transcriptase-polymerase chain reaction analysis and graft dysfunction received intravenous ribavirin and pulse steroid therapy. MEASUREMENTS AND MAIN RESULTS: Eighty-nine patients had 199 visits for aspirate studies. A viral cause was determined for 62 visits in 47 patients (19 human metapneumovirus, 18 RSV, 13 parainfluenza, 9 influenza A, 2 adenovirus, and 1 influenza B). A significant percentage of patients with metapneumovirus (63%) and RSV (72%) developed graft dysfunction, with average declines in FEV(1) of 30 +/- 12.4% and 25.9 +/- 11.2%, respectively. In these patients, bronchiolitis obliterans syndrome onset or progression occurred in no patients with human metapneumovirus compared with 5 of 13 (38%) patients with RSV at 6 months. CONCLUSIONS: Human metapneumovirus is a leading cause of acute respiratory tract illness in lung transplant recipients. The incidence and clinical spectrum at presentation are similar to RSV, although the latter seems to be associated with a higher risk of chronic rejection. We recommend testing of nasopharyngeal aspirates for human metapneumovirus with polymerase chain reaction to assess local epidemiologic patterns.

Human metapneumovirus, Australia, 2001-2004.

We examined 10,025 respiratory samples collected for 4 years (2001-2004) and found a 7.1% average annual incidence of human metapneumovirus. The epidemic peak of infection was late winter to spring, and genotyping showed a change in predominant viral genotype in 3 of the 4 years.

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.