Co-circulation of multiple genotypes of human rhinovirus during a large outbreak of respiratory illness in a veterans’ long-term care home

Mubareka, Samira; Louie, Lisa; Wong, Henry; Granados, Andrea; Chong, Sylvia; Luinstra, Kathy; Petrich, Astrid; Smieja, Marek; Vearncombe, Mary; Mahony, James; Simor, Andrew

BACKGROUND: Human rhinoviruses (HRVs) are a well-recognized cause of long-term care home (LTCH) outbreaks of respiratory illness. However, there are limited data on the molecular epidemiology of the HRV types involved. OBJECTIVES: To determine whether a large respiratory outbreak in a LTCH was caused by a single type of HRV, and to describe the clinical impact of the outbreak. STUDY DESIGN: Nasopharyngeal swabs were collected from residents with one or more of the following: fever, cough, rhinitis, or congestion. Specimens were interrogated by multiplex PCR using the ResPlex II assay. Samples positive for HRV were then submitted for genotyping by partial sequence analysis of the 5′ untranslated (UTR) and viral protein (VP) 1 capsid regions. RESULTS: Of 71 screened, 56 residents were positive for a HRV during an outbreak that lasted 5.5 weeks; 27 healthcare workers also had respiratory symptoms. Three residents were transferred to hospital and 2 died. Seven units in two wings of the LTCH were affected, resulting in 3152.5 resident unit closure days. Three different HRV genotypes were identified, although HRV-A1 dominated. CONCLUSIONS: This large outbreak of HRVs among residents and healthcare workers in a LTCH was associated with substantial resident and staff morbidity as well as significant unit closures. Multiple types of HRV were implicated but an HRV-A1 type dominated, warranting further investigation into viral determinants for virulence and transmission.