956Management of a respiratory outbreak due to concomitantly circulating influenza A and parainfluenza 1 in a residential care facility

Introduction: Respiratory viruses are common causes of outbreaks in residential care. Multiplex PCR assays for respiratory viruses enable the detection of multiple viruses, though the clinical significance of dual infections is unclear. We describe an outbreak of 2 respiratory viruses cocirculating in a residential care facility in Vancouver, Canada. Methods: Outbreak investigation was conducted in a facility with 216 residents distributed among 3 separate units in January 2014. Cases were defined as any resident or staff with acute onset respiratory illness [fever (>38.0°C) and cough], and with at least one of the following: sore throat, nasal congestion, malaise, chills, muscle aches, headache or change in mental status. Affected patients were placed on contact and droplet precautions. Nasopharyngeal swabs were collected on symptomatic residents and tested using an in-house multiplex PCR assay (influenza A/B, respiratory syncytial virus, parainfluenza 1/2/3, adenovirus and human metapneumovirus). An epidemic curve of the outbreak was created. Results: The outbreak persisted for 13 days. Twelve patients were infected, including 7 with parainfluenza 1, 2 with influenza A and 3 with parainfluenza 1/influenza A co-infection (Figure 1). All patients manifesting respiratory symptoms were tested (12/28, 43%), rather than empirically treating subsequent patients meeting case definition. Treatment with oseltamivir was provided for 5 patients positive for influenza A, with all others receiving prophylaxis. Two staff developed upper respiratory tract symptoms and were considered cases. Outbreak management also included cessation of group activities, closure to admissions and enhanced unit cleaning. Influenza vaccination rates were 94% for residents and 83% for healthcare workers. Conclusion: Routine testing using a multiplex PCR assay detected a respiratory outbreak involving single and co-infections. Two circulating viruses can affect outbreak management. In this outbreak, all symptomatic residents were tested and confirmed rather than empirically treated. In addition to accurate classification and management of cases, overall consumption of oseltamivir prophylaxis can be reduced by monitoring for the persistence of both viruses.