Exposure to patients with influenza persists despite hospital surveillance.

According to study results published in Infection Control and Hospital Epidemiology, a large community hospital in Toronto failed to diagnose one in six patients with influenza until they had exposed other patients and health care workers for more than 24 hours. Strategies to reduce transmission of influenza in hospitals include vaccination, the exclusion of ill staff and visitors, adherence to good hand hygiene routines, screening to detect influenza illness in patients, additional precautions used to care for patients with influenza, and antiviral agent despite implementation of such strategies, health care-acquired influenza and influenza outbreaks continue to occur. The researchers assessed the frequency, risk factors, transmission and exposure associated with influenza in hospitalized patients at North York General Hospital, a 426-bed community teaching hospital with active surveillance, in Toronto, Canada. They collected prospective data from consenting patients with laboratory-confirmed influenza admitted from Oct. 1 to April 30 during the 2012-2013, 2013-2014 and 2014-2015 influenza seasons. Upon admission, only 557 of 661 patients with influenza were placed on additional precautions. The investigators observed that out of 104 patients presenting with influenza symptoms after admission, 47 were nosocomial cases and 57 were community-onset cases. After reviewing medical charts, they found that 78 cases detected after admission exposed 143 roommates. Among those tested for influenza after exposure, no roommates of community-onset cases, and two of 16 roommates of nosocomial cases, were diagnosed with influenza, the researchers reported. The researchers said that out of 637 influenza-positive patients, 25% and 57% met the definitions of influenza-like illness established by the Public Health Agency of Canada (PHAC) and the CDC, respectively, and 70.3% met the Provincial Infectious Diseases Advisory Committee (PIDAC) definition of febrile respiratory illness. Only 13%, 23% and 34% of the 56 patients with community-onset influenza discovered after admission met the PHAC, CDC and PIDAC classifications, respectively. Exposure to patients with influenza persisted in the hospital despite an intensive program to reduce the exposure of health care workers and other patients,because exposure to patients can occur prior to symptom onset. Patients with atypical symptoms, emphasis should be on optimal hand hygiene and vaccination of health care workers is a necessary adjunct to routine and additional precautions if patients and workers are to be best protected against influenza.