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Control of an Outbreak due to an Adamantane-Resistant Strain of Influenza A (H3N2) in a Chronic Care Facility



Chronic care facility residents are at risk of severe influenza infection and death. Adamantanes have been used by chronic care facilities for influenza A prophylaxis; however, genotypic resistance has altered prophylaxis recommendations. An outbreak of influenza A (H3N2) in a chronic care facility housing neurologically impaired children and young adults and subsequent control measures are described.

Patients and Methods:

Resident charts were retrospectively reviewed. Isolates were characterized by strain identification and pyrosequencing.


Although 95 (97%) of 98 residents had been immunized against influenza at the start of the influenza season, 16 (84%) of 19 case patients were identified on the first floor. However, following implementation of enhanced infection control practices and adamantane prophylaxis, only 10 (13%) of 79 case patients were identified on the second floor. Subsequent pyrosequencing studies revealed a serine to asparagine mutation at position 31 of the M2 protein.


Enhanced infection control precautions and adamantane prophylaxis were used to control spread of influenza in a chronic care facility. This outbreak demonstrates the importance of timely and consistent implementation of infection control measures in controlling influenza outbreaks in long term care facilities and raises questions about a possible role for adamantanes in preventing transmission of adamantane-resistant influenza A viruses.

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Correspondence to N. J. Cohen.

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Cohen, N.J., Morita, J.Y., Plate, D.K. et al. Control of an Outbreak due to an Adamantane-Resistant Strain of Influenza A (H3N2) in a Chronic Care Facility. Infection 36, 458–462 (2008).

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  • Amantadine
  • Adamantanes
  • Zanamivir
  • Infection Control Measure
  • Rimantadine