Control of an outbreak due to an adamantane-resistant strain of influenza A (H3N2) in a chronic care facility.
BACKGROUND
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.


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


RESULTS
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.


CONCLUSIONS
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.
Cohen
N J
NJ
Chicago Department of Public Health, Chicago, IL, USA. NCohen@cdc.gov
Morita
J Y
JY
Plate
D K
DK
Jones
R C
RC
Simon
M T
MT
Nawrocki
J
J
Siston
A M
AM
Gerber
S I
SI
D000218:Adamantane / Q000627:therapeutic use*; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D024882:Drug Resistance, Viral; D005260:Female; D006801:Humans; D017053:Infection Control; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D009154:Mutation; D009735:Nursing Homes; D012189:Retrospective Studies; D055815:Young Adult
D000218:Adamantane