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Case Reports
. 2012 Sep;6(5):374-9.
doi: 10.1111/j.1750-2659.2011.00322.x. Epub 2012 Jan 2.

An outbreak of the 2009 influenza a (H1N1) virus in a children's hospital

Allison Bearden  1 , Thomas C Friedrich, Tony L Goldberg, Barbara Byrne, Carol Spiegel, Peter Schult, Nasia Safdar
Affiliations
Case Reports

An outbreak of the 2009 influenza a (H1N1) virus in a children's hospital

Allison Bearden et al. Influenza Other Respir Viruses. 2012 Sep.

Abstract

Context: Preventing nosocomial transmission of influenza is essential to reduce the morbidity and mortality associated with this infection. In October 2009, an outbreak of the 2009 influenza A (H1N1) virus occurred in a hematology ward of a children's hospital over a 21-day period and involved two patients and four healthcare workers.

Objective: To investigate nosocomial transmission of the 2009 influenza A (H1N1) virus in patients and healthcare workers.

Design, setting, and participants: An outbreak investigation was initiated in response to suspected nosocomial transmission of the 2009 influenza A (H1N1) virus during the peak of the 2009 pandemic. Cases were confirmed using a polymerase chain reaction (PCR) test specific for the 2009 H1N1 influenza A virus. Viruses isolated from nasopharyngeal swabs were genetically characterized using Sanger sequencing of uncloned "bulk" PCR products.

Main outcome measures: Virus sequencing to investigate nosocomial transmission.

Results: Two immunocompromised patients and four healthcare workers were found to be part of a nosocomial outbreak of the 2009 influenza A (H1N1) virus. One immunocompromised patient had a second episode of clinical influenza infection after isolation precautions had been discontinued, resulting in additional exposures. Strain-specific PCR showed that all cases were caused by infection of the 2009 H1N1 virus. Sequencing of viral genes encoding hemagglutinin and polymerase basic subunit 2 (PB2) revealed that all viruses isolated were genetically identical at these loci, including the two episodes occurring in the same immunocompromised patient.

Conclusions: Prompt institution of isolation precautions is essential in preventing nosocomial outbreaks of the 2009 novel influenza A (H1N1) virus. Our data suggest that isolation precautions may need to be continued for a prolonged period of time in immunocompromised patients with influenza infection.

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Figures

Figure 1
Figure 1
Epidemiologic curve. X‐axis: day of outbreak, Y‐axis: number of individuals infected per day. HCW, Healthcare worker.
See this image and copyright information in PMC

References

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