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Seroepidemiologic investigation of an outbreak of pandemic influenza A H1N1 2009 aboard a US Navy vessel--San Diego, 2009.
Influenza Other Respir Viruses. 2013 Sep; 7(5):791-8.IO

Abstract

BACKGROUND

During summer 2009, a US Navy ship experienced an influenza-like illness outbreak with 126 laboratory-confirmed cases of pandemic influenza A (H1N1) 2009 virus among the approximately 2000-person crew.

METHODS

During September 24-October 9, 2009, a retrospective seroepidemiologic investigation was conducted to characterize the outbreak. We administered questionnaires, reviewed medical records, and collected post-outbreak sera from systematically sampled crewmembers. We used real-time reverse transcription-PCR or microneutralization assays to detect evidence of H1N1 virus infection.

RESULTS

Retrospective serologic data demonstrated that the overall H1N1 virus infection attack rate was 32%. Weighted H1N1 virus attack rates were higher among marines (37%), junior-ranking personnel (34%), and persons aged 19-24 years (36%). In multivariable analysis, a higher risk of illness was found for women versus men (odds ratio [OR] = 2.2; 95% confidence interval [CI]: 1.1-4.4), marines versus navy personnel (OR = 1.7; 95% CI, 1.0-2.9), and those aged 19-24 versus ≥ 35 years (OR = 3.9; 95% CI, 1.2-12.8). Fifty-three percent of infected persons did not recall respiratory illness symptoms. Among infected persons, only 35% met criteria for acute respiratory illness and 11% for influenza-like illness.

CONCLUSIONS

Approximately half of H1N1 infections were asymptomatic, and thus, the attack rate was higher than estimated by clinical illness alone. Enhanced infection control measures including pre-embarkation illness screening, improved self-reporting of illness, isolation of ill and quarantine of exposed contacts, and prompt antiviral chemoprophylaxis and treatment might be useful in controlling shipboard influenza outbreaks.

Authors+Show Affiliations

Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA, USA. igc9@cdc.govNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

23496798

Citation

Khaokham, Christina B., et al. "Seroepidemiologic Investigation of an Outbreak of Pandemic Influenza a H1N1 2009 Aboard a US Navy vessel--San Diego, 2009." Influenza and Other Respiratory Viruses, vol. 7, no. 5, 2013, pp. 791-8.
Khaokham CB, Selent M, Loustalot FV, et al. Seroepidemiologic investigation of an outbreak of pandemic influenza A H1N1 2009 aboard a US Navy vessel--San Diego, 2009. Influenza Other Respir Viruses. 2013;7(5):791-8.
Khaokham, C. B., Selent, M., Loustalot, F. V., Zarecki, S. M., Harrington, D., Hoke, E., Faix, D. J., Ortiguerra, R., Alvarez, B., Almond, N., McMullen, K., Cadwell, B., Uyeki, T. M., Blair, P. J., & Waterman, S. H. (2013). Seroepidemiologic investigation of an outbreak of pandemic influenza A H1N1 2009 aboard a US Navy vessel--San Diego, 2009. Influenza and Other Respiratory Viruses, 7(5), 791-8. https://doi.org/10.1111/irv.12100
Khaokham CB, et al. Seroepidemiologic Investigation of an Outbreak of Pandemic Influenza a H1N1 2009 Aboard a US Navy vessel--San Diego, 2009. Influenza Other Respir Viruses. 2013;7(5):791-8. PubMed PMID: 23496798.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Seroepidemiologic investigation of an outbreak of pandemic influenza A H1N1 2009 aboard a US Navy vessel--San Diego, 2009. AU - Khaokham,Christina B, AU - Selent,Monica, AU - Loustalot,Fleetwood V, AU - Zarecki,Shauna Mettee, AU - Harrington,Douglas, AU - Hoke,Eileen, AU - Faix,Dennis J, AU - Ortiguerra,Ryan, AU - Alvarez,Bryan, AU - Almond,Nathaniel, AU - McMullen,Kellie, AU - Cadwell,Betsy, AU - Uyeki,Timothy M, AU - Blair,Patrick J, AU - Waterman,Stephen H, Y1 - 2013/03/17/ PY - 2013/01/03/accepted PY - 2013/3/19/entrez PY - 2013/3/19/pubmed PY - 2014/3/13/medline KW - Disease outbreaks KW - H1N1 subtype KW - epidemiology KW - influenza A virus KW - military personnel SP - 791 EP - 8 JF - Influenza and other respiratory viruses JO - Influenza Other Respir Viruses VL - 7 IS - 5 N2 - BACKGROUND: During summer 2009, a US Navy ship experienced an influenza-like illness outbreak with 126 laboratory-confirmed cases of pandemic influenza A (H1N1) 2009 virus among the approximately 2000-person crew. METHODS: During September 24-October 9, 2009, a retrospective seroepidemiologic investigation was conducted to characterize the outbreak. We administered questionnaires, reviewed medical records, and collected post-outbreak sera from systematically sampled crewmembers. We used real-time reverse transcription-PCR or microneutralization assays to detect evidence of H1N1 virus infection. RESULTS: Retrospective serologic data demonstrated that the overall H1N1 virus infection attack rate was 32%. Weighted H1N1 virus attack rates were higher among marines (37%), junior-ranking personnel (34%), and persons aged 19-24 years (36%). In multivariable analysis, a higher risk of illness was found for women versus men (odds ratio [OR] = 2.2; 95% confidence interval [CI]: 1.1-4.4), marines versus navy personnel (OR = 1.7; 95% CI, 1.0-2.9), and those aged 19-24 versus ≥ 35 years (OR = 3.9; 95% CI, 1.2-12.8). Fifty-three percent of infected persons did not recall respiratory illness symptoms. Among infected persons, only 35% met criteria for acute respiratory illness and 11% for influenza-like illness. CONCLUSIONS: Approximately half of H1N1 infections were asymptomatic, and thus, the attack rate was higher than estimated by clinical illness alone. Enhanced infection control measures including pre-embarkation illness screening, improved self-reporting of illness, isolation of ill and quarantine of exposed contacts, and prompt antiviral chemoprophylaxis and treatment might be useful in controlling shipboard influenza outbreaks. SN - 1750-2659 UR - https://www.unboundmedicine.com/medline/citation/23496798/Seroepidemiologic_investigation_of_an_outbreak_of_pandemic_influenza_A_H1N1_2009_aboard_a_US_Navy_vessel__San_Diego_2009_ L2 - https://doi.org/10.1111/irv.12100 DB - PRIME DP - Unbound Medicine ER -