Pulmonary Complications of Interpandemic Influenza A in Hospitalized Adults

Division of General Medicine, University of Rochester, Rochester, New York, United States
The Journal of Infectious Diseases (Impact Factor: 6). 04/2007; 195(7):1029-37. DOI: 10.1086/512160
Source: PubMed


To define the pulmonary complications of influenza during the current interpandemic period, we reviewed clinical, laboratory, and radiographic data from 193 adults (> or =18 years old) (1999-2003) who were hospitalized with influenza A during 4 winters.
The mean age was 75 years, 8% had documented bacterial infection, 15% required intensive care unit treatment, and 6% died. Chest radiograph (CXR) findings were classified as showing acute disease (AD; n=101) or no AD (NAD; n=92). Most CXR findings were subtle in nature. Subjects with AD were more likely to have > or =1 cardiac diagnosis (odds ratio [OR], 2.2 [95% confidence interval {CI}, 1.2-4.1]), to have rales on examination (OR, 1.9 [95% CI, 1.0-3.7]), to be symptomatic for >3 days (OR, 2.2 [95% CI, 1.2-4.1]), and to be less likely to wheeze (OR, 0.37 [95% CI, 0.20-0.70]). Total and neutralizing anti-influenza antibody titers were lower in patients with influenza than in respiratory syncytial virus-infected control subjects (P<.05), which suggests a protective effect of antibody. Interestingly, antibody titers did not differ between subjects with AD and those with NAD.
In the absence of significant antigenic shifts, previous exposure to influenza, including vaccinations, may play a role in reducing the severity of influenza-associated lower respiratory tract disease.

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    • "Hospitalized influenzainfected individuals demonstrate lower total and neutralizing anti-influenza antibody titers than do respiratory syncytial virusinfected control subjects. This difference suggests a protective effect of higher influenza antibody titers [7]. An overall reduction in antibody titers produced during severe acute influenza infection occurs in both human and mouse models [8] [9] [10]. "
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    ABSTRACT: Background: Early antibody responses to influenza infection are important in both clearance of virus and fighting the disease. Acute influenza antibody titers directed toward H1-antigens and their relation to infection type and patient outcomes have not been well investigated. Objective: Using hemagglutination inhibition (HI) assays, we aimed to characterize the H1-specific antibody titers in patients with influenza infection or another respiratory infection before and after the H1N1-pandemic influenza outbreak. Among patients with acute influenza infection we related duration of illness, severity of symptoms, and need for hospitalization to antibody titers. Methods: There were 134 adult patients (average age 34.7) who presented to an urban academic emergency department (ED) from October through March during the 2008-2011 influenza seasons with symptoms of fever and a cough. Nasal aspirates were tested by viral culture, and peripheral blood serum was run in seven H1-subtype HI assays. Results: Acutely infected influenza patients had markedly lower antibody titers for six of the seven pseudotype viruses. For the average over the seven titers (log units, base 2) their mean was 7.24 (95% CI 6.88, 7.61) compared with 8.60(95% CI 8.27, 8.92) among patients who had a non-influenza respiratory illness, p < 0.0001. Among patients with seasonal influenza infection, titers of some antibodies correlated with severity of symptoms and with total duration of illness (p < 0.02). Conclusion: In patients with acute respiratory infections, lower concentrations of H1-influenza-specific antibodies were associated with influenza infection. Among influenza-infected patients, higher antibody titers were present in patients with a longer duration of illness and with higher severity-of-symptom scores.
    Full-text · Article · May 2014 · Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology
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    • "A study from Denmark examining all influenza-associated hospital admissions also did not find an increase during the first epidemic of influenza A(H1N1)pdm09 virus compared with seasonal influenza, except in people younger than 65 years [26]. Our findings are consistent with those of a study in a US hospital that found that patients at greatest risk of complications from seasonal influenza tend to be older, with a mean age of 75 years [27]. The 2010 epidemic, the first season following the arrival of pandemic influenza continued to be dominated by the pandemic strain. "
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    ABSTRACT: Background In Australia, the 2009 epidemic of influenza A(H1N1)pdm09 resulted in increased admissions to intensive care. The annual contribution of influenza to use of intensive care is difficult to estimate, as many people with influenza present without a classic influenza syndrome and laboratory testing may not be performed. We used a population-based approach to estimate and compare the impact of recent epidemics of seasonal and pandemic influenza. Methods For 2007 to 2010, time series describing health outcomes in various population groups were prepared from a database of all intensive care unit (ICU) admissions in the state of New South Wales, Australia. The Serfling approach, a time series method, was used to estimate seasonal patterns in health outcomes in the absence of influenza epidemics. The contribution of influenza was estimated by subtracting expected seasonal use from observed use during each epidemic period. Results The estimated excess rate of influenza-associated respiratory ICU admissions per 100,000 inhabitants was more than three times higher in 2007 (2.6/100,000, 95% CI 2.0 to 3.1) than the pandemic year, 2009 (0.76/100,000, 95% CI 0.04 to 1.48). In 2009, the highest excess respiratory ICU admission rate was in 17 to 64 year olds (2.9/100,000, 95% CI 2.2 to 3.6), while in 2007, the highest excess rate was in those aged 65 years or older (9.5/100,000, 95% CI 6.2 to 12.8). In 2009, the excess rate was 17/100,000 (95% CI 14 to 20) in Aboriginal people and 14/100,000 (95% CI 13 to 16) in pregnant women. Conclusion While influenza was diagnosed more frequently and peak use of intensive care was higher during the epidemic of pandemic influenza in 2009, overall excess admissions to intensive care for respiratory illness was much greater during the influenza season in 2007. Thus, the impact of seasonal influenza on intensive care use may have previously been under-recognised. In 2009, high ICU use among young to middle aged adults was offset by relatively low use among older adults, and Aboriginal people and pregnant women were substantially over-represented in ICUs. Greater emphasis on prevention of serious illness in Aboriginal people and pregnant women should be a priority in pandemic planning.
    Full-text · Article · Oct 2012 · BMC Public Health
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    • "Influenza virus is a leading cause of morbidity and mortality in older persons. Pneumonia caused by either the influenza virus itself or by secondary bacterial infection is the most serious complication affecting patients with influenza.1,2,7 The clinical presentation of influenza is often complex in elderly patients. "
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    ABSTRACT: Influenza is a well established cause of seasonal hospitalizations and deaths among older persons. However, influenza is frequently underdiagnosed by physicians, because its clinical presentations are often complex, particularly in elderly patients. We report the case of a 78-year-old woman admitted to the emergency department in January 2008 with fever, vomiting, and a history of asthenia and falls in the preceding three days. Diagnosis of influenza at admission was missed. Influenza was diagnosed by direct fluorescent antibody in a sputum specimen four days later, but the evolution was rapidly unfavorable with fatal respiratory distress syndrome. This case illustrates that, during the influenza season, influenza should be suspected in elderly patients admitted to hospital even if they do not present with classical symptoms. Immunofluorescence testing on sputum specimens can provide a rapid diagnosis and merits further evaluation.
    Full-text · Article · Jan 2012 · Clinical Medicine Insights: Case Reports
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