Unmasking influenza virus infection in patients attended to in the emergency department

Implementation and evaluation of a SARI surveillance system in a tertiary hospital in Scotland in 2021/2022

OBJECTIVE

To set up and evaluate a new surveillance system for severe acute respiratory infection (SARI) in Scotland.

STUDY DESIGN

Cross-sectional study and evaluation of surveillance system.

METHODS

The SARI case definition comprised patients aged 16 years or over with an acute respiratory illness presentation requiring testing for influenza and SARS-CoV-2 and hospital admission. Data were collected from SARI cases by research nurses in one tertiary teaching hospital using a bespoke data collection tool from November 2021 to May 2022. Descriptive analyses of SARI cases were carried out. The following attributes of the surveillance system were evaluated according to Centers for Disease Control and Prevention (CDC) guidelines: stability, data quality, timeliness, positive predictive value, representativeness, simplicity, acceptability and flexibility.

RESULTS

The final surveillance dataset comprised 1163 records, with cases peaking in ISO week 50 (week ending 19/12/2021). The system produced a stable stream of surveillance data, with the proportion of SARI records with sufficient information for effective surveillance increasing from 65.4% during the first month to 87.0% over time. Similarly, the proportion where data collection was completed promptly was low initially, but increased to 50%-65% during later periods.

CONCLUSION

SARI surveillance was successfully established in one hospital, but for a national system, additional sentinel hospital sites across Scotland, with flexibility to ensure consistently high data completeness and timeliness are needed. Data collection should be automated where possible, and demands on clinicians minimised. SARI surveillance should be embedded and resourced as part of a national respiratory surveillance strategy.

Management of hospitalized influenza A patients during the season 2018/19 : Comparison of three medical departments and the effect on outcome and antibiotic usage

BACKGROUND

Diagnosis and treatment of influenza patients are often provided across several medical specialties. We compared patient outcomes at an infectious diseases (ID), a rheumatology (Rheu) and a pulmonology (Pul) department.

MATERIAL AND METHODS

In this prospective observational multicenter study we included all influenza positive adults who were hospitalized and treated at flu isolation wards in three hospitals in Vienna during the season 2018/2019.

RESULTS

A total of 490 patients (49% female) with a median age of 73 years (interquartile range [IQR] 61-82) were included. No differences regarding age, sex and most underlying diseases were present at admission. Frequencies of the most common complications differed: acute kidney failure (ID 12.7%, Rheu 21.2%, Pulm 37.1%, p < 0.001), acute heart failure (ID 4.3%, Rheu 17.1%, Pulm 14.4%, p < 0.001) and respiratory insufficiency (ID 45.1%, Rheu 41.5%, Pulm 56.3%, p = 0.030). Oseltamivir prescription was lowest at the pulmonology flu ward (ID 79.6%, Rheu 90.5%, Pulm 61.7%, p < 0.001). In total 176 patients (35.9%) developed pneumonia. Antibiotic selection varied between the departments: amoxicillin/clavulanic acid (ID 28.9%, Rheu 63.8%, Pulm 5.9%, p < 0.001), cefuroxime (ID 28.9%, Rheu 1.3%, Pulm 0%, p < 0.001), 3rd generation cephalosporins (ID 4.4%, Rheu 5%, Pulm 72.5%, p < 0.001), doxycycline (ID 17.8%, Rheu 0%, Pulm 0%, p < 0.001). The median length of stay was significantly different between wards: ID 6 days (IQR 5-8), Rheu 6 days (IQR 5-7) and Pulm 7 days (IQR 5-9.5, p = 0.034). In-hospital mortality was 4.3% and did not differ between specialties.

CONCLUSION

We detected differences in oseltamivir usage, length of in-hospital stay and antibiotic choices for pneumonia. Influenza-associated mortality was unaffected by specialty.

Influenza in carehome residents: applying a conceptual framework to describe barriers to the implementation of guidance on treatment and prophylaxis

BACKGROUND

The European Centre for Disease Prevention and Control, National Institute for Health and Care Excellence and Public Health England have all endorsed the use of antivirals for the treatment and prophylaxis of influenza for care home residents. However, implementing these guidelines in practice is often challenging. This article aims to explore what factors impact the management of care home flu outbreaks in England according to national guidelines and highlight opportunities for change.

METHODS

Qualitative data from notified outbreaks between September 2017 to April 2018 in the South East of England were analyzed, applying the Greenhalgh framework for barriers to guideline implementation. Summary statistics on outbreak characteristics were generated. Stakeholders were mapped out using Eden and Ackermann's grid of interest and influence. A process map was developed to describe operational pathways.

RESULTS

There was often a delay in notifying potential outbreaks to Public Health England. Clinicians cited a lack of robust evidence for the use of antivirals and the available guidelines being too unwieldy as reasons for not implementing prescribing guidance. Many high interests and high influence stakeholders are involved in the sometimes complex care pathway, requiring coordinated work and agreement before antivirals can be prescribed.

CONCLUSIONS

Our findings highlight points in the care pathway that stakeholders can target to improve quality of care and increase the likelihood of national guidance being implemented. The principles described in this article can also be applied to other challenges of translating evidence into practice and cross-organisational working.

Characteristics of patients with Coronavirus Disease 2019 (COVID-19) and seasonal influenza at time of hospital admission: a single center comparative study

BACKGROUND

In the future, co-circulation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza viruses A/B is likely. From a clinical point of view, differentiation of the two disease entities is crucial for patient management. We therefore aim to detect clinical differences between Coronavirus Disease 2019 (COVID-19) and seasonal influenza patients at time of hospital admission.

METHODS

In this single-center observational study, we included all consecutive patients hospitalized for COVID-19 or influenza between November 2019 and May 2020. Data were extracted from a nationwide surveillance program and from electronic health records. COVID-19 and influenza patients were compared in terms of baseline characteristics, clinical presentation and outcome. We used recursive partitioning to generate a classification tree to discriminate COVID-19 from influenza patients.

RESULTS

We included 96 COVID-19 and 96 influenza patients. Median age was 68 vs. 70 years (p = 0.90), 72% vs. 56% (p = 0.024) were males, and median Charlson Comorbidity Index (CCI) was 1 vs. 2 (p = 0.027) in COVID-19 and influenza patients, respectively. Time from symptom onset to hospital admission was longer for COVID-19 (median 7 days, IQR 3-10) than for influenza patients (median 3 days, IQR 2-5, p < 0.001). Other variables favoring a diagnosis of COVID-19 in the classification tree were higher systolic blood pressure, lack of productive sputum, and lack of headache. The tree classified 86/192 patients (45%) into two subsets with ≥80% of patients having influenza or COVID-19, respectively. In-hospital mortality was higher for COVID-19 patients (16% vs. 5%, p = 0.018).

CONCLUSION

Discriminating COVID-19 from influenza patients based on clinical presentation is challenging. Time from symptom onset to hospital admission is considerably longer in COVID-19 than in influenza patients and showed the strongest discriminatory power in our classification tree. Although they had fewer comorbidities, in-hospital mortality was higher for COVID-19 patients.

Respiratory viral infections in the elderly

With the global over 60-year-old population predicted to more than double over the next 35 years, caring for this aging population has become a major global healthcare challenge. In 2016 there were over 1 million deaths in >70 year olds due to lower respiratory tract infections; 13-31% of these have been reported to be caused by viruses. Since then, there has been a global COVID-19 pandemic, which has caused over 2.3 million deaths so far; increased age has been shown to be the biggest risk factor for morbidity and mortality. Thus, the burden of respiratory viral infections in the elderly is becoming an increasing unmet clinical need. Particular challenges are faced due to the interplay of a variety of factors including complex multimorbidities, decreased physiological reserve and an aging immune system. Moreover, their atypical presentation of symptoms may lead to delayed necessary care, prescription of additional drugs and prolonged hospital stay. This leads to morbidity and mortality and further nosocomial spread. Clinicians currently have limited access to sensitive detection methods. Furthermore, a lack of effective antiviral treatments means there is little incentive to diagnose and record specific non-COVID-19 viral infections. To meet this unmet clinical need, it is first essential to fully understand the burden of respiratory viruses in the elderly. Doing this through prospective screening research studies for all respiratory viruses will help guide preventative policies and clinical trials for emerging therapeutics. The implementation of multiplex point-of-care diagnostics as a mainstay in all healthcare settings will be essential to understand the burden of respiratory viruses, diagnose patients and monitor outbreaks. The further development of novel targeted vaccinations as well as anti-viral therapeutics and new ways to augment the aging immune system is now also essential.The reviews of this paper are available via the supplemental material section.

Influenza With and Without Fever: Clinical Predictors and Impact on Outcomes in Patients Requiring Hospitalization

Background

The Infectious Diseases Society of America influenza guidelines no longer require fever as part of their influenza case definition in patients requiring hospitalization. However, the impact of fever or lack of fever on clinical decision-making and patient outcomes has not been studied.

Methods

We conducted a retrospective review of adult patients admitted to our tertiary health service between April 2016 and June 2019 with laboratory-confirmed influenza, with and without fever (≥37.8ºC). Patient demographics, presenting features, and outcomes were analyzed using Pearson's chi-square test, the Wilcoxon rank-sum test, and logistic regression.

Results

Of 578 influenza inpatients, 219 (37.9%) had no fever at presentation. Fever was less likely in individuals with a nonrespiratory syndrome (adjusted odds ratio [aOR], 0.44; 95% CI, 0.26-0.77), symptoms for ≥3 days (aOR, 0.53; 95% CI, 0.36-0.78), influenza B infection (aOR, 0.45; 95% CI, 0.29-0.70), chronic lung disease (aOR, 0.55; 95% CI, 0.37-0.81), age ≥65 (aOR, 0.36; 95% CI, 0.23-0.54), and female sex (aOR, 0.69; 95% CI, 0.48-0.99). Patients without fever had lower rates of testing for influenza in the emergency department (64.8% vs 77.2%; P = .002) and longer inpatient stays (median, 2.4 vs 1.9 days; P = .015). These patients were less likely to receive antiviral treatment (55.7% vs 65.6%; P = .024) and more likely die in the hospital (3.2% vs 0.6%; P = .031), and these differences persisted after adjustment for potential confounders.

Conclusions

Absence of fever in influenza is associated with delayed diagnosis, longer length of stay, and higher mortality.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Sources of viral respiratory infections in Canadian acute care hospital healthcare personnel

BACKGROUND

Viral respiratory illnesses are common causes of outbreaks and can be fatal to some patients.

AIM

To investigate the association between laboratory-confirmed viral respiratory infections and potential sources of exposure during the previous 7 days.

METHODS

In this nested case-control analysis, healthcare personnel from nine Canadian hospitals who developed acute respiratory illnesses during the winters of 2010/11-2013/14 submitted swabs that were tested for viral pathogens. Associated illness diaries and the weekly diaries of non-ill participants provided information on contact with people displaying symptoms of acute respiratory illness in the previous week. Conditional logistic regression assessed the association between cases, who were matched by study week and site with controls with no respiratory symptoms.

FINDINGS

There were 814 laboratory-confirmed viral respiratory illnesses. The adjusted odds ratio (aOR) of a viral illness was higher for healthcare personnel reporting exposures to ill household members [7.0, 95% confidence interval (CI) 5.4-9.1], co-workers (3.4, 95% CI 2.4-4.7) or other social contacts (5.1, 95% CI 3.6-7.1). Exposures to patients with respiratory illness were not associated with infection (aOR 0.9, 95% CI 0.7-1.2); however, healthcare personnel with direct patient contact did have higher odds (aOR 1.3, 95% CI 1.1-1.6). The aORs for exposure and for direct patient contact were similar for illnesses caused by influenza.

CONCLUSION

Community and co-worker contacts are important sources of viral respiratory illness in healthcare personnel, while exposure to patients with recognized respiratory infections is not associated. The comparatively low risk associated with direct patient contact may reflect transmission related to asymptomatic patients or unrecognized infections.

Aging and influenza vaccine-induced immunity

Immunosenescence is defined as the progressive deterioration of the immune system with aging. Immunosenescence stifles the generation of protective B and T cell-mediated adaptive immunity in response to various pathogens, resulting in increased disease susceptibility and severity in the elderly population. In particular, immunosenescence has major impacts on the phenotype, function, and receptor repertoire of B and T cells in the elderly, hindering protective responses induced by seasonal influenza virus vaccination. In order to overcome the detrimental impacts of immunosenescence on protective immunity to influenza viruses, we review our current understanding of the effects of aging on adaptive immune responses to influenza and discuss current and future avenues of vaccine research for eliciting more potent anti-influenza immunity in the elderly.

Is there a clinical difference between influenza A and B virus infections in hospitalized patients? : Results after routine polymerase chain reaction point-of-care testing in the emergency room from 2017/2018

PURPOSE

The clinical presentation, complications and mortality in molecularly confirmed influenza A and B infections were analyzed.

METHODS

This retrospective observational single-centre study included all influenza positive patients older than 18 years who were hospitalized and treated at the flu isolation ward during 2017/2018. The diagnosis was based on point-of-care tests with the Alere^TM.

RESULTS

Of the 396 patients tested positive for influenza, 24.2% had influenza A and 75.8% influenza B. Influenza A patients were younger (median age 67.5 years vs. 77 years, p < 0.001), were more often smokers (27.7% vs. 16.8%, p = 0.021), had chronic pulmonary diseases more frequently (39.6% vs. 26.3%, p = 0.013), presented with a higher body temperature (38.6 °C vs. 38.3 °C, p = 0.004), leucocyte count (8 G/L vs. 6.8 G/L, p = 0.002), C‑reactive protein (CRP) level (41 mg/l vs. 23 mg/l, p < 0.001) and had dyspnea more often (41.7% vs. 28%, p = 0.012). Influenza B patients had an underlying chronic kidney disease in 37% vs. 18.8% (p < 0.001) and presented with vomiting on admission more frequently (21.7% vs. 11.5%, p = 0.027). Influenza A patients were admitted for 8 days vs. 7 days (p = 0.023). There were no differences in the rate of complications; however, 22 (5.6%) patients died during the hospital stay. The in-hospital mortality was higher in influenza A patients (8.3% vs 4.7%, p = 0.172).

CONCLUSION

Some differences were found between influenza A and B virus infections but symptoms were overlapping, which necessitates polymerase chain reaction point-of-care testing for accurate diagnosis. Influenza A was a more severe disease than influenza B during the period 2017/2018.

Influenza virus infection: an approach to identify predictors for in-hospital and 90-day mortality from patients in Vienna during the season 2017/18

BACKGROUND

Seasonal influenza outbreaks are associated with increased mortality and hospitalisation rates. Herein we tried to identify predictors of mortality in hospitalised patients with influenza virus infection.

MATERIALS/METHODS

In this exploratory retrospective observational single-centre-study we included all influenza-positive patients older than 18 years who were hospitalised and treated at the flu-isolation-ward during the influenza season 2017/18. Diagnosis was based on point-of-care-test with the Alere™ i. First we performed χ² tests and Mann-Whitney U tests to identify predictors of mortality. Significant variables were used in a stepwise-forward-logistic-regression-model to predict in-hospital and 90-day mortality.

RESULTS

Of the 396 patients who tested positive for influenza 96 (24.2%) had influenza A and 300 (75.8%) influenza B. Twenty-two (5.6%) died in hospital and the 90-day mortality rate was 9.4%. In the stepwise logistic regression older age (OR 1.1 per year 95% CI 1.03-1.17), history of atrial fibrillation (OR 5.91 95% CI 1.91-18.34), dementia (OR 3.98 95% CI 1.24-12.78), leucocyte count (OR 1.11 per G/L 95% CI 1.03-1.20), pneumonia (OR 4.39 95% CI 1.44-13.39) and acute heart failure (OR 23.15 95% CI 4.33-123.76) increased the risk of in-hospital mortality. The risk for 90-day mortality was increased by older age (OR 1.04 per year 95% CI 1.01-1.07), history of atrial fibrillation (OR 3.1, 95% CI 1.36-7.05), history of congestive heart failure (OR 4.7 95% CI 1.94-11.48), pneumonia (OR 3.2 95% CI 1.45-6.91) and decreased by statin use (OR 0.28 95% CI 0.10-0.78).

CONCLUSIONS

Older age, history of atrial fibrillation and pneumonia are associated with increased risk of influenza-associated in-hospital and 90-day mortality. Statin use may decrease 90-day mortality.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Influenza virus infections among patients attending emergency department according to main reason to presenting to ED: A 3-year prospective observational study during seasonal epidemic periods

OBJECTIVE

The role of influenza virus in patients presenting at ED during seasonal-epidemic periods has not previously been specified. Our objective was to determine its frequency according to clinical presentation.

METHODS

This is a prospective observational study conducted during three-consecutive seasonal Influenza epidemics (2013-2015), including patients presenting i) community-acquired pneumonia (CAP); ii) severe acute symptoms (SAS): respiratory failure (RF), hemodynamic failure (HF), cardiac failure (CF), and miscellaneous symptoms (M); iii) symptoms suggesting influenza (PSSI). Patients were tested for influenza using specific PCR on naso-pharyngeal swabs.

RESULTS

Of 1,239 patients, virological samples were taken from 784 (63.3%), 213 (27.2%) of whom were positive for the influenza virus: CAP 52/177 (29.4%), SAS 115/447 (25.7%) and PSSI 46/160 (28.8%) (p = 0.6). In the SAS group positivity rates were: RF 76/263 (28.9%), HF 5/29 (17.2%), CF 15/68 (22.1%), and M 19/87 (21.8%) (p = 0.3). Among the major diagnostic categories, the influenza virus positivity rates were: asthma 60/231 (26%), acute exacerbation of chronic obstructive pulmonary disease 18/86 (20.9%), HIV 5/21 (23.8%) and cardiac failure 33/131 (25.2%). The positivity of the samples has not been associated (p>0.1) nor the presence of signs of severity or admission rate in medical ward nor intensive care unit.

CONCLUSIONS

Our results indicate that during seasonal influenza epidemics, Influenza virus-positivity rate is similar in patients attending ED for influenza-compatible clinical features, patients with acute symptoms including pneumonia, respiratory, hemodynamic and cardiac distress, and patients presenting for acute decompensation of chronic respiratory and cardiac diseases.

Is Influenza an Influenza-Like Illness? Clinical Presentation of Influenza in Hospitalized Patients

Background.

Early recognition of influenza virus infection in hospitalized patients can prevent nosocomial transmission.

Objective.

To determine the clinical presentation of influenza in hospitalized patients.

Design.

Case series. Data were collected retrospectively from medical records and included demographic information, comorbidities, clinical symptoms and signs, microbiologic test results, and outcomes (including pneumonia and intensive care unit [ICU] admission).

Setting.

A 1,400-bed teaching hospital.

Patients.

A total of 207 inpatients who received a diagnosis of influenza virus infection during 3 seasons from 2000 to 2003.

Results.

Over the course of 3 seasons, 207 patients received a diagnosis of influenza (186 were infected with influenza A virus, and 21 were infected with influenza B virus). The most commonly reported symptoms were cough (186 patients [90%]) and subjective fever (137 patients [66%]); 124 patients (60%) had a documented temperature of 37.8°C or greater before influenza was diagnosed. Sore throat was uncommon (44 patients [21%]). Centers for Disease Control and Prevention (CDC) criteria for influenza-like illness (ILI)–temperature 37.8°C or greater and either cough or sore throat–were met by 107 patients (51%). There were no differences in the proportion of patients who met ILI criteria with respect to age, sex, season, influenza virus type, or time to diagnosis in the hospital. Most patients (150 [72%]) received acetaminophen. Only 41 patients (20%) had positive results of clinical cultures; 178 patients (86%) received antibiotic therapy. Fifty-six patients (27%) had pneumonia: 36 (17%) required admission to the ICU, and 25 (12%) required ventilatory support. Patients with pulmonary disease were more likely to require ventilatory support (12 [26%] vs 13 [8%]; P = .003).

Conclusions.

Only half of hospitalized patients with influenza met CDC criteria for ILI. These criteria may be more appropriate in outpatient settings. A high index of suspicion is needed to recognize influenza in hospitalized patients.

Clinical predictors for laboratory-confirmed influenza infections: exploring case definitions for influenza-like illness

OBJECTIVE

To identify clinical signs and symptoms (ie, "terms") that accurately predict laboratory-confirmed influenza cases and thereafter generate and evaluate various influenza-like illness (ILI) case definitions for detecting influenza. A secondary objective explored whether surveillance of data beyond the chief complaint improves the accuracy of predicting influenza.

DESIGN

Retrospective, cross-sectional study.

SETTING

Large urban academic medical center hospital.

PARTICIPANTS

A total of 1,581 emergency department (ED) patients who received a nasopharyngeal swab followed by rRT-PCR testing between August 30, 2009, and January 2, 2010, and between November 28, 2010, and March 26, 2011.

METHODS

An electronic surveillance system (GUARDIAN) scanned the entire electronic medical record (EMR) and identified cases containing 29 clinical terms relevant to influenza. Analyses were conducted using logistic regressions, diagnostic odds ratio (DOR), sensitivity, and specificity.

RESULTS

The best predictive model for identifying influenza for all ages consisted of cough (DOR=5.87), fever (DOR=4.49), rhinorrhea (DOR=1.98), and myalgias (DOR=1.44). The 3 best case definitions that included combinations of some or all of these 4 symptoms had comparable performance (ie, sensitivity=89%-92% and specificity=38%-44%). For children <5 years of age, the addition of rhinorrhea to the fever and cough case definition achieved a better balance between sensitivity (85%) and specificity (47%). For the fever and cough ILI case definition, using the entire EMR, GUARDIAN identified 37.1% more influenza cases than it did using only the chief complaint data.

CONCLUSIONS

A simplified case definition of fever and cough may be suitable for implementation for all ages, while inclusion of rhinorrhea may further improve influenza detection for the 0-4-year-old age group. Finally, ILI surveillance based on the entire EMR is recommended.

Use of simple clinical and laboratory predictors to differentiate influenza from dengue and other febrile illnesses in the emergency room

Background

Clinical differentiation of influenza from dengue and other febrile illnesses (OFI) is difficult, and available rapid diagnostic tests have limited sensitivity.

Methods

We conducted a retrospective study to compare clinical and laboratory findings between (i) influenza and dengue and (ii) influenza and OFI.

Results

Of 849 enrolled patients, the mean time between illness onset and hospital presentation was 1.7, 3.7, and 3 days for influenza, dengue, and OFI, respectively. Among pediatric patients (≤18 years) (445 influenza, 24 dengue, and 130 OFI), we identified absence of rashes, no leukopenia, and no marked thrombocytopenia (platelet counts <100 × 10⁹ cells/L) as predictors to distinguish influenza from dengue, whereas rhinorrhea, malaise, sore throat, and mild thrombocytopenia (platelet counts 100-149 × 10⁹/L) were predictors that differentiated influenza from OFI. Among adults (>18 years) (81 influenza, 124 dengue, and 45 OFI), no leukopenia and no marked thrombocytopenia distinguished influenza from dengue, while rhinorrhea and malaise differentiated influenza from OFI. A diagnostic algorithm developed to distinguish influenza from dengue using rash, leukopenia, and marked thrombocytopenia showed >90% sensitivity to identify influenza in pediatric patients.

Conclusions

This study identified simple clinical and laboratory parameters that can assist clinicians to distinguish influenza from dengue and OFI. These findings may help clinicians diagnose influenza and facilitate appropriate management of affected patients, particularly in resource-poor settings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-014-0623-z) contains supplementary material, which is available to authorized users.

Five years of hospital based surveillance of influenza-like illness and influenza in a short-stay geriatric unit

Background

Data on influenza in the healthcare setting are often based on retrospective investigations of outbreaks and a few studies described influenza during several consecutive seasons.

The aim of the present work is to report data on influenza like illness (ILI) and influenza from 5-year prospective surveillance in a short-stay geriatrics unit.

Findings

A short stay geriatrics unit underwent 5 years of ILI surveillance from November 2004 to March 2009, with the aim of describing ILI in a non-outbreak context. The study was proposed to patients who presented ILI, defined as fever >37.8°C or cough or sore throat. Among 1,353 admitted patients, 115 presented an ILI, and 34 had hospital-acquired ILI (HA-ILI). Influenza was confirmed in 23 patients, 13 of whom had been vaccinated. Overall attack rates were 2.78% and 0.02% for HA-ILI and HA-confirmed influenza respectively, during the 5 seasons.

Conclusions

This 5-year surveillance study supports the notion that influenza infections are common in hospitals, mostly impacting the elderly hospitalized in short-stay units. It highlights the need for appropriate control measures to prevent HA-ILI in geriatric units and protect elderly patients.

Delay in diagnosis of influenza virus in an elderly hospitalized patient: a fatal outcome

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.

Predictors of pandemic influenza infection in adults presenting to two urban emergency departments, Toronto, 2009

OBJECTIVE

Identifying features that differentiate patients with H1N1 influenza infection from those with other conditions may assist clinical decision making during waves of pandemic influenza activity.

METHODS

From April 27 to June 15, 2009, nasopharyngeal swabs were obtained from all adults presenting to two urban emergency departments (EDs) with illness including fever or respiratory symptoms. H1N1 infection was detected by reverse transcriptase-polymerase chain reaction. Chart review was performed to compare cases of H1N1 influenza (n  =  117) to matched controls.

RESULTS

The median age of cases was 35 years versus 50 years for controls (p < .001). In those with pre-existing conditions, asthma was present in 31% of cases versus 14% of controls (OR 2.6, 95% CI 1.3-5.4). Cough (OR 7.8, 95% CI 3.2-19), fever (OR 3.0, 95% CI 1.7-5.4), headache (OR 2.0, 95% CI 1.2-3.2), and myalgias (OR 1.9, 95% CI 1.2-3.1) were significantly more common in H1N1 cases. The median white blood cell count was 5.7 × 109/mL versus 10.9 × 109/mL (p < .001). The combination of fever and cough had an OR of 5.3. Fever, cough, low white blood cell (WBC) count, and tachycardia had the highest OR at 11. The absence of both fever and cough had a negative predictive value of 99%, but this occurred in only 8% of controls.

CONCLUSION

In patients presenting to the ED, the combination of fever, cough, tachycardia, and WBC count < 10 × 109/mL was suggestive of H1N1 influenza infection. However, clinical features could not reliably distinguish influenza from other acute respiratory illnesses in adult ED patients.

Differences in clinical predictors of influenza in adults and children with influenza-like illness

Influenza contributes significantly to morbidity and mortality in the winter season. The aim of the study was to identify clinical signs and symptoms most predictive of influenza infection in children and adults with influenza-like illness. A prospective systematic sampling analysis of clinical data collected through sentinel surveillance system for influenza in 32 primary care centers and one tertiary care hospital in Slovenia during two consecutive influenza seasons (2004/2005 and 2005/2006) was carried out. Children and adults who had influenza-like illness, defined as febrille illness with sudden onset, prostration and weakness, muscle and joint pain and at least (cough, sore throat, coryza) were included and tested for influenza A and B virus, adenovirus, respiratory syncytial virus and enterovirus by RT-PCR. Clinical data were evaluated in statistical models to identify the best predictors for the confirmation of influenza for children (under age of 15) and adults. Of 1,286 patients with influenza-like symptoms in both seasons 211 were confirmed to have influenza A or B alone and compared to 780 influenza-negative patients. A fever over 38°C, chills, headache, malaise and sore eyes revealed a significant association with positive RT-PCR test for influenza virus in children. In adults, only three symptoms were significantly related to PCR-confirmed influenza infection: fever, cough and abnormal breath sounds. The stepwise logistic regression analysis showed that four symptoms predicted influenza in children: fever (38°C or more) (p=0.010), headache (p=0.030), cough (p=0.044) and absence of abnormal breathing sounds (p=0.015) with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 5.1%, 98.1%, 57.1% and 80.1%, respectively. For adults, the strongest impact on influenza positivity was found for fever (p=0.008) and cough (p=0.085). The model for adults had less favorable characteristics, with sensitivity, specificity, PPV and NPV of 0%, 100%, 0% and 76.4%, respectively. Differences in clinical predictors of influenza in children compared to adults were found. The model for adults was acceptable but not a good one. The model for children was found to be more reliable than the prediction model for adults.

Seasonal influenza in adults and children--diagnosis, treatment, chemoprophylaxis, and institutional outbreak management: clinical practice guidelines of the Infectious Diseases Society of America

Guidelines for the treatment of persons with influenza virus infection were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic issues, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal (interpandemic) influenza. They are intended for use by physicians in all medical specialties with direct patient care, because influenza virus infection is common in communities during influenza season and may be encountered by practitioners caring for a wide variety of patients.

Case-control study of clinical features of influenza in hospitalized patients

BACKGROUND

The symptoms of influenza infection in outpatients are well described. The Centers for Disease Control and Prevention (CDC) definition of an influenza-like illness (ILI) includes fever and cough or sore throat. Few data exist on the clinical presentation of influenza in hospitalized patients, which may be distinct from the clinical presentation of influenza in ambulatory patients because of underlying medical conditions and medications.

DESIGN

Retrospective case-control study.

SETTING

A 1,250-bed urban teaching hospital.

PATIENTS

A total of 369 patients were admitted to the general medicine wards during 3 consecutive influenza seasons (2001-2004): 123 case patients with laboratory-confirmed influenza that was diagnosed during routine medical care and 246 control patients with active surveillance culture results negative for influenza.

METHODS

Data on demographic characteristics, comorbidities, and signs and symptoms were obtained from a review of the medical records of the case and control patients. Analysis included stratified analysis and logistic regression.

RESULTS

Cough, coryza, sore throat, and fever were more common in patients with influenza infection. The CDC's definition of an ILI had a sensitivity of 43% and specificity of 86% in the study population, with a crude odds ratio (OR) of 4.7 (95% confidence interval [CI], 2.8-7.8). The sensitivity of the CDC's definition of an ILI decreased to 21% among asthmatic patients, who had similar rates of fever and/or ILI with or without influenza. By logistic regression, ILI was strongly associated with influenza infection in patients without asthma (adjusted OR, 7.5 [95% CI, 4.1-13.7]) but not in patients with asthma (adjusted OR, 1.1 [95% CI, 0.13-10]). The positive predictive value of an ILI in asthmatic patients was 50%.

CONCLUSIONS

The CDC's definition of an ILI lacks sensitivity among hospitalized patients, and the presence of an ILI is not associated with influenza infection in asthmatic patients.

Increased complaints of fever in the emergency room can identify influenza epidemics

BACKGROUND

In developing countries, it may be easier to use the reasons why patients come to the emergency room (ER) instead of sentinel practices to identify influenza epidemics.

METHODS

We studied the reasons why adult patients present to the ER in order to attempt to predict increased hospital activity as a result of influenza. The daily frequency of presenting symptoms during the 30 days of maximal influenza activity was compared to the other days of the study period (335 days).

RESULTS

During the influenza period, more patients presented with fever, syncope or near syncope, cough, asthma attack, and paralysis than on the days outside of this period. On 50% of the days, eight or more patients presented with fever, an 8.36 (95% CI=4.6-15.19) higher frequency than during the rest of the year. During the subsequent year, days with excess presentations by patients with a principal complaint of fever predicted increased hospital activity due to influenza with no false-positive periods.

CONCLUSIONS

We conclude that an increase in the number of patients presenting to the ER complaining of fever can identify increased hospital influenza activity.

Hospital-acquired influenza: a synthesis using the Outbreak Reports and Intervention Studies of Nosocomial Infection (ORION) statement

Nosocomial influenza outbreaks occur in almost all types of hospital wards, and their consequences for patients and hospitals in terms of morbidity, mortality and costs are considerable. The source of infection is often unknown, since any patient, healthcare worker (HCW) or visitor is capable of transmitting it to susceptible persons within hospitals. Nosocomial influenza outbreak investigations should help to identify the source of infection, prevent additional cases, and increase our knowledge of disease control to face future outbreaks. However, such outbreaks are probably underdetected and underreported, making routes of transmission difficult to track and describe with precision. In addition, the absence of standardised information in the literature limits comparison between studies and better understanding of disease dynamics. In this study, reports of nosocomial influenza outbreaks are synthesised according to the ORION guidelines to highlight existing knowledge in relation to the detection of influenza cases, evidence of transmission between patients and HCWs and measures of disease incidence. Although a body of evidence has confirmed that influenza spreads within hospitals, we should improve clinical and virological confirmation and initiate active surveillance and quantitative studies to determine incidence rates in order to assess the risk to patients.

Influenza and pneumococcal vaccinations in the emergency department

Influenza and pneumococcal pneumonia remain among the most significant causes of morbidity and mortality of any of the infectious disease emergencies presenting to emergency departments (EDs). Because the ED has become a recommended location at which immunizations have been administered to prevent several infections, pneumococcal and influenza vaccinations can have an impact on the care of ED patients. ED personnel are uniquely positioned to vaccinate a substantial number of patients who would not otherwise be vaccinated, including many high-risk populations. In addition to decreasing vaccine-preventable mortality and morbidity from influenza and pneumococcal diseases, EDs that implement and monitor a systematic approach to these vaccinations can attenuate ED overcrowding and facilitate patient flow. ED vaccination strategies have been proved to be successful and reimbursable and are advocated by several major clinical practice advisory groups.

Critical Care Pandemic Preparedness Primer

The first half decade of the 21^st century has brought with it infectious outbreaks such as severe acute respiratory syndrome (SARS) [1], bioterrorism attacks with anthrax [2], and the spread of H5N1 influenza A in birds across Asia and Europe [3, 4] sparking concerns reminiscent of the days of the Black Plague. These events, in the context of an instantaneous global-media world, have placed an unprecedented emphasis on preparing for a human influenza pandemic [5, 6]. Although some argue that the media have exaggerated the threat, the warnings of an impending pandemic are not without foundation given the history of past influenza pandemics [7], incidence of H5N1 infections among humans [8], and the potential impact of a pandemic. Reports of the 1918 pandemic vary, but most suggested that approximately one third of the world’s population was infected with 50 to 100 million deaths [9]. Computer modeling of a moderate pandemic, less severe then in 1918, in the province of Ontario, Canada predicts 73,252 admissions of influenza patients to hospitals over a 6-week period utilizing 72% of the hospital capacity, 171% of intensive care unit (ICU) capacity, and 118% of current ventilator capacity. Pandemic modeling by the Australian and New Zealand Intensive Care Society also showed that critical care resources would be overwhelmed by even a moderate pandemic [10]. This chapter will provide intensivists with a review of the basic scientific and clinical aspects of influenza as well as an introduction to pandemic preparedness.

Critical Care Pandemic Preparedness Primer

The first half decade of the 21^st century has brought with it infectious outbreaks such as severe acute respiratory syndrome (SARS) [1], bioterrorism attacks with anthrax [2], and the spread of H5N1 influenza A in birds across Asia and Europe [3, 4] sparking concerns reminiscent of the days of the Black Plague. These events, in the context of an instantaneous global-media world, have placed an unprecedented emphasis on preparing for a human influenza pandemic [5, 6]. Although some argue that the media have exaggerated the threat, the warnings of an impending pandemic are not without foundation given the history of past influenza pandemics [7], incidence of H5N1 infections among humans [8], and the potential impact of a pandemic. Reports of the 1918 pandemic vary, but most suggested that approximately one third of the world’s population was infected with 50 to 100 million deaths [9]. Computer modeling of a moderate pandemic, less severe then in 1918, in the province of Ontario, Canada predicts 73,252 admissions of influenza patients to hospitals over a 6-week period utilizing 72% of the hospital capacity, 171% of intensive care unit (ICU) capacity, and 118% of current ventilator capacity. Pandemic modeling by the Australian and New Zealand Intensive Care Society also showed that critical care resources would be overwhelmed by even a moderate pandemic [10]. This chapter will provide intensivists with a review of the basic scientific and clinical aspects of influenza as well as an introduction to pandemic preparedness.

Communicable respiratory threats in the ED: tuberculosis, influenza, SARS, and other aerosolized infections

Respiratory infections are the most common communicable infectious diseases. EDs are the front line for patients with respiratory infections because of their acute nature and because the ED is the principal site of health care for those at highest risk. These diseases include influenza, tuberculosis, and measles, together accounting for 25% of infectious causes of death worldwide. These are emerging and biothreat agents that follow the same route of transmission, such as pneumonic plague. We discuss epidemiology, pathogenesis, diagnosis, and treatment of each agent. Emphasis is on the ED's role as a public health prevention arena, with attention to education and disease prevention, early identification of disease in patients at risk, and reduction of illnesses.