Swine Influenza (H1N1) pneumonia: clinical considerations

SARS-CoV-2 versus Influenza A Virus: Characteristics and Co-Treatments

For three years, the novel coronavirus disease 2019 (COVID-19) pandemic, caused by infection of the SARS-CoV-2 virus, has completely changed our lifestyles and prepared us to live with this novel pneumonia for years to come. Given that pre-existing flu is caused by the influenza A virus, we have begun unprecedently co-coping with two different respiratory diseases at the same time. Hence, we draw a comparison between SARS-CoV-2 and influenza A virus based on the general characteristics, especially the main variants’ history and the distribution of the two viruses. SARS-CoV-2 appeared to mutate more frequently and independently of locations than the influenza A virus. Furthermore, we reviewed present clinical trials on combined management against COVID-19 and influenza in order to explore better solutions against both at the same time.

New endemic and pandemic pathologies with interhuman airborne transmission through ear, nose and throat anatomical sites

The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has once again stigmatised the importance of airborne pathogens and their clinical, social and public health impact. Respiratory viruses are transmitted between individuals when the pathogen is released from the upper airways or from the lower respiratory tract of an infected individual. Airborne transmission is defined as the inhalation of the infectious aerosol, named droplet nuclei which size is smaller than 5 mm and that can be inhaled at a distance up to 2 metres. This route of transmission is relevant for viral respiratory pathogens, including severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome (MERS)-CoV, influenza virus, human rhinovirus, respiratory syncytial virus (RSV) and other respiratory virus families that differ in viral and genomic structures, susceptibility of a population to the infection, severity, transmissibility, ways of transmission and seasonal recurrence. Human respiratory viruses generally infect cells of the upper respiratory tract, eliciting respiratory signs and symptoms, sometimes without the possibility to differentiate them clinically. As seen by the current Coronavirus Disease 2019 (COVID-19) pandemic, human respiratory viruses can substantially contribute to increased morbidity and mortality, economic losses and, eventually, social disruption. In this article, we describe the structural, clinical and transmission aspects of the main respiratory viruses responsible for endemic, epidemic and pandemic infections.

HD-13 Induces Swine Pneumonia Progression via Activation of TLR9

Swine pneumonia commonly known as swine pasteurellosis is an infectious disease of swine caused by Pasteurella multocida infection. It has been reported that Toll-like receptors (TLRs) play a vital role in swine pneumonia progression. However, the underlying mechanism has not been elucidated. This research was aimed at investigating the molecular mechanism by which TLR9 regulates swine pneumonia progression. Our findings illustrated that the HD-13 strain of Pasteurella multocida D (HD-13) accelerated TLR9 expression in porcine alveolar macrophage 3D4/21 cells; HD-13 activated the inflammatory response via accelerating TLR9 expression. Mechanistically, HD-13 activated mitogen-activated protein kinase (MAPK) and nuclear factor kB (NF-κB) signals. In conclusion, HD-13 may activate MAPK and NF-κB pathways via accelerating TLR9 expression, thereby accelerating the inflammatory response in the progression of swine pneumonia. TLR9 may serve as a novel therapeutic target for swine pneumonia. Our research may provide a theoretical basis for the prevention and treatment of swine pneumonia.

The application of lymphocyte*platelet and mean platelet volume/platelet ratio in influenza A infection in children

Background

To explore the characteristics and regularity of complete blood count (CBC) changes among influenza A–positive child patients and to discover parameters that can help with the diagnosis and differential diagnosis.

Methods

One hundred and ninety‐one influenza A–positive children, two hundred and nineteen influenza A–negative children with influenza‐like symptoms, and two hundred and forty‐seven healthy children were included in this study. They were divided into three groups: influenza A–positive patient group, influenza A–negative patient group, and control group. Reverse transcriptase polymerase chain reaction testing and Sysmex XS‐800i hematology analyzer were used to obtain influenza A and CBC results, respectively. CBC along with parameters including lymphocyte‐to‐monocyte ratio (LMR), neutrophil‐to‐lymphocyte ratio (NLR), platelet‐to‐lymphocyte ratio (PLR), mean platelet volume/platelet ratio (MPV/PLT), and lymphocyte*platelet (LYM*PLT) was calculated and recorded for each child. The differences in these parameters among different groups were tested with SPSS 15.0. The diagnostic values were also evaluated.

Results

The LYM and PLT of child patients with influenza A were significantly lower than those of both influenza A–negative patients with influenza‐like symptoms and healthy controls. Among all the parameters, LYM*PLT has the largest area under the curve and the highest diagnostic value, followed by MPV/PLT. Compared with using LMR or MPV/PLT, the diagnostic value of using LYM alone was, on the contrary, higher.

Conclusions

Low LYM*PLT and high MPV/PLT may indicate influenza A infection in children with influenza‐like symptoms, which can be a useful indicator for diagnosis and differentiation of influenza A infection.

Legionnaire's Disease and its Mimics: A Clinical Perspective

Whenever the cardinal manifestations of a disorder occur in similar disorders, there is potential for a disease mimic. Legionnaire's disease has protean manifestations and has the potential to mimic or be mimicked by other community acquired pneumonias (CAPs). In CAPs caused by other than Legionella species, the more characteristic features in common with legionnaire's disease the more difficult the diagnostic conundrum. In hospitalized adults with CAP, legionnaire's disease may mimic influenza or other viral pneumonias. Of the bacterial causes of CAP, psittacosis and Q fever, but not tularemia, are frequent mimics of legionnaire's disease.

Hematologic parameters to predict negative cerebrospinal fluid examination results among neurologically intact patients who underwent lumbar puncture on suspicion of central nervous system infection

Objective

Cerebrospinal fluid (CSF) examination is mandatory whenever central nervous system (CNS) infection is suspected. However, pleocytosis is not detected in a substantial number of suspected patients who undergo CSF examination. This study aimed to identify parameters that can aid in predicting negative CSF examination results (defined as a white blood cell count of <5 cells/high-power field).

Methods

The study included 101 neurologically intact patients who underwent lumbar puncture because of suspicion of CNS infection. Patients were divided into negative and positive CSF examination groups, and their initial blood tests were comparatively analyzed.

Results

The negative group had a significantly higher proportion of neutrophils in white blood cells (81.5% vs. 75.8%, P=0.012), lower proportion of lymphocytes in white blood cells (9.3% vs. 16.7%, P=0.001), a higher neutrophil-to-lymphocyte ratio (9.1 vs. 4.4, P=0.001), a lower lymphocyte-to-monocyte ratio (1.6 vs. 2.4, P=0.008), and a higher C-reactive protein level (21.0 vs. 5.0 mg/L, P<0.001) than the positive group. In the receiver-operating characteristic analysis, neutrophil-to-lymphocyte ratio and C-reactive protein had an area under the curve of >0.7, and the best cutoff values were 6.0 (accuracy 70.3%) and 12.7 mg/L (accuracy 76.2%), respectively.

Conclusion

The neutrophil-to-lymphocyte ratio ≥6 and C-reactive protein level ≥12.7 mg/L was significantly associated with negative CSF examination result.

The clinical usefulness of lymphocyte:monocyte ratios in differentiating influenza from viral non-influenza-like illnesses in hospitalized adults during the 2015 influenza A (H3N2) epidemic: the uniqueness of HPIV-3 mimicking influenza A

During influenza epidemics, influenza-like illnesses (ILIs) viruses cocirculate with influenza strains. If positive, rapid influenza diagnostic tests (RIDTs) identify influenza A/B, but false-negative RIDTs require retesting by viral polymerase chain reaction (PCR). Patient volume limits testing during influenza epidemics, and non-specific laboratory findings have been used for presumptive diagnosis pending definitive viral testing. In adults, the most useful laboratory abnormalities in influenza include relative lymphopenia, monocytosis, and thrombocytopenia. Lymphocyte:monocyte (L:M) ratios may be even more useful. L:M ratios <2 have been used as a surrogate marker for influenza, but there are no longitudinal data on L:M ratios in hospitalized adults with viral ILIs. During the 2015 influenza A (H3N2) epidemic at our hospital, we reviewed our experience with L:M ratios in 37 hospitalized adults with non-influenza viral ILIs. In hospitalized adults with non-influenza A ILIs, the L:M ratios were >2 with human metapneumovirus (hMPV), rhinoviruses/enteroviruses (R/E), and respiratory syncytial virus (RSV), but not human parainfluenza virus type 3 (HPIV-3), which had L:M ratios <2. HPIV-3, like influenza, was accompanied by L:M ratios <2, mimicking influenza A (H3N2). In influenza A admitted adults, L:M ratios <2 did not continue for >3 days, whereas with HPIV-3, L:M ratios <2 persisted for >3 days of hospitalization.

During influenza season: all influenza-like illnesses are not due to influenza: dengue mimicking influenza

BACKGROUND

During influenza season, many patients present to the emergency department (ED) for evaluation with influenza-like illnesses (ILIs). ILIs are commonly due to influenza A or B, but other infections may mimic influenza in their clinical presentation. With the high volume of ILIs presenting to the ED during influenza season, the ED physician should be alert to other infections masquerading as influenza.

CASE REPORT

We report an interesting case of a 31-year-old female who presented with an ILI during influenza season. She had recently been in contact with multiple people with influenza. Her nonspecific laboratory tests done in the ED were consistent with influenza, except for a highly elevated serum ferritin level. The serum ferritin level was the key finding that led to the correct diagnosis of dengue fever, which she acquired during a recent trip to Haiti. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: During influenza season, facing high patient volumes of ILIs in the ED, the ED physician needs to be aware of clinical features in ILIs that may suggest a mimic of influenza.

Middle East respiratory syndrome (MERS): a new zoonotic viral pneumonia

Coronaviruses have traditionally been associated with mild upper respiratory tract infections throughout the world. In the fall of 2002, a new coronavirus emerged in in Asia causing severe viral pneumonia, i.e., severe acute respiratory syndrome (SARS). Nearly a decade following the SARS epidemic, a new coronavirus causing severe viral pneumonia has emerged, i.e., middle east respiratory syndrome (MERS). Since the initial case of MERS-CoV occurred in June of 2012 in Saudi Arabia there have been 688 confirmed cases and 282 deaths in 20 countries.

 

Although both SARS and MERS are caused by coronaviruses, SARS was characterized by efficient human transmission and relatively low mortality rate. In contrast, MERS is relatively inefficiently transmitted to humans but has a high mortality rate. Given the potential overlap in presentation and manifestation, it is important to understand the clinical and epidemiologic differences between MERS, SARS and influenza.

Influenza vaccination accelerates recovery of ferrets from lymphopenia

Ferrets are a useful animal model for human influenza virus infections, since they closely mimic the pathogenesis of influenza viruses observed in humans. However, a lack of reagents, especially for flow cytometry of immune cell subsets, has limited research in this model. Here we use a panel of primarily species cross-reactive antibodies to identify ferret T cells, cytotoxic T lymphocytes (CTL), B cells, and granulocytes in peripheral blood. Following infection with seasonal H3N2 or H1N1pdm09 influenza viruses, these cell types showed rapid and dramatic changes in frequency, even though clinically the infections were mild. The loss of B cells and CD4 and CD8 T cells, and the increase in neutrophils, were especially marked 1–2 days after infection, when about 90% of CD8+ T cells disappeared from the peripheral blood. The different virus strains led to different kinetics of leukocyte subset alterations. Vaccination with homologous vaccine reduced clinical symptoms slightly, but led to a much more rapid return to normal leukocyte parameters. Assessment of clinical symptoms may underestimate the effectiveness of influenza vaccine in restoring homeostasis.

Report on influenza A and B viruses: their coinfection in a Saudi leukemia patient

PURPOSE

Influenza A and B viruses are the leading cause of respiratory infections in children worldwide, particularly in developing countries. There is a lack of data on coinfection of influenza A and B viruses circulating in Saudi Arabia. In this study, we aimed to identify the circulation of influenza viruses that contribute to respiratory tract infections in Saudi children.

METHODS

We collected 80 nasopharyngeal aspirates (NPAs) from hospitalized children with acute respiratory illness (ARI) at Riyadh during the period extended from October 2010 till April 2011. Samples were tested for the common respiratory viruses including influenza viruses by RT-PCR.

RESULTS

Overall, 6 samples were found positive for influenza A and/or B viruses. Among these positive clinical samples, only one collected sample from a female one-year-old immunocompromised child with leukemia showed a coinfection with influenza A and B viruses. In present study coinfection was confirmed by inoculation of the clinical specimen in specific pathogenfree embryonating chicken eggs and identification of the virus isolates by hemagglutination and one-step RT-PCR.

CONCLUSION

This study opens the scene for studying the role of influenza virus's coinfection in disease severity and virus evolution. Further studies are required to better understand the clinical importance of viral coinfection.

Clinical characteristics of children and adults hospitalized for influenza virus infection

BACKGROUND/PURPOSE

Influenza infection has different clinical presentations and outcomes in children and adults, and bacterial coinfection is associated with significantly higher morbidity and mortality. This study compared the clinical features in children and adults hospitalized for influenza virus infection and the role of concomitant bacteremia.

METHODS

A retrospective observational cohort study was conducted by a review of medical records of all consecutive patients admitted for influenza infection between April 1, 2009 and February 28, 2011.

RESULTS

Of the 1203 patients, 76.2% were children, and ranged in age from 1 month to 99 years, with a mortality of 3.1% for adults; no children died. Pneumonia, acute respiratory distress syndrome, acute respiratory failure, septic shock, and cardiovascular complications were more common in adults. Bacteremia was more common in adults than in children (3.5% vs. 0.4%). C-reactive protein (CRP) > 4 mg/dL and a longer hospital stay occurred more often in children with bacteremia than in the group without bacteremia. In adults with bacteremia, acute respiratory failure, septic shock, and cardiovascular complications were more common, with a mortality of 50% versus 1.4% compared with those without bacteremia, and thrombocytopenia and increased CRP were independent risk factors. Using receiver operating characteristic analysis, CRP ≥ 14 mg/dL had a sensitivity of 90.0% and a specificity of 80.0%.

CONCLUSION

Influenza infection in adults is associated with increased risk of complications, bacteremia, and mortality compared with that in children. Bacteremia in adults with influenza is associated with increased complications and mortality; thrombocytopenia and elevated CRP levels could identify those at risk.

Clinical and radiological characteristics of 2009 H1N1 influenza associated pneumonia in young male adults

PURPOSE

Pneumonia was an important cause of death in 2009 H1N1 influenza pandemic (pH1N1). Clinical characteristics of pH1N1 have been described well, but discriminative characteristics suggesting pH1N1 infection in pneumonia patients are not evident today. We evaluated differences between clinical and radiologic characteristics for those associated and not associated with pH1N1 influenza during the pandemic period.

MATERIALS AND METHODS

We reviewed all patients with pneumonia who visited the Armed Forces Capital Hospital between July 2009 and February 2010. During this period, all pneumonia patients were tested for pH1N1 by reverse transcription-polymerase chain reaction (RT-PCR) using nasopharyngeal specimens.

RESULTS

In total, 98 patients with pneumonia were enrolled. Their median age was 20 years and all patients were males. Forty-nine (50%) of patients had pH1N1 infection and the others (50%) had negative results in pH1N1 RT-PCR. Patients with pH1N1 infection complained of dyspnea more commonly (83.3% vs. 29.0%; p<0.001), had higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores [5 (range, 0-12) vs. 3 (range, 0-11); p<0.01], fewer days of prehospital illness [2 (range, 0-10) vs. 4 (range, 0-14); p=0.001], and a higher chance of bilateral infiltrates on chest X-ray (CXR) (67.3% vs. 14.3%; p<0.001) and ground-glass opacity (GGO) lesions on computed tomography (CT; 48.9% vs. 22.0%; p<0.001) than patients without pH1N1 infection.

CONCLUSION

Dyspnea, bilateral infiltrates on CXR, and GGO on CT were dominant features in pH1N1-associated pneumonia. Understanding these characteristics can help selection of patients who require prompt antiviral therapy.

Occurrence of AH1N1 viral infection and clinical features in symptomatic patients who received medical care during the 2009 influenza pandemic in Central Mexico

Background

In 2009 a new influenza serotype (AH1N1) was identified in Mexico that spread rapidly generating worldwide alarm. San Luis Potosi (SLP) was the third state with more cases reported in that year. The clinical identification of this flu posed a challenge to medical staff. This study aimed at estimating the AH1N1 infection, hospitalization and mortality rates, and at identifying related clinical features in persons who received medical care during the influenza pandemic.

Methods

Retrospective study with persons with flu-like illness who received public or private medical care in SLP from 15.03.09 to 30.10.09. Physicians purposely recorded many clinical variables. Samples from pharyngeal exudate or bronchoalveolar lavage were taken to diagnose AH1N1 using real-time PCR. Clinical predictors were identified using multivariate logistic regression with infection as a dependent variable. Odds ratios (OR) with 95% confidence intervals (CI) were computed. Analyses were stratified by age group based on the distribution of positive cases.

Results

From the 6922 persons with flu symptoms 6158 had available laboratory results from which 44.9% turned out to be positive for AH1N1. From those, 5.8% were hospitalized and 0.7% died. Most positive cases were aged 5–14 years and, in this subgroup, older age was positively associated with A H1N1 infection (95% CI 1.05-1.1); conversely, in patients aged 15 years or more, older age was negatively associated with the infection (95% CI 0.97-0.98). Fever was related in those aged 15 years or more (95% CI 1.4-3.5), and headache (95% CI 1.2-2.2) only in the 0–14 years group. Clear rhinorrhea and cough were positively related in both groups (p < 0.05). Arthralgia, dyspnea and vaccination history were related to lesser risk in persons aged 15 years or more, just as dyspnea, purulent rhinorrhea and leukocytosis were in the 0–14 years group.

Conclusion

This study identified various signs and symptoms for the clinical diagnosis of AH1N1 influenza and revealed that some of them can be age-specific.

Relação entre morbidade hospitalar e cobertura vacinal contra Influenza A

OBJETIVO: Analisar o perfil dos indivíduos acometidos pelo vírus Influenza A (H1N1), e o impacto vacinal nos grupos prioritários à vacinação. MÉTODOS: Estudo ecológico, observacional, de caráter retrospectivo, com população de indivíduos residentes na cidade de Maringá-PR e submetidos à internação por Influenza A entre 2009 e 2010. RESULTADOS: No ano de 2009, ocorreram 614 internações decorrentes de infecção pelo vírus Influenza A em Maringá-PR. A disponibilização da vacina fez com que o número de acometidos diminuísse para 169 em 2010, ocorrendo impacto vacinal nos seguintes grupos populacionais: gestantes, portadores de doenças crônicas e adultos de 20 a 39 anos. CONCLUSÃO: Identificou-se a necessidade de estender a faixa etária de vacinação para crianças de 2 a 4 anos e preenchimento dos impressos de vacinação dos indivíduos e grupos vacinados com maior rigor.

Influenza A (H1N1)-associated pneumonia

OBJECTIVE

To describe the characteristics of patients with influenza A (H1N1)-associated pneumonia treated at two hospitals in the region of Liguria, Italy, as well as to describe their treatment and outcomes.

METHODS

This was a prospective observational study including all patients older than 16 years of age with a confirmed diagnosis of influenza A (H1N1) who were admitted to Villa Scassi Hospital, in the city of Genoa, Italy, or to the Sestri Levante General Hospital, in the city of Sestri Levante, Italy, between September of 2009 and January of 2010. The primary outcome measure was mortality within 60 days after diagnosis. Secondary outcome measures were the need for mechanical ventilation and the length of hospital stay.

RESULTS

Of the 40 patients with a confirmed diagnosis of influenza A (H1N1), 27 presented pneumonia during the study period. The mean age of the 27 patients was 42.8 ± 14.8 years, and the mean length of hospital stay was 11.6 ± 8.2 days. Of the 27 patients, 20 had respiratory failure, 4 underwent invasive mechanical ventilation, and 5 underwent noninvasive ventilation. One patient had comorbidities, developed multiple organ failure, and died.

CONCLUSIONS

During the influenza A (H1N1) pandemic, the associated mortality rate was lower in Italy than in other countries, and cases reported in the country typically had a milder course than did those reported elsewhere. Nevertheless, 9 of our cases (33%) rapidly evolved to respiratory failure, requiring mechanical ventilation.

Influenza and community-acquired pneumonia interactions: the impact of order and time of infection on population patterns

Discoveries made during the 1918 influenza A pandemic and reports of severe disease associated with coinfection during the 2009 hemagglutinin type 1 and neuraminidase type 1 (commonly known as H1N1 or swine flu) pandemic have renewed interest in the role of coinfection in disease pathogenesis. The authors assessed how various timings of coinfection with influenza virus and pneumonia-causing bacteria could affect the severity of illness at multiple levels of interaction, including the biologic and population levels. Animal studies most strongly support a single pathway of coinfection with influenza inoculation occurring approximately 7 days before inoculation with Streptococcus pneumoniae, but less-examined pathways of infection also may be important for human disease. The authors discussed the implications of each pathway for disease prevention and what they would expect to see at the population level if there were sufficient data available. Lastly, the authors identified crucial gaps in the study of timing of coinfection and proposed related research questions.

[Recommendations of the Infectious Diseases Work Group (GTEI) of the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC) and the Infections in Critically Ill Patients Study Group (GEIPC) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) for the diagnosis and treatment of influenza A/H1N1 in seriously ill adults admitted to the Intensive Care Unit]

The diagnosis of influenza A/H1N1 is mainly clinical, particularly during peak or seasonal flu outbreaks. A diagnostic test should be performed in all patients with fever and flu symptoms that require hospitalization. The respiratory sample (nasal or pharyngeal exudate or deeper sample in intubated patients) should be obtained as soon as possible, with the immediate start of empirical antiviral treatment. Molecular methods based on nucleic acid amplification techniques (RT-PCR) are the gold standard for the diagnosis of influenza A/H1N1. Immunochromatographic methods have low sensitivity; a negative result therefore does not rule out active infection. Classical culture is slow and has low sensitivity. Direct immunofluorescence offers a sensitivity of 90%, but requires a sample of high quality. Indirect methods for detecting antibodies are only of epidemiological interest. Patients with A/H1N1 flu may have relative leukopenia and elevated serum levels of LDH, CPK and CRP, but none of these variables are independently associated to the prognosis. However, plasma LDH> 1500 IU/L, and the presence of thrombocytopenia <150 x 10(9)/L, could define a patient population at risk of suffering serious complications. Antiviral administration (oseltamivir) should start early (<48 h from the onset of symptoms), with a dose of 75 mg every 12h, and with a duration of at least 7 days or until clinical improvement is observed. Early antiviral administration is associated to improved survival in critically ill patients. New antiviral drugs, especially those formulated for intravenous administration, may be the best choice in future epidemics. Patients with a high suspicion of influenza A/H1N1 infection must continue with antiviral treatment, regardless of the negative results of initial tests, unless an alternative diagnosis can be established or clinical criteria suggest a low probability of influenza. In patients with influenza A/H1N1 pneumonia, empirical antibiotic therapy should be provided due to the possibility of bacterial coinfection. A beta-lactam plus a macrolide should be administered as soon as possible. The microbiological findings and clinical or laboratory test variables may decide withdrawal or not of antibiotic treatment. Pneumococcal vaccination is recommended as a preventive measure in the population at risk of suffering severe complications. Although the use of moderate- or low-dose corticosteroids has been proposed for the treatment of influenza A/H1N1 pneumonia, the existing scientific evidence is not sufficient to recommend the use of corticosteroids in these patients. The treatment of acute respiratory distress syndrome in patients with influenza A/H1N1 must be based on the use of a protective ventilatory strategy (tidal volume <10 ml / kg and plateau pressure <35 mmHg) and positive end-expiratory pressure set to high patient lung mechanics, combined with the use of prone ventilation, muscle relaxation and recruitment maneuvers. Noninvasive mechanical ventilation cannot be considered a technique of choice in patients with acute respiratory distress syndrome, though it may be useful in experienced centers and in cases of respiratory failure associated with chronic obstructive pulmonary disease exacerbation or heart failure. Extracorporeal membrane oxygenation is a rescue technique in refractory acute respiratory distress syndrome due to influenza A/H1N1 infection. The scientific evidence is weak, however, and extracorporeal membrane oxygenation is not the technique of choice. Extracorporeal membrane oxygenation will be advisable if all other options have failed to improve oxygenation. The centralization of extracorporeal membrane oxygenation in referral hospitals is recommended. Clinical findings show 50-60% survival rates in patients treated with this technique. Cardiovascular complications of influenza A/H1N1 are common. Such problems may appear due to the deterioration of pre-existing cardiomyopathy, myocarditis, ischemic heart disease and right ventricular dysfunction. Early diagnosis and adequate monitoring allow the start of effective treatment, and in severe cases help decide the use of circulatory support systems. Influenza vaccination is recommended for all patients at risk. This indication in turn could be extended to all subjects over 6 months of age, unless contraindicated. Children should receive two doses (one per month). Immunocompromised patients and the population at risk should receive one dose and another dose annually. The frequency of adverse effects of the vaccine against A/H1N1 flu is similar to that of seasonal flu. Chemoprophylaxis must always be considered a supplement to vaccination, and is indicated in people at high risk of complications, as well in healthcare personnel who have been exposed.

Respiratory syncytial virus (RSV) community-acquired pneumonia (CAP) in a hospitalized adult with human immunodeficiency virus (HIV) mimicking influenza A and Pneumocystis (carinii) jiroveci pneumonia (PCP)

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infections in young children, the elderly, and immunocompromised hosts, but RSV is a rare cause of community-acquired pneumonia (CAP) in hospitalized adults with human immunodeficiency virus (HIV). In patients with HIV, CAP is most frequently attributable to the usual bacterial respiratory pathogens that cause CAP in immunocompetent hosts, eg, Streptococcuspneumoniae or Hemophilus influenzae. Adults with HIV are also predisposed to intracellular CAP pathogens, ie, Mycoplasmatuberculosis, Salmonella spp., Pneumocystis (carinii) jiroveci (PCP), cytomegalovirus, and Legionella spp. This year, co-circulating in the community during influenza season were strains of human seasonal influenza A (H3N2) and swine influenza A (H1N1). During the influenza season, in adults hospitalized with HIV, the diagnostic possibilities should include influenza-like illnesses, eg, human parainfluenza virus types 3 and 4, human metapneumovirus, and pertussis.

CASE REPORT

We present an adult with HIV, hospitalized for an influenza-like illness during influenza season. The differential diagnosis of CAP in this patient included influenza A and PCP.

CONCLUSION

We report on an adult patient with HIV with CAP that mimicked influenza and PCP, and was attributable to RSV.

Distinguishing characteristics between pandemic 2009-2010 influenza A (H1N1) and other viruses in patients hospitalized with respiratory illness

Background

Differences in clinical presentation and outcomes among patients infected with pandemic 2009 influenza A H1N1 (pH1N1) compared to other respiratory viruses have not been fully elucidated.

Methodology/Principal Findings

A retrospective study was performed of all hospitalized patients at the peak of the pH1N1 season in whom a single respiratory virus was detected by a molecular assay targeting 18 viruses/subtypes (RVP, Luminex xTAG). Fifty-two percent (615/1192) of patients from October, 2009 to December, 2009 had a single respiratory virus (291 pH1N1; 207 rhinovirus; 45 RSV A/B; 37 parainfluenza; 27 adenovirus; 6 coronavirus; and 2 metapneumovirus). No seasonal influenza A or B was detected. Individuals with pH1N1, compared to other viruses, were more likely to present with fever (92% & 70%), cough (92% & 86%), sore throat (32% & 16%), nausea (31% & 8%), vomiting (39% & 30%), abdominal pain (14% & 7%), and a lower white blood count (8,500/L & 13,600/L, all p-values<0.05). In patients with cough and gastrointestinal complaints, the presence of subjective fever/chills independently raised the likelihood of pH1N1 (OR 10). Fifty-five percent (336/615) of our cohort received antibacterial agents, 63% (385/615) received oseltamivir, and 41% (252/615) received steroids. The mortality rate of our cohort was 1% (7/615) and was higher in individuals with pH1N1 compared to other viruses (2.1% & 0.3%, respectively; p = 0.04).

Conclusions/Significance

During the peak pandemic 2009–2010 influenza season in Rhode Island, nearly half of patients admitted with influenza-like symptoms had respiratory viruses other than influenza A. A high proportion of patients were treated with antibiotics and pH1N1 infection had higher mortality compared to other respiratory viruses.

Pneumonia complicating pandemic (H1N1) 2009: risk factors, clinical features, and outcomes

We performed an observational analysis of a prospective cohort of adults hospitalized for pandemic (H1N1) 2009 at 13 Spanish hospitals, from June to November 2009, to determine the risk factors, clinical features, and outcomes of pneumonia. Of 585 patients requiring hospitalization, chest radiography was obtained in 542. A total of 234 (43.1%) patients had pneumonia, of whom 210 underwent bacterial microbiologic studies. Of these patients, 174 (82.8%) had primary viral pneumonia and 36 (17.2%) had concomitant/secondary bacterial pneumonia. Bilateral pneumonia occurred in 48.3% of patients. Streptococcus pneumoniae was the most frequent pathogen among patients with bacterial pneumonia (26 of 36 patients). None of them had received pneumococcal vaccine. Compared with patients without pneumonia, those with pneumonia more frequently had shock during hospitalization (9.8% vs. 1%; p < 0.001), required intensive care unit admission (22.6% vs. 5.8%; p < 0.001), underwent mechanical ventilation (17.9% vs. 3.2%; p < 0.001), and had longer length of hospital stay (median, 7 d vs. 5 d; p < 0.001). In-hospital mortality was higher in patients with pneumonia than in the others (5.2% vs. 0%; p < 0.001). Absence of comorbid conditions (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.32-3.24) was found to be an independent risk factor for pneumonia, whereas early (≤ 48 h) oseltamivir therapy (OR, 0.29; 95% CI, 0.19-0.46) was a protective factor. In conclusion, pneumonia is a frequent complication among adults hospitalized for pandemic (H1N1) 2009 and causes significant morbidity. Mortality in pandemic (H1N1) 2009 is low, but occurs mainly in patients with pneumonia. Early oseltamivir therapy is a protective factor for this complication.

Lung function and organ dysfunctions in 178 patients requiring mechanical ventilation during the 2009 influenza A (H1N1) pandemic

INTRODUCTION

Most cases of the 2009 influenza A (H1N1) infection are self-limited, but occasionally the disease evolves to a severe condition needing hospitalization. Here we describe the evolution of the respiratory compromise, ventilatory management and laboratory variables of patients with diffuse viral pneumonitis caused by pandemic 2009 influenza A (H1N1) admitted to the ICU.

METHOD

This was a multicenter, prospective inception cohort study including adult patients with acute respiratory failure requiring mechanical ventilation (MV) admitted to 20 ICUs in Argentina between June and September of 2009 during the influenza A (H1N1) pandemic. In a standard case-report form, we collected epidemiological characteristics, results of real-time reverse-transcriptase--polymerase-chain-reaction viral diagnostic tests, oxygenation variables, acid-base status, respiratory mechanics, ventilation management and laboratory tests. Variables were recorded on ICU admission and at days 3, 7 and 10.

RESULTS

During the study period 178 patients with diffuse viral pneumonitis requiring MV were admitted. They were 44 ± 15 years of age, with Acute Physiology And Chronic Health Evaluation II (APACHE II) scores of 18 ± 7, and most frequent comorbidities were obesity (26%), previous respiratory disease (24%) and immunosuppression (16%). Non-invasive ventilation (NIV) was applied in 49 (28%) patients on admission, but 94% were later intubated.Acute respiratory distress syndrome (ARDS) was present throughout the entire ICU stay in the whole group (mean PaO2/FIO2 170 ± 25). Tidal-volumes used were 7.8 to 8.1 ml/kg (ideal body weight), plateau pressures always remained < 30 cmH2O, without differences between survivors and non-survivors; and mean positive end-expiratory pressure (PEEP) levels used were between 8 to 12 cm H2O. Rescue therapies, like recruitment maneuvers (8 to 35%), prone positioning (12 to 24%) and tracheal gas insufflation (3%) were frequently applied. At all time points, pH, platelet count, lactate dehydrogenase assay (LDH) and Sequential Organ Failure Assessment (SOFA) differed significantly between survivors and non-survivors. Lack of recovery of platelet count and persistence of leukocytosis were characteristic of non-survivors. Mortality was high (46%); and length of MV was 10 (6 to 17) days.

CONCLUSIONS

These patients had severe, hypoxemic respiratory failure compatible with ARDS that persisted over time, frequently requiring rescue therapies to support oxygenation. NIV use is not warranted, given its high failure rate. Death and evolution to prolonged mechanical ventilation were common outcomes. Persistence of thrombocytopenia, acidosis and leukocytosis, and high LDH levels found in non-survivors during the course of the disease might be novel prognostic findings.

Influenza A presenting as viral encephalitis in an adult

In adults, influenza A may be accompanied by a variety of neurological findings. Influenza-associated encephalitis (IAE) is rare in adults, and usually follows influenza A after 2 days. In patients with influenza who later develop encephalitis, the diagnosis of IAE is relatively straightforward. We present a rare case of IAE in an adult who presented with viral encephalitis that was later attributed to antecedent influenza A.

Clinical, laboratory and radiologic characteristics of 2009 pandemic influenza A/H1N1 pneumonia: primary influenza pneumonia versus concomitant/secondary bacterial pneumonia

Please cite this paper as: Song et al. (2011). Clinical, laboratory and radiologic characteristics of 2009 pandemic influenza A/H1N1 pneumonia: primary influenza pneumonia versus concomitant/secondary bacterial pneumonia. Influenza and Other Respiratory Viruses 5(6), e535–e543.

Background  Although influenza virus usually involves the upper respiratory tract, pneumonia was seen more frequently with the 2009 pandemic influenza A/H1N1 than with seasonal influenza.

Methods  From September 1, 2009, to January 31, 2010, a specialized clinic for patients (aged ≥15 years) with ILI was operated in Korea University Guro Hospital. RT‐PCR assay was performed to diagnose 2009 pandemic influenza A/H1N1. A retrospective case–case–control study was performed to determine the predictive factors for influenza pneumonia and to discriminate concomitant/secondary bacterial pneumonia from primary influenza pneumonia during the 2009–2010 pandemic.

Results  During the study period, the proportions of fatal cases and pneumonia development were 0·12% and 1·59%, respectively. Patients with pneumonic influenza were less likely to have nasal symptoms and extra‐pulmonary symptoms (myalgia, headache, and diarrhea) compared to patients with non‐pneumonic influenza. Crackle was audible in just about half of the patients with pneumonic influenza (38·5% of patients with primary influenza pneumonia and 53·3% of patients with concomitant/secondary bacterial pneumonia). Procalcitonin, C‐reactive protein (CRP), and lactate dehydrogenase were markedly increased in patients with influenza pneumonia. Furthermore, procalcitonin (cutoff value 0·35 ng/ml, sensitivity 81·8%, and specificity 66·7%) and CRP (cutoff value 86·5 mg/IU, sensitivity 81·8%, and specificity 59·3%) were discriminative between patients with concomitant/secondary bacterial pneumonia and patients with primary influenza pneumonia.

Conclusions  Considering the subtle manifestations of 2009 pandemic influenza A/H1N1 pneumonia in the early stage, high clinical suspicion is required to detect this condition. Both procalcitonin and CRP would be helpful to differentiate primary influenza pneumonia from concomitant/secondary bacterial pneumonia.

Fulminant fatal swine influenza (H1N1): Myocarditis, myocardial infarction, or severe influenza pneumonia?

The swine influenza (H1N1) pandemic began in Mexico and rapidly spread worldwide. As is the case with pandemic influenza A, the majority of early deaths have been in young healthy adults. The complications of pandemic H1N1 have been reported from several centers. Noteworthy has been the relative rarity of bacterial coinfection in bacterial pneumonia in hospitalized adults with H1N1 pneumonia. Simultaneous bacterial community-acquired pneumonia due to methicillin-sensitive Staphylococcus aureus or community-acquired methicillin resistant S. aureus and subsequent bacterial community-acquired pneumonia due to S. pneumoniae or Haemophilus influenzae have been reportedly rare (0.4%-4% of well-documented cases). Cardiac complications of H1N1 infection have been uncommon. Young healthy adults without a cardiac history who have H1N1 and chest pain usually have either acute myocardial infarction or acute myocarditis. Cardiac symptomatology with H1N1 often overshadows pulmonary manifestations, that is, influenza pneumonia. With H1N1 pneumonia, clinicians should be alert for otherwise unexplained tachycardia or chest pain that may represent acute myocardial infarction or myocarditis. We present a case of rapidly fatal H1N1 in a young adult treated with oseltamivir and peramivir. He was initially tachycardic, thought to represent myocarditis. He subsequently became hypotensive and expired. At autopsy there was cardiomegaly present but there were no signs of acute myocardial infarction or myocarditis. Pathologically, he died of severe H1N1 pneumonia and not bacterial pneumonia.

Rapid clinical diagnosis of Legionnaires' disease during the "herald wave" of the swine influenza (H1N1) pandemic: the Legionnaires' disease triad

BACKGROUND

In adults hospitalized with atypical community-acquired pneumonia (CAP), Legionnaires' disease is not uncommon. Legionnaire's disease can be differentiated from typical CAPs and from other atypical CAPs based on its characteristic pattern of extrapulmonary organ involvement. The first clinically useful diagnostic weighted point score system for the clinical diagnosis of Legionnaires' disease was developed by the Infectious Disease Division at Winthrop-University Hospital in the 1980s. It has proven to be diagnostically accurate and useful for more than two decades, but was time-consuming. Because Legionella spp. diagnostic tests are time-dependent and problematic, a need was perceived for a rapid, simple way to render a clinical, syndromic diagnosis of Legionnaires' disease pending Legionella test results. During the "herald wave" of the swine influenza (H1N1) pandemic in the New York area, our hospital, like others, was inundated with patients who presented to the Emergency Department with influenza-like illnesses (ILIs) for H1N1 testing/evaluation. Most patients with ILIs did not have swine influenza. Hospitalized patients with ILIs who tested positive with rapid influenza diagnostic tests (RIDTs) were placed on influenza precautions and treated with oseltamivir. Unfortunately, approximately 30% of adult patients admitted with an ILI had negative RIDTs. Because the definitive laboratory diagnosis of H1N1 pneumonia by reverse transcription-polymerase chain reaction(RT-PCR), testing was restricted by health departments, resulted in clinical and infection control dilemmas in determining which RIDT-negative patients did, in fact, have H1N1 pneumonia.

OBJECTIVE

Accordingly, a diagnostic weighted point score system was developed for H1N1 pneumonia patients, based on RT-PCR positivity by the Infectious Disease Division at Winthrop-University Hospital. This diagnostic point score system for hospitalized adults with negative RIDTs was time-consuming. As the pandemic progressed, a simplified diagnostic swine influenza (H1N1) triad was developed for the rapid clinical diagnosis of probable H1N1 pneumonia, which also differentiated it from its mimics as well as from bacterial pneumonia, eg, Legionnaires' disease. During the "herald wave" of the H1N1 pandemic, we noticed an unexplained increase in Legionnaires' disease CAPs. Because clinical resources were stressed to the maximum during the pandemic, it was critically important to rapidly identify patients rapidly with Legionnaire's disease who did not require influenza precautions or oseltamivir, but who did require anti-Legionella antimicrobial therapy.

METHODS

Based on the Winthrop-University Hospital Infectious Disease Division's diagnostic weighted point score system for Legionnaires' disease (modified), key indicators were identified and became the basis for the diagnostic Legionnaires' disease triad. The diagnostic Legionnaires' disease triad was used to make a clinical diagnosis of Legionnaires' disease until the results of Legionella diagnostic tests were reported. The diagnostic Legionnaires' disease triad diagnosed Legionnaires' disease in hospitalized adults with CAPs with extrapulmonary findings (atypical CAP) and relative bradycardia, accompanied by any three (ie, a triad) of the following: otherwise unexplained relative lymphopenia, early/mildly elevated serum transaminases (SGOT/SGPT), highly increased ferritin levels (> or =2 x n), or hypophosphatemia. The diagnostic Legionnaires' disease triad provides clinicians with a rapid way to clinically diagnose Legionnaires' disease, pending Legionella test results.

RESULTS

The accuracy of the diagnostic Legionnaires' disease triad was confirmed in our 9 cases of Legionnaires' disease by subsequent Legionella diagnostic testing.

CONCLUSIONS

The diagnostic Legionnaires' disease triad is particularly useful in situations where a rapid clinical syndromic diagnosis is needed, ie, during an H1N1 pandemic.

Systemic lupus erythematosus (SLE) pneumonitis mimicking swine influenza pneumonia during the swine influenza (H1N1) pandemic

BACKGROUND

We present a young woman with a negative medical history who presented with acute systemic lupus erythematosus (SLE) pneumonitis mimicking swine influenza (H1N1) pneumonia. Because this case occurred during the H1N1 pandemic, the initial diagnostic impression was of H1N1 pneumonia.

METHODS

Although her clinical and laboratory findings were consistent with the diagnosis of H1N1 pneumonia, e.g., fever, sore throat, dry cough, arthralgias, myalgias, thrombocytopenia, relative lymphopenia, and elevated serum transaminases, some findings suggested an alternate diagnosis, e.g., leukopenia, a highly elevated erythrocyte sedimentation rate, highly elevated serum ferritin levels, elevated antinuclear antibody (ANA) levels, and double-stranded (DS) DNA titers. Her chest x-ray showed an accentuation of basilar lung markings, with a small pleural effusion similar to the chest x-ray findings of early H1N1 pneumonia. Initially, her headaches were thought to be related to central nervous system manifestations of H1N1.

RESULTS

After laboratory test results demonstrated elevated ANA and anti-DS DNA titers, she was diagnosed with acute SLE pneumonitis. The take-home lesson for clinicians is that other infectious diseases, e.g., human parainfluenza virus or Legionnaires' disease, can mimic H1N1 pneumonia during an influenza pandemic. Excluding asthma, congestive heart failure, exacerbations of acute bronchitis, chronic obstructive pulmonary disorder, and pulmonary interstitial disease, noninfectious mimics of H1N1 are extremely rare.

CONCLUSION

To the best of our knowledge, this is the first reported case of de novo SLE pneumonitis mimicking H1N1 pneumonia during the swine influenza pandemic.

Pneumonia in patients with novel influenza A (H1N1) virus in Southeastern Turkey

The objective of this study was to describe the clinical characteristics and the radiological and laboratory findings of the hospitalised patients who had novel, laboratory-confirmed, swine-origin influenza A virus (S-OIV) infection with pneumonia. Between October and December 2009, 56 patients hospitalised for pneumonia who were tested for S-OIV infection were retrospectively evaluated. Thirty-three patients had positive S-OIV infections. In addition, 23 of the 56 patients who had negative test results for S-OIV infection were compared with the positive group. The mortality rate amongst the patients with S-OIV infection was 24.2%. Of the 33 patients, 42.4% had at least one underlying medical condition and 4 (12%) patients were pregnant or postpartum. Fourteen patients (42.4%) with S-OIV infection were followed up in an intensive care unit. The most common symptom was dyspnea. The mean peak body temperature during hospital stay (39.42 ± 0.70) was higher in this group than in the negative group (38.51 ± 1.05) (p = 0.001). Thrombocytopenia, increased creatine kinase and elevated lactate dehydrogenase levels were statistically significant. Bilateral infiltration was more common in the patients with S-OIV infection. Although some laboratory, radiological and clinical data show a significant difference between the patients with S-OIV pneumonia and the negative group, each patient presenting with signs of pneumonia during pandemia should be tested for Influenza A.

Human parainfluenza virus type 3 (HPIV 3) community-acquired pneumonia (CAP) mimicking pertussis in an adult: the diagnostic importance of hoarseness and monocytosis

BACKGROUND

There are relatively few causes of acute community-acquired pneumonias (CAPs) in adults associated with prolonged cough. In adults the most common acute CAPs with a prominent and persistent nonproductive cough are due to Mycoplasma pneumoniae, Chlamydophilia (Chlamydia) pneumoniae, or Bordetella pertussis (pertussis). Pertussis is an underrecognized and underappreciated cause of CAP in adults. Different from classic pertussis in children, pertussis in adults presents with prolonged dry cough, that is, the "100-day cough." In pertussis, the characteristic nonspecific laboratory findings are leukocytosis and relative lymphocytosis. Dry cough accompanied by hoarseness with CAP in an adult should suggest C. pneumoniae or a respiratory virus (eg, influenza, parainfluenza, respiratory syncytial virus).

METHODS

We present the case of a young woman who presented with a prominent and persistent pertussis-like cough with hoarseness. She had no leukocytosis or relative lymphopenia, which argued against the diagnosis of pertussis. Notably, she had persistent monocytosis. Her protracted pertussis-like cough that persisted during her hospitalization was so impressive that the diagnostic impression was pertussis. Direct fluorescent antibody (FA) and throat cultures were negative for pertussis. Furthermore, her hoarseness suggested the possibility of C. pneumoniae, but her C. pneumoniae immunoglobulin-M titer was negative.

RESULTS

Because C. pneumoniae was ruled out, her hoarseness suggested a respiratory viral cause. A respiratory FA viral panel and viral throat cultures were obtained. The respiratory FA viral panel was negative for influenza A/B, respiratory syncytial virus, metapneumovirus, adenovirus, cytomegalovirus, and parainfluenza viruses. However, her viral throat cultures grew parainfluenza virus type 3 (HPIV 3), confirming the diagnosis.

CONCLUSION

To the best of our knowledge, this is the first case of HPIV 3 CAP presenting with a prominent and persistent pertussoid cough in an adult mimicking pertussis with hoarseness and monocytosis.

Gene expression profiles comparison between 2009 pandemic and seasonal H1N1 influenza viruses in A549 cells

OBJECTIVE

To perform gene expression profiles comparison so that to identify and understand the potential differences in pathogenesis between the pandemic and seasonal A (H1N1) influenza viruses.

METHODS

A549 cells were infected with A/California/07/09 (H1N1) and A/GuangdongBaoan/51/08 (H1N1) respectively at the same MOI of 2 and collected at 2, 4, 8, and 24 h post infection (p.i.). Gene expression profiles of A549 cells were obtained using the 22 K Human Genome Oligo Array, and differentially expressed genes were analyzed at selected time points.

RESULTS

Microarrays results indicated that both of the viruses suppressed host immune response related pathways including cytokine production while pandemic H1N1 virus displayed weaker suppression of host immune response than seasonal H1N1 virus. Observation on similar anti-apoptotic events such as activation of apoptosis inhibitor and down-regulation of key genes of apoptosis pathways in both infections showed that activities of promoting apoptosis were different in later stage of infection.

CONCLUSIONS

The immuno-suppression and anti-apoptosis events of pandemic H1N1 virus were similar to those seen by seasonal H1N1 virus. The pandemic H1N1 virus had an ability to inhibit biological pathways associated with cytokine responses, NK activation and macrophage recognition.

Swine influenza (H1N1) and acute appendicitis

BACKGROUND

During the swine influenza (H1N1) pandemic that began in 2009, many hospitalized adults had gastrointestinal symptoms. The most common symptoms associated with swine influenza (H1N1) were nausea, vomiting, or diarrhea. In the experience of the authors, swine influenza was not complicated by abdominal pain. There are a wide variety of infectious and non-infectious disorders that may present with a pain in the right lower quadrant, mimicking appendicitis, ie, pseudoappendicitis. Influenza predisposes to some types of bacterial infection, eg, influenza pneumonia may be complicated by simultaneous Staphylococcus aureus community-acquired pneumonia or subsequent community-acquired pneumonia due to Haemophilus influenzae or Streptococcus pneumoniae. It remains unclear if there is direct involvement of the appendix, ie, pseudoappendicitis as occurs with measles or if influenza itself somehow predisposes to increased frequency/severity of bacterial appendicitis. German clinicians first noted an increased incidence of acute appendicitis in children/young adults with influenza. The American and British cases of influenza and acute appendicitis compared to age-matched controls with more severe and of delayed onset/complicated by appendicial perforation/abscess. These reports noted an increased incidence/severity of acute appendicitis during influenza.

METHODS AND RESULTS

A 15-year-old girl presented to the hospital with an influenza-like illness and right lower quadrant abdominal pain. Acute appendicitis was diagnosed by a computed tomography scan and the patient underwent emergency appendectomy. Subsequently, it was noted that she did not have leukocytosis and, in fact, had borderline leukopenia. Her differential white blood cell count also revealed relative lymphopenia. Neither leukopenia nor relative lymphopenia are features of acute bacterial appendicitis. These two findings in the setting of an influenza-like illness indicate the underlying presence of influenza. Post-operatively, respiratory secretion samples were sent for swine influenza (H1N1) testing. Both her respiratory florescent antibody (FA viral panel) was positive for influenza A, as was her RT-PCR for swine influenza (H1N1). The authors believe that this is the first case of swine influenza (H1N1) and acute bacterial appendicitis. Direct involvement of the appendix by swine influenza (H1N1) virus could not be demonstrated.

CONCLUSIONS

The authors conclude that during the swine influenza (H1N1) pandemic clinicians should be alert to the possibility of an increased incidence/severity of acute bacterial appendicitis in patients with swine influenza (H1N1) infection.

Legionnaires' disease mimicking swine influenza (H1N1) pneumonia during the "herald wave" of the pandemic

BACKGROUND

New York area hospitals were hit hard by the swine influenza (H1N1) pandemic in spring and summer 2009. During a pandemic, the initial cases may be difficult to recognize, but subsequent clinical diagnoses were relatively straightforward, given the high volume of cases and their typical clinical presentation. Swine influenza pneumonia presents as an influenza-like illness (ILI) with dry cough, fever >102 degrees F and myalgias. A variety of other viral pneumonias, eg, cytomegalovirus, human parainfluenza virus 3 (HPIV 3), and adenovirus, as well as bacterial community-acquired pneumonias (CAPs) that may present with some of the clinical and laboratory features of H1N1 pneumonia. Most adults admitted to hospitals with ILIs during the pandemic had, in fact, definite or probable H1N1 pneumonia. The Infectious Disease Division at Winthrop-University Hospital developed a diagnostic weighted point score to identify probable H1N1 cases in hospitalized adults with rapid negative influenza diagnostic tests (RIDTs).

METHODS

We present a case of an elderly male who presented with an ILI and negative RIDTs during the H1N1 pandemic. He was admitted with a diagnosis of possible H1N1, and placed on influenza precautions and oseltamivir. Although the patient had features consistent with H1N1 pneumonia, Legionnaires' disease was included in the differential diagnosis because of his elevated serum ferritin levels. A Legionella urinary antigen test was positive for Legionella pneumophila (serogroups 01-06).

RESULTS

The peak seasonal incidence of sporadic Legionnaires' disease occurs in the summer and fall. Even in the midst of a pandemic, clinicians should be on the alert for other infectious diseases that may mimic H1N1 pneumonia. In our experience, the best way to differentiate H1N1 from ILIs or other bacterial CAPs is through the Winthrop-University Hospital Infectious Disease Division's diagnostic weighted point score system for H1N1 pneumonia or its rapid simplified version, ie, the diagnostic swine influenza triad. Legionnaires' disease is the atypical CAP pathogen most likely to mimic H1N1 pneumonia.

CONCLUSIONS

Based on this and other nine cases at our institution during the "herald wave" of pandemic, we conclude that Legionnaires' disease may mimic swine influenza (H1N1) pneumonia.

What Every Cardiologist Should Know about H1N1?

The world is witnessing ever fastest growing pandemic with high morbidity and mortality that excessive volume of airline travels spread influenza infection; so physicians with various specialties should know and consider the impact of current pandemic on their daily practice. Among influenza A viruses that infect humans, an influenza A virus emerged that had shifted to H1N1. Primarily, the results of pandemic of H1N1 were in younger humans without preexisting immunity. Attack rates of swine influenza are relatively high, but mortality is relatively low and mortality rate is highest in the very young, the very old, and the immunosuppressed. In this new pandemic, there is not more evidence of the interface of H1N1 with chronic diseases; however, we expect that the Swine flu such as the previous influenza pandemics can change the course of many chronic diseases.In this review, we want to show the impacts of swine flu on cardiovascular system and disease. We will also discuss the importance of vaccination in chronic cardiovascular disease.