Relationship among Dietary Intake of Vitamin E, Lipid Peroxidation Markers, and C-Reactive Protein in Flu-Like Patients Diagnosed with COVID-19.

Objective: This research aimed to assess the intake of vitamin E and its relationship with lipid peroxidation markers and C-reactive protein levels in patients with flu symptoms and COVID-19 diagnosis. Methods: A cross-sectional study with 121 patients of both sexes assisted at two basic health units in the city of Teresina, Piauí, with COVID-19 diagnosis confirmed through real-time reverse transcription polymerase chain reaction, was performed between the 3rd and 7th days of flu symptoms. The global nutritional status and the measurement of waist circumference were assessed according to the World Health Organization recommendations. The dietary energy intake, macronutrients, and vitamin E consumption were assessed through the 24 hr food recall method. The malondialdehyde plasmatic concentration (MDA) was measured through the method of thiobarbituric acid-reactive substances. Myeloperoxidase (MPO) was assessed through the oxidation speed of the o-dianisidine substrate in the presence of hydrogen peroxide. C-reactive protein (CRP) levels were measured by a high-sensitivity immunoturbidimetry method. Results: The most common symptoms reported by the participants were sore throat, fever, and cough. Regarding the global nutritional status evaluation, the majority of the sample had overweight. The dietary intake of vitamin E was 100% inadequate and presented a mild correlation (r = 0.197) with MDA, a redox status marker. No correlation was observed among MPO, CRP, and the dietary intake of vitamin E. Conclusion: The dietary intake of vitamin E was related to MDA as the marker of redox status.

Clinical and Immunological Factors That Distinguish COVID-19 From Pandemic Influenza A(H1N1).

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), is a global health threat with the potential to cause severe disease manifestations in the lungs. Although COVID-19 has been extensively characterized clinically, the factors distinguishing SARS-CoV-2 from other respiratory viruses are unknown. Here, we compared the clinical, histopathological, and immunological characteristics of patients with COVID-19 and pandemic influenza A(H1N1). We observed a higher frequency of respiratory symptoms, increased tissue injury markers, and a histological pattern of alveolar pneumonia in pandemic influenza A(H1N1) patients. Conversely, dry cough, gastrointestinal symptoms and interstitial lung pathology were observed in COVID-19 cases. Pandemic influenza A(H1N1) was characterized by higher levels of IL-1RA, TNF-α, CCL3, G-CSF, APRIL, sTNF-R1, sTNF-R2, sCD30, and sCD163. Meanwhile, COVID-19 displayed an immune profile distinguished by increased Th1 (IL-12, IFN-γ) and Th2 (IL-4, IL-5, IL-10, IL-13) cytokine levels, along with IL-1ß, IL-6, CCL11, VEGF, TWEAK, TSLP, MMP-1, and MMP-3. Our data suggest that SARS-CoV-2 induces a dysbalanced polyfunctional inflammatory response that is different from the immune response against pandemic influenza A(H1N1). Furthermore, we demonstrated the diagnostic potential of some clinical and immune factors to differentiate both diseases. These findings might be relevant for the ongoing and future influenza seasons in the Northern Hemisphere, which are historically unique due to their convergence with the COVID-19 pandemic.

Cortisol and perceived stress are associated with cytokines levels in patients infected with influenza B virus.

Influenza B virus (IBV) causes respiratory infectious disease. Cytokines are important immune mediators during infectious diseases. Cortisol and stress have been related to respiratory infection susceptibility and cytokine regulation. Little is known about systemic cytokines, cortisol, and perceived stress in the early stages of IBV infection. We researched the systemic cytokines and cortisol, as well as the perceived stress and blood cell count in patients infected with IBV. The diagnosis was established using the Luminex xTAG RVP kit and confirmed with qRT-PCR for IBV viral load. The perceived stress was evaluated using the perceived stress scale (PSS-10). Twenty-five plasma cytokines were determined using multiplex immunoassay and cortisol by ELISA. The leukocyte differential count was measured with a standard laboratory protocol. Th1, Th17, and IL-10 cytokines were higher in IBV infected patients (P < 0.05). Leukocytes and neutrophil count negatively correlated with viral load (P < 0.05). Perceived stress had a negative effect on monocyte and systemic cytokines in IBV infected patients (P < 0.05). Cortisol was higher in patients infected with IBV and correlated positively with CCL20 (P < 0.05). Cortisol showed a positive effect on most of the systemic cytokines (P < 0.05). In conclusion, a cytokine pattern was found in IBV infected patients, as well as the possible role of leukocyte counts in the control of IBV. Our results suggest the importance of cortisol and perceived stress on systemic cytokines in patients infected with IBV, but more studies are needed to understand their role in cytokine production in respiratory infectious disease.

O que o passado tem a nos ensinar sobre a Influenza? / What does the past have to teach us about influenza? / ¿Qué puede enseñarnos el pasado sobre la Influenza?

Objetivo: apresentar narrativa dos acontecimentos históricos sobre a epidemia de Influenza e suas interfaces com a saúde pública e enfermagem. Conteúdo: destaca-se a cultura, e os modos de ver a história ao longo dos anos para compreensão do comportamento epidemiológico da Influenza no Brasil, suas epidemias e o que se apreendeu e construiu após 100 anos cuidando e estudando sobre este agravo durante as epidemias que ocorreram no Brasil. Conclusão: entender que a imunização é a estratégia mais eficaz no controle de doenças transmissíveis e, no caso da Influenza, como imunobiológico potente, deve ser o legado apreendido das grandes epidemias deste agravo, mas também, a vigilância e educação em saúde das populações para tal, principalmente com foco nos movimentos antivacinas.

Objective: to present a narrative of historical events regarding the influenza epidemic and its interfaces with public health and nursing. Content: the study highlights culture and ways of seeing history over the years, in order to understand the epidemiological behavior of influenza in Brazil, its epidemics, and what has been learned and built after 100 years' caring for and studying this condition during epidemics that occurred in Brazil. Conclusion: immunization is the most effective strategy for controlling communicable diseases and, in the case of Influenza, is a powerful immunobiological resource. This should be the legacy learned from the major epidemics of this disease, as well as health surveillance and education of the public for the same purpose, with a special focus on anti-vaccine movements.

Objetivo: presentar narrativa de los sucesos históricos sobre la epidemia de Influenza y sus interfaces con la salud pública y la enfermería. Contenido: se destacan la cultura y los modos de ver la historia a lo largo de los años, para comprender el comportamiento epidemiológico de la Influenza en Brasil, sus epidemias y lo que se aprendió y construyó después de 100 años cuidando y estudiando sobre este agravio durante las epidemias que ocurrieron en Brasil. Conclusión: entender que la inmunización es la estrategia más eficaz en el control de enfermedades transmisibles y, en el caso de la Influenza, como inmunobiológico potente, ese debe ser el legado comprendido de las grandes epidemias. Asimismo, se debe llevar en cuenta la vigilancia y la educación en salud de las poblaciones, principalmente con foco en los movimientos antivacunas.

H1N1: perfil clínico-epidemiológico de pacientes atendidos em um hospital / H1N1: clinical and epidemiological profile of patients treated in a hospital

Objetivo: Avaliar casos de suspeita de gripe H1N1, bem como comparar aspectos epidemiológicos e clínicos dos pacientes com gripe H1N1 confirmada em relação àqueles não confirmados; analisar os critérios de gravidade clínica com relação à confirmação (ou não) da gripe H1N1 e seu desfecho (mortalidade); e criar um banco de dados para fins de comparação com a literatura nacional e mundial. Métodos: Estudo retrospectivo de coorte transversal realizado no período sazonal (outono e inverno) no ano de 2016. Foram analisados os prontuários, acessíveis e completos, de pacientes com suspeita clínica de H1N1, além daqueles com resultados definidos na sorologia. A partir dos dados coletados, foi elaborada tabela de análise epidemiológica, com informações clínicas, laboratoriais e sorológicas. Resultados: Destacam-se a média das faixas etárias mais acometidas de 48 anos, além dos sintomas mais comuns que foram dispneia, tosse e mialgia; as comorbidades foram hipertensão arterial sistêmica, cardiopatias, diabetes e doença pulmonar obstrutiva crônica. Conclusão: Este trabalho contribuiu com a caracterização do perfil epidemiológico regional e auxiliou na definição de indicadores de diagnóstico e gravidade, além de agregar à literatura conteúdos de caráter relevante. Este estudo está registrado como CAAE 58664016.2.0000.5515 na Plataforma Brasil. (AU)

Objective: To evaluate cases of suspected H1N1 flu, as well as to compare epidemiological and clinical aspects of patients with confirmed H1N1 influenza to those who were not confirmed; to analyze the criteria of clinical severity regarding the confirmation (or not) of H1N1 influenza, and its outcome (mortality); and to create a database to be compared with the national and world literature. Methods: This is a cross-sectional retrospective cohort study, carried out in the seasonal period ( fall/winter) of 2016. Accessible and complete medical records of patients with clinical suspicion of H1N1 were analyzed along with those with defined serology results. Based on the collected data, a table of epidemiological analysis was elaborated with clinical, laboratory and serological information. Results: The mean age of the most affected age groups was 48 years; the most common symptoms were dyspnea, cough and myalgia; and the comorbidities were systemic arterial hypertension, cardiopathies, diabetes, and chronic obstructive pulmonary disease. Conclusion: This work contributed to the characterization of the regional epidemiological profile, and helped in the definition of indicators of diagnosis and severity, besides adding relevant content to the literature. This study is registered as CAAE 58664016.2.0000.5515 at Plataforma Brasil. (AU)

Serological study of influenza viruses in veterinarians working with swine in Mexico.

Humans and swine are both affected by influenza viruses, and swine are considered a potential source of new influenza viruses. Transmission of influenza viruses across species is well documented. The aim of this study was to evaluate the seroprevalence of different influenza virus subtypes in veterinarians working for the Mexican swine industry, using a hemagglutination inhibition test. All sera tested were collected in July 2011. The data were analysed using a generalized linear model and a linear model to study the possible association of seroprevalence with the age of the veterinarian, vaccination status, and biosecurity level of the farm where they work. The observed seroprevalence was 12.3%, 76.5%, 46.9%, and 11.1% for the human subtypes of pandemic influenza virus (pH1N1), seasonal human influenza virus (hH1N1), the swine subtypes of classical swine influenza virus (swH1N1), and triple-reassortant swine influenza virus (swH3N2), respectively. Statistical analysis indicated that age was associated with hH1N1 seroprevalence (P < 0.05). Similarly, age and vaccination were associated with pH1N1 seroprevalence (P < 0.05). On the other hand, none of the studied factors were associated with swH1N1 and swH3N2 seroprevalence. All of the pH1N1-positive sera were from vaccinated veterinarians, whereas all of those not vaccinated tested negative for this subtype. Our findings suggest that, between the onset of the 2009 pandemic and July 2011, the Mexican veterinarians working in the swine industry did not have immunity to the pH1N1 virus; hence, they would have been at risk for infection with this virus if this subtype had been circulating in swine in Mexico prior to 2011.

Circulating levels of miR-150 are associated with poorer outcomes of A/H1N1 infection.

BACKGROUND: Overproduction of pro-inflammatory cytokines and chemokines is frequently associated with severe clinical manifestations in patients infected with influenza A/H1N1 virus. Micro-RNAs (miRNAs) are highly conserved small non-coding RNA molecules that post-transcriptionally regulate gene expression and are potential biomarkers and therapeutic targets in different inflammatory conditions. METHODS: We studied the circulating and miRNA profiles in critically ill A/H1N1 patients, A/H1N1 patients with milder disease, asymptomatic housemates and healthy controls. Cytokine, chemokine and growth factors that were potential targets of differentially expressed miRNAs were assessed. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment and interactome analysis of these miRNAs were also performed. RESULTS: Critically ill patients exhibited a significant over-expression of circulating miR-150 (p<0.005) when compared to patients with milder disease. miR-29c, miR-145 and miR-22 were differentially expressed in patients with severe A/H1N1 disease whereas miR-210, miR-126 and miR-222 were downregulated in individuals exposed to the A/H1N1 virus. Significant correlations (p<0.05) between circulating levels of miR-150 with IL-1ra, IL-2, IL-6, CXCL8, IFN-γ, CXCL10 and G-CSF were detected, particularly in critically ill patients. CONCLUSION: The up-regulation of miR-150 is associated with poorer outcomes of A/H1N1 infection. The differential expression of miRNAs related with immune processes in severe A/H1N1 disease supports the potential role of these miRNAs as biomarkers of disease progression.

Serum surfactant protein D (SP-D) is a prognostic marker of poor outcome in patients with A/H1N1 virus infection.

INTRODUCTION: Surfactant protein D (SP-D) plays an important role in the innate responses against pathogens and its production is altered in lung disorders. METHODS: We studied the circulating levels of SP-D in 37 patients with acute respiratory distress syndrome due to the A/H1N1 virus infection and in 40 healthy controls. Cox logistic regression models were constructed to explore the association of SP-D levels and risk of death. RESULTS: Mortality rate after a 28-day was 32.42 %. Significant higher levels of SP-D were detected in A/H1N1 patients with fatal outcome (p < 0.05). After adjusting for confounding variables, levels of SP-D ≥250 ng/mL were associated with increased the risk of death (HR = 8.27, 95 % CI 1.1-64.1, p = 0.043). CONCLUSIONS: Our results revealed that higher circulating levels of SP-D are associated with higher mortality risk in critically ill A/H1N1 patients. SP-D might be a predictive factor of poor outcomes in viral pneumonia.

Production of interferon α and ß, pro-inflammatory cytokines and the expression of suppressor of cytokine signaling (SOCS) in obese subjects infected with influenza A/H1N1.

BACKGROUND & AIMS: Obesity was recognized as an independent risk factor for morbidity and mortality during last influenza A/H1N1 pandemic. Mechanisms involved in the high mortality risk from obesity during influenza A virus include reduced type I interferon production and delayed pro-inflammatory response, which lead to a higher rate of morbidity and mortality in murine models. In this study, we evaluated the production of type I interferons, pro-inflammatory and anti-inflammatory cytokines in peripheral blood mononuclear cells (PBMCs) from obese and lean subjects with and without confirmed infection of influenza A/H1N1. The expression levels of the suppressor of cytokine signaling-1 (SOCS1), SOCS3 and nuclear factor-kB were also evaluated. METHODS: Cytokines were measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and/or by ELISA in PBMCs stimulated with toll like receptor-3 (TLR-3) and TLR-7 ligands. The mRNA expression of SOCS1 and SOCS3 were evaluated by qRT-PCR. RESULTS: The obese volunteers infected with influenza A/H1N1 showed a diminished ability to produce type I interferon in response to TLR-3 ligand. Interestingly, the pro-inflammatory response was also affected in TLR-3 stimulated PBMCs. Obese influenza-free volunteers showed an increased basal expression of SOCS3, but not SOCS1. During influenza infection, SOCS1 and SOCS3 expression was higher in the lean infected volunteers in contrast to those who were obese infected. CONCLUSIONS: These data suggest that obesity is related to TLR-3 impairment and explain, at least in part, the inadequate immune response of obese individuals during infection with influenza A/H1N1 virus.

Potentially-toxic and essential elements profile of AH1N1 patients in Mexico City.

During spring of 2009, a new influenza virus AH1N1 spread in the world causing acute respiratory illness and death, resulting in the first influenza pandemic since 1968. Blood levels of potentially-toxic and essential elements of 40 pneumonia and confirmed AH1N1 were evaluated against two different groups of controls, both not infected with the pandemic strain. Significant concentrations of potentially-toxic elements (lead, mercury, cadmium, chromium, arsenic) along with deficiency of selenium or increased Zn/Cu ratios characterized AH1N1 cases under study when evaluated versus controlled cases. Deficiency of selenium is progressively observed from controls I (influenza like illness) through controls II (pneumonia) and finally pneumonia-AH1N1 infected patients. Cases with blood Se levels greater than the recommended for an optimal cut-off to activate glutathione peroxidase (12.5 µg/dL) recovered from illness and survived. Evaluation of this essential element in critical pneumonia patients at the National Institutes is under evaluation as a clinical trial.

Muscle biopsy features in critical ill patients with 2009 influenza A (H1N1) virus infection.

Higher serum creatine kinase (CK) levels in critically ill patients with a confirmed 2009 influenza A (H1N1) infection suggests a possible relationship between the H1N1 virus and muscle tissue. However, there have been no reports with an emphasis on muscle biopsies for patients infected with the H1N1 virus. The objective of this study was to investigate the histological characteristics of the muscle biopsies from critically ill patients with confirmed 2009 H1N1 infections. A series of ten patients with confirmed 2009 H1N1 infection, who presented increased serum CK levels, was analyzed. Histological study found small histochemical alterations in muscles fibers (mainly in NADH, SDH, COX, myophosphorylase, adenylate deaminase and PAS stains), and no histological changes were compatible with inflammatory myopathy. Although our critically ill patients had elevated CK levels, they exhibited few histological/histochemical abnormalities in their muscle biopsy samples; however, those alterations could be consistent with metabolic dysfunction associated with influenza H1N1 infection.

Muscle biopsy features in critical ill patients with 2009 influenza A (H1N1) virus infection / Alterações da biópsia muscular em pacientes gravemente acometidos pela infecção por vírus influenza A (H1N1) 2009

Higher serum creatine kinase (CK) levels in critically ill patients with a confirmed 2009 influenza A (H1N1) infection suggests a possible relationship between the H1N1 virus and muscle tissue. However, there have been no reports with an emphasis on muscle biopsies for patients infected with the H1N1 virus. The objective of this study was to investigate the histological characteristics of the muscle biopsies from critically ill patients with confirmed 2009 H1N1 infections. A series of ten patients with confirmed 2009 H1N1 infection, who presented increased serum CK levels, was analyzed. Histological study found small histochemical alterations in muscles fibers (mainly in NADH, SDH, COX, myophosphorylase, adenylate deaminase and PAS stains), and no histological changes were compatible with inflammatory myopathy. Although our critically ill patients had elevated CK levels, they exhibited few histological/histochemical abnormalities in their muscle biopsy samples; however, those alterations could be consistent with metabolic dysfunction associated with influenza H1N1 infection.

Os elevados níveis séricos da creatina quinase (CK) em pacientes gravemente acometidos pela infecção por influenza A (H1N1) 2009 sugerem uma possível relação entre infecção pelo vírus H1N1 e alterações do tecido muscular. No entanto, não existem relatos com ênfase nas alterações histológicas encontradas no músculo dos pacientes infectados pelo vírus H1N1. O objetivo deste estudo foi investigar as características histológicas, em biópsia muscular, de pacientes gravemente acometidos pela infecção por vírus H1N1 2009. Foi analisada uma série de dez pacientes com infecção confirmada por vírus H1N1, que apresentavam nível sérico elevado de CK. O estudo histológico evidenciou pequenas alterações histoquímicas nas fibras musculares (mais evidentes nas colorações por NADH, SDH, COX, miofosforilase, adenilato deaminase e PAS) mas sem alterações histológicas compatíveis com miopatia inflamatória. Embora nossos pacientes mostrassem níveis séricos elevados de CK, foram poucas as alterações histológicas e histoquímicas encontradas em suas biópsias musculares. Contudo, essas alterações podem ser consistentes com uma disfunção metabólica da fibra muscular associada à infecção pelo H1N1.

Utility of the tourniquet test and the white blood cell count to differentiate dengue among acute febrile illnesses in the emergency room.

Dengue often presents with non-specific clinical signs, and given the current paucity of accurate, rapid diagnostic laboratory tests, identifying easily obtainable bedside markers of dengue remains a priority. Previous studies in febrile Asian children have suggested that the combination of a positive tourniquet test (TT) and leucopenia can distinguish dengue from other febrile illnesses, but little data exists on the usefulness of these tests in adults or in the Americas. We evaluated the diagnostic accuracy of the TT and leucopenia (white blood cell count <5000/mm(3)) in identifying dengue as part of an acute febrile illness (AFI) surveillance study conducted in the Emergency Department of Saint Luke's Hospital in Ponce, Puerto Rico. From September to December 2009, 284 patients presenting to the ED with fever for 2-7 days and no identified source were enrolled. Participants were tested for influenza, dengue, leptospirosis and enteroviruses. Thirty-three (12%) patients were confirmed as having dengue; 2 had dengue co-infection with influenza and leptospirosis, respectively. An infectious etiology was determined for 141 others (136 influenza, 3 enterovirus, 2 urinary tract infections), and 110 patients had no infectious etiology identified. Fifty-two percent of laboratory-positive dengue cases had a positive TT versus 18% of patients without dengue (P<0.001), 87% of dengue cases compared to 28% of non-dengue cases had leucopenia (P<0.001). The presence of either a positive TT or leucopenia correctly identified 94% of dengue patients. The specificity and positive predictive values of these tests was significantly higher in the subset of patients without pandemic influenza A H1N1, suggesting improved discriminatory performance of these tests in the absence of concurrent dengue and influenza outbreaks. However, even during simultaneous AFI outbreaks, the absence of leucopenia combined with a negative tourniquet test may be useful to rule out dengue.

Initial clinical management of symptomatic adult patients during influenza A (H1N1) epidemics.

BACKGROUND: Pandemic influenza A (H1N1) has emerged rapidly in Argentina since May 2009. Preliminary comparisons with seasonal influenza suggest that H1N1 disproportionately affects younger patients, generally causing mild disease, but in a minority of cases can be lethal. OBJECTIVE: The aim of this study was to develop a clinical tool for the initial management of patients with influenza-like syndrome, within the context of the novel H1N1 virus epidemic, to detect patients who need further investigation (e.g., chest X-ray study) for the diagnosis of pneumonia. METHODS: We prospectively studied 1090 consecutive patients with influenza-like syndrome for a period of 15 days. Based on the presence of inspiratory crackles and the level of transcutaneous pulse oximetry, we selected 217 patients requiring chest X-ray study, and pneumonia was confirmed in all of these patients. RESULTS: Among the patients with pneumonia, 132 viral diagnostic tests were available, from which specimens tested by real-time reverse-transcriptase polymerase-chain reaction (RTPCR) were positive for H1N1 in 61 patients (46%). Comparison between RTPCR-positive and RTPCR-negative patients did not show any significant difference. Eighty-seven randomly selected patients with influenza-like syndrome, but without crackles and with O(2) saturation>96%, received chest X-ray studies; none demonstrated pulmonary infiltrates. CONCLUSION: Within the context of an influenza epidemic with the new H1N1 virus, the use of two simple and accessible clinical signs permits a rapid differentiation between those patients requiring close monitoring vs. those with mild and self-resolving disease.

[Experience in the management of the severe form of human influenza A H1N1 pneumonia in an intensive care unit].

BACKGROUND: At the beginning of the second trimester of 2009 there was an influenza A (H1N1) outbreak. The aim of this study is to describe the clinical presentation and mortality of the severe form of pneumonia in patients with human influenza A H1N1. METHODS: We conducted a retrospective review of all files of confirmed and suspected patients with severe human influenza A (H1N1) pneumonia. RESULTS: We studied 26 patients admitted to the ICU from April 1 to December 31, 2009, among which 16 were males (61.54%) and 10 females (38.46%) with an average age of 52.26 ± 15.48 years. The time of onset of symptoms to admission to the ICU was 6.3 ± 3.19 days. The most frequent symptoms and signs were salmonated sputum (47%), chills (45%), dry cough (44%) and myalgia (42%). The mortality rate was 19.23%. The treatment was based on antiviral therapy, modulating inflammation and ventilatory techniques to optimize oxygenation. There was an association between combined therapy based on methylprednisolone, activated protein C and statins with a better survival (p = 0.05). CONCLUSIONS: Pneumonia virus of human influenza A (H1N1) is associated with high morbidity and mortality. According to our results, it is recommended to make an early diagnosis and to initiate a treatment regimen based on treatment bundles designed to optimize oxygenation, reduce viral load and modulate inflammation.

Severe pandemic 2009 H1N1 influenza disease due to pathogenic immune complexes.

Pandemic influenza viruses often cause severe disease in middle-aged adults without preexisting comorbidities. The mechanism of illness associated with severe disease in this age group is not well understood. Here we find preexisting serum antibodies that cross-react with, but do not protect against, 2009 H1N1 influenza virus in middle-aged adults. Nonprotective antibody is associated with immune complex-mediated disease after infection. We detected high titers of serum antibody of low avidity for H1-2009 antigen, and low-avidity pulmonary immune complexes against the same protein, in severely ill individuals. Moreover, C4d deposition--a marker of complement activation mediated by immune complexes--was present in lung sections of fatal cases. Archived lung sections from middle-aged adults with confirmed fatal influenza 1957 H2N2 infection revealed a similar mechanism of illness. These observations provide a previously unknown biological mechanism for the unusual age distribution of severe cases during influenza pandemics.

[Direct immunofluorescence assay performance in diagnosis of the Influenza A(H1N1) virus]. / Desempeño de la prueba de inmunofluorescencia directa en el diagnóstico del virus Influenza A(H1N1).

By 25 April 2009, less than one month after the first human with Influenza A(H1N1) virus was detected in Mexico, the disease had already spread to more than 40 countries, with over 10,000 cases reported. Due to its unpredictability, this type of virus requires appropriate, reliable, and safe diagnostic methods that are also accessible to clinical laboratories. Through the analysis of 291 samples taken from patients with suspected Influenza A(H1N1) virus infection in Neuquén, Argentina, this study compares the two diagnostic methods used simultaneously: direct immunofluorescence assay (DFA) and real-time polymerase chain reaction (RT-PCR). DFA had a sensitivity of 44.4%, a specificity of 99.6%, a positive predictive value of 95.2%, and a negative predictive value of 90.7%. Positive results obtained with this method can be considered true positives. A negative result does not rule out the presence of the virus. In this case, the sample should be examined by RT-PCR. Out of a total of 291 samples, there were 45 positive results with RT-PCR and 21 positive results with DFA.

Desempeño de la prueba de inmunofluorescencia directa en el diagnóstico del virus Influenza A(H1N1) / Direct immunofluorescence assay performance in diagnosis of the Influenza A(H1N1) virus

El 25 de abril de 2009, a menos de un mes de la detección en México del primer humano con virus Influenza A(H1N1), la enfermedad ya se había propagado a más de 40 países superando los 10 000 casos notificados. Dada su naturaleza impredecible, este tipo de virus requiere métodos diagnósticos apropiados, confiables y seguros, pero que también estén al alcance de los laboratorios clínicos. Mediante el estudio de 291 muestras de pacientes con sospecha de infección por virus Influenza A(H1N1) en Neuquén, Argentina, el presente trabajo compara los dos métodos de diagnóstico utilizados simultáneamente: la prueba de inmunofluorescencia directa (DFA) y la de reacción en cadena de la polimerasa en tiempo real (RT-PCR). La DFA dio una sensibilidad de 44,4 por ciento, especificidad de 99,6 por ciento, valor predictivo positivo de 95,2 por ciento y valor predictivo negativo de 90,7 por ciento. Los resultados positivos de la metodología pueden considerarse verdaderos positivos. Un resultado negativo no excluye la presencia del virus y la muestra debe examinarse mediante RT-PCR. Del total de 291 muestras, 45 resultaron positivas por RT-PCR y 21 por DFA.

By 25 April 2009, less than one month after the first human with Influenza A(H1N1) virus was detected in Mexico, the disease had already spread to more than 40 countries, with over 10 000 cases reported. Due to its unpredictability, this type of virus requires appropriate, reliable, and safe diagnostic methods that are also accessible to clinical laboratories. Through the analysis of 291 samples taken from patients with suspected Influenza A(H1N1) virus infection in Neuquén, Argentina, this study compares the two diagnostic methods used simultaneously: direct immunofluorescence assay (DFA) and real-time polymerase chain reaction (RT-PCR). DFA had a sensitivity of 44.4 percent, a specificity of 99.6 percent, a positive predictive value of 95.2 percent, and a negative predictive value of 90.7 percent. Positive results obtained with this method can be considered true positives. A negative result does not rule out the presence of the virus. In this case, the sample should be examined by RT-PCR. Out of a total of 291 samples, there were 45 positive results with RT-PCR and 21 positive results with DFA.

Comparison of total white blood cell count and serum C-reactive protein levels in confirmed bacterial and viral infections.

We report the association of reaction in inflammatory markers with the microbiologic etiology of infection in children. Total white blood cell counts were increased in most pneumococcal and Escherichia coli infections, but in less than one-half of Staphylococcus aureus infections. Adenoviruses were the only viral agents that often increased total white blood cell counts or serum C-reactive protein levels.