Highly pathogenic avian influenza A(H5N1) virus of clade 2.3.4.4b isolated from a human case in Chile causes fatal disease and transmits between co-housed ferrets.

Clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) viruses have caused large outbreaks within avian populations on five continents, with concurrent spillover into a variety of mammalian species. Mutations associated with mammalian adaptation have been sporadically identified in avian isolates, and more frequently among mammalian isolates following infection. Reports of human infection with A(H5N1) viruses following contact with infected wildlife have been reported on multiple continents, highlighting the need for pandemic risk assessment of these viruses. In this study, the pathogenicity and transmissibility of A/Chile/25945/2023 HPAI A(H5N1) virus, a novel reassortant with four gene segments (PB1, PB2, NP, MP) from North American lineage, isolated from a severe human case in Chile, was evaluated in vitro and using the ferret model. This virus possessed a high capacity to cause fatal disease, characterized by high morbidity and extrapulmonary spread in virus-inoculated ferrets. The virus was capable of transmission to naïve contacts in a direct contact setting, with contact animals similarly exhibiting severe disease, but did not exhibit productive transmission in respiratory droplet or fomite transmission models. Our results indicate that the virus would need to acquire an airborne transmissible phenotype in mammals to potentially cause a pandemic. Nonetheless, this work warrants continuous monitoring of mammalian adaptations in avian viruses, especially in strains isolated from humans, to aid pandemic preparedness efforts.

Influenza aviar H5N1. ¿Debemos preocuparnos? / Avian influenza H5N1. Should we worry?

Desde la segunda mitad de 2022 se ha reportado un aumento de casos de influenza en aves migratorias en Latinoamérica. Los virus influenza A y B son los principales agentes asociados a influenza estacional epidémica en humanos. Los virus influenza A circulan no solo en humanos sino también en animales, incluyendo aves migratorias. El intercambio de segmentos de ARN genómico entre dos virus del mismo tipo aumenta la diversidad de los subtipos circulantes e incluso puede facilitar la generación de progenie viral potencialmente pandémica. La naturaleza zoonótica del virus influenza A puede generar infecciones en humanos con virus de origen animal. El virus influenza A de origen aviar ha ocasionado transmisiones en humanos, incluyendo casos graves y muertes, siendo la influenza A H5N1 la más destacada. Es importante tomar medidas de prevención y control en caso de aumento de casos de influenza en aves migratorias para prevenir posibles pandemias en Chile y el mundo.

Since the second half of 2022, an increase in influenza cases in migratory birds has been reported in Latin America. Influenza A and B viruses are the main agents associated with seasonal epidemic influenza in humans. Influenza A viruses circulate not only in humans but also in animals, including migratory birds. The exchange of genomic RNA segments among two viruses increases the diversity of circulating subtypes and may even facilitate the generation of potentially pandemic viral progeny. The zoonotic nature of influenza A virus can generate infections in humans with animal-origin viruses. Avian-origin influenza A virus has caused transmissions in humans, including severe cases and deaths, with influenza A H5N1 being the most prominent. It is important to take preventive and control measures in case of an increase in influenza cases in migratory birds to prevent possible pandemics in Chile and the world.

Nota Técnica N. 3/2023 - SES/GVEDT: Nota técnica de Síndrome Gripal (SG) e Síndrome Respiratória Aguda Grave (SRAG) pelo vírus influenza / Technical Note N. 3/2023 - SES/GVEDT: Technical Note on Influenza Syndrome (SG) and Severe Acute Respiratory Syndrome (SARS) due to the influenza virus

A vigilância d influenza no Brasil é composta pela vigilância sentinela de Síndrome Gripal (SG), Síndrome Respiratória Grave (SRAG) em pacientes hospitalizados ou óbitos e em surtos de SG em instituições e de longa permanência. As unidade sentinelas de Síndrome Gripal têm como objetivo monitorar a circulação dos vírus respiratórios com ênfase em influenza e Sars-CoV-2, identificar as variações sazonais por faixa etária, prover cepas virais para formulação de vacinas de influenza, vigilância genômica do coronavírus, e identificar situações inusitadas

Influenza surveillance in Brazil is composed of sentinel surveillance of Influenza Syndrome (SG), Severe Respiratory Syndrome (SARS) in hospitalized or deceased patients and in SG outbreaks in institutions and long-term care facilities. The flu syndrome sentinel units aim to monitor the circulation of respiratory viruses with emphasis on influenza and Sars-CoV-2, identify seasonal variations by age group, provide viral strains for the formulation of influenza vaccines, genomic surveillance of the coronavirus, and identify unusual situations

Covid-19 y gripe de 1918-1919: paralelos históricos, preguntas y respuestas / Covid-19 and the 1918-1919 influenza: historical parallels, questions and answers

Resumen El desarrollo de la pandemia de la covid-19 ha motivado un renovado interés por la gripe de 1918-1919 para buscar elementos que facilitaran la comprensión de la experiencia presente, pero también como oportunidad para reevaluar la grave crisis sanitaria del siglo XX a la luz de lo que estamos viviendo. En este contexto y con ese objetivo se inserta esta reflexión histórica sobre estos dos fenómenos pandémicos, que muestra los paralelismos existentes y la necesidad de una toma de conciencia de que nuestro modelo de sociedad está en crisis y se requiere una transformación profunda.

Abstract The rise of the covid-19 pandemic has led to renewed interest in the 1918-1919 influenza in search of aspects that might help us understand the current situation, but also as an opportunity to re-evaluate the serious twentieth-century health crisis in light of what we are experiencing now. In this context and with that goal, this historical reflection shows the parallels that exist and the need for a realization that our model of society is undergoing a crisis and requires profound transformation.

Knowledge, attitudes, and practices for the use of seasonal influenza vaccination, healthcare workers, Costa Rica.

INTRODUCTION: Annual seasonal influenza vaccination in healthcare workers prevents nosocomial transmission to patients, coworkers, and visitors, and reduces absenteeism. This study aimed to describe knowledge, attitudes, and practices (KAP) of seasonal influenza vaccine among public healthcare workers attending patients in Costa Rica. METHODOLOGY: We conducted a cross-sectional survey of healthcare personnel attending patients in public hospitals in 2017-2018. Frequency distributions of demographics, vaccination KAP, sources of information, clinical manifestations and reasons for non-vaccination were reported. Logistic regression was used to analyze associations between exposures of interest (demographics, sources of information, knowledge, attitudes towards vaccination) and self-reported influenza vaccination. RESULTS: We surveyed 747 healthcare workers in 2017-2018. Of 706 participants who knew their vaccination status, 55.7% were vaccinated for seasonal influenza. Only 20.7% of participants knew the influenza vaccine was an inactivated virus, and 94.6% believed the vaccine causes flu-like symptoms. Factors associated with current influenza vaccination were vaccination in previous year (aOR: 8.13; 95% CI: 5.65-11.71) and believed influenza vaccination may be harmful (aOR: 0.62; 95% CI: 0.44-0.89). Reasons for non-vaccination included fear of adverse effects and access limitations. CONCLUSIONS: Suboptimal influenza vaccination among healthcare workers may be attributed to misconceptions about the vaccine and limited engagement strategies focusing on healthcare workers. Appropriate interventions are needed to increase healthcare worker vaccination rates and improve their knowledge and beneficence, which would improve patient safety in hospitals.

[Covid-19 and the 1918-1919 influenza: historical parallels, questions and answers]. / Covid-19 y gripe de 1918-1919: paralelos históricos, preguntas y respuestas.

The rise of the covid-19 pandemic has led to renewed interest in the 1918-1919 influenza in search of aspects that might help us understand the current situation, but also as an opportunity to re-evaluate the serious twentieth-century health crisis in light of what we are experiencing now. In this context and with that goal, this historical reflection shows the parallels that exist and the need for a realization that our model of society is undergoing a crisis and requires profound transformation.

El desarrollo de la pandemia de la covid-19 ha motivado un renovado interés por la gripe de 1918-1919 para buscar elementos que facilitaran la comprensión de la experiencia presente, pero también como oportunidad para reevaluar la grave crisis sanitaria del siglo XX a la luz de lo que estamos viviendo. En este contexto y con ese objetivo se inserta esta reflexión histórica sobre estos dos fenómenos pandémicos, que muestra los paralelismos existentes y la necesidad de una toma de conciencia de que nuestro modelo de sociedad está en crisis y se requiere una transformación profunda.

Absence of detection of RSV and influenza during the COVID-19 pandemic in a Brazilian cohort: Likely role of lower transmission in the community.

BACKGROUND: Respiratory syncytial virus (RSV) and influenza are prevalent seasonal community viruses. Although not completely understood, SARS-CoV-2 may have the same means of transmission. Preventive social measures aimed at preventing SARS-CoV-2 spread could impact transmission of other respiratory viruses as well. The aim of this study is to report the detection of RSV and influenza during the period of social distancing due to COVID-19 pandemic in a heavily affected community. METHODS: Prospective study with pediatric and adult populations seeking care for COVID-19-like symptoms during the fall and winter of 2020 at two hospitals in Southern Brazil. RT-PCR tests for SARS-CoV-2, influenza A (Flu A), influenza B (Flu B) and respiratory syncytial virus (RSV) was performed for all participants. RESULTS: 1435 suspected COVID-19 participants (1137 adults, and 298 children). were included between May and August. Median age was 37.7 years (IQR = 29.6-47.7), and 4.92 years (IQR = 1.96-9.53), for the adult and child cohorts, respectively. SARS-CoV-2 was positive in 469 (32.7%) while influenza and RSV were not detected at all. CONCLUSIONS: Measures to reduce SARS-CoV-2 transmission likely exerted a huge impact in the spread of alternate respiratory pathogens. These findings contribute to the knowledge about the dynamics of virus spread. Further, it may be considered for guiding therapeutic choices for these other viruses.

[Proposal for territorial analysis to face the SARS-CoV-2 pandemic based on the Profile of pneumonia and Influenza in Ecuador 2016-2018]. / Propuesta de análisis territorial para enfrentar la pandemia por SARS-CoV-2 basado en el perfil de neumonía e influenza en Ecuador 2016-2018.

OBJECTIVE: The present study seeks to analyse sociodemographic determinants related to severe acute respiratory infections (SARI) and calculate the priorization index in the cantons of Ecuador to identify areas probably most vulnerable to COVID-19 transmission. DESIGN: This descriptive ecological observational study. SETTING: 224 cantons (geographical area) of Ecuador with secondary data sources of hospital information. PARTICIPANTS: The unit of measurement was 224 cantons of Ecuador, in which analysed morbidity and lethality rates for SARI using hospital release data (2016-2018). MAIN MEASUREMENTS: Eight sociodemographic indicators were structuralized, and correlation tests applied for a multiple regression model. The priorization index was created with criteria of efficiency, efficacy, effect size (IRR) and equity. Using the sum of the index for each indicator, the priorization score was calculated and localized in a territorial map. RESULTS: Morbidity associated factors where: school attendance years, urbanization and population density; for mortality resulted: school attendance and ethnics (indigenous) IRR: 1.09 (IC95%:1.06-1.15) and IRR: 1.024 (IC95%:102-1.03) respectively. With lethality where related cantons, with population older than 60 years, IRR: 1.049 (IC95%: 1.03-1.07); 87 cantons had high priority mostly localized in the mountain region and the Morona Santiago Province. CONCLUSIONS: Morbidity and mortality of SARI in Ecuador are associated to social and demographic factors. Priorization exercises considering these factors permit the identification of vulnerable territories facing respiratory disease propagation. The social determinants characteristic for each territory should be added to known individual factors to analyse the risk and vulnerability for COVID in the population.

How the individual human mobility spatio-temporally shapes the disease transmission dynamics.

Human mobility plays a crucial role in the temporal and spatial spreading of infectious diseases. During the past few decades, researchers have been extensively investigating how human mobility affects the propagation of diseases. However, the mechanism of human mobility shaping the spread of epidemics is still elusive. Here we examined the impact of human mobility on the infectious disease spread by developing the individual-based SEIR model that incorporates a model of human mobility. We considered the spread of human influenza in two contrasting countries, namely, Belgium and Martinique, as case studies, to assess the specific roles of human mobility on infection propagation. We found that our model can provide a geo-temporal spreading pattern of the epidemics that cannot be captured by a traditional homogenous epidemic model. The disease has a tendency to jump to high populated urban areas before spreading to more rural areas and then subsequently spread to all neighboring locations. This heterogeneous spread of the infection can be captured by the time of the first arrival of the infection [Formula: see text], which relates to the landscape of the human mobility characterized by the relative attractiveness. These findings can provide insights to better understand and forecast the disease spreading.

[Therapeutic remedies and medical propaganda on influenza in Mexico in 1918: ideas and knowledge sets]. / Remedios curativos y propaganda médica contra la influenza de 1918 en México: ideas y conocimientos.

This article explores medical thought on the impact of the influenza pandemic of 1918 in Mexico. It analyzes scientific ideas on the etiology of the flu, as reflected in the types of remedies and medical prescriptions published in the press and in health bulletins. It then goes deeper into the topic by examining the international historic context, dominated by the war. In Mexico, years of armed conflict unleashed by the Revolution exacerbated living conditions among the population: starvation, typhus, smallpox and other infectious diseases were present before and during the outbreak of the pandemic. This study is based on archival documentation, health bulletins, press sources from the period, and modern bibliography.

Remedios curativos y propaganda médica contra la influenza de 1918 en México: ideas y conocimientos / Therapeutic remedies and medical propaganda on influenza in Mexico in 1918: ideas and knowledge sets

Resumen El artículo explora el pensamiento médico en torno al impacto de la pandemia de influenza de 1918 en México. Se analizan las ideas científicas sobre la etiología de la gripe, las cuales se reflejaron en el tipo de remedios y recetas médicas que se publicaron en la prensa y en boletines de salud. Para adentrarse en este tema profundizamos en el contexto histórico internacional dominado por la guerra. En México, años de conflictos armados a consecuencia de la Revolución agravaron las condiciones de vida de la población: hambre, tifo, viruela y otros padecimientos infecciosos se presentaron antes y durante el brote de la pandemia. El trabajo se apoya en documentación de archivo, boletines de salud, prensa de la época y bibliografía actualizada.

Abstract This article explores medical thought on the impact of the influenza pandemic of 1918 in Mexico. It analyzes scientific ideas on the etiology of the flu, as reflected in the types of remedies and medical prescriptions published in the press and in health bulletins. It then goes deeper into the topic by examining the international historic context, dominated by the war. In Mexico, years of armed conflict unleashed by the Revolution exacerbated living conditions among the population: starvation, typhus, smallpox and other infectious diseases were present before and during the outbreak of the pandemic. This study is based on archival documentation, health bulletins, press sources from the period, and modern bibliography.

Eco-Epidemiological Evidence of the Transmission of Avian and Human Influenza A Viruses in Wild Pigs in Campeche, Mexico.

Influenza, a zoonosis caused by various influenza A virus subtypes, affects a wide range of species, including humans. Pig cells express both sialyl-α-2,3-Gal and sialyl-α-2,6-Gal receptors, which make them susceptible to infection by avian and human viruses, respectively. To date, it is not known whether wild pigs in Mexico are affected by influenza virus subtypes, nor whether this would make them a potential risk of influenza transmission to humans. In this work, 61 hogs from two municipalities in Campeche, Mexico, were sampled. Hemagglutination inhibition assays were performed in 61 serum samples, and positive results were found for human H1N1 (11.47%), swine H1N1 (8.19%), and avian H5N2 (1.63%) virus variants. qRT-PCR assays were performed on the nasal swab, tracheal, and lung samples, and 19.67% of all hogs were positive to these assays. An avian H5N2 virus, first reported in 1994, was identified by sequencing. Our results demonstrate that wild pigs are participating in the exposure, transmission, maintenance, and possible diversification of influenza viruses in fragmented habitats, highlighting the synanthropic behavior of this species, which has been poorly studied in Mexico.

Epidemic dynamics of respiratory syncytial virus in current and future climates.

A key question for infectious disease dynamics is the impact of the climate on future burden. Here, we evaluate the climate drivers of respiratory syncytial virus (RSV), an important determinant of disease in young children. We combine a dataset of county-level observations from the US with state-level observations from Mexico, spanning much of the global range of climatological conditions. Using a combination of nonlinear epidemic models with statistical techniques, we find consistent patterns of climate drivers at a continental scale explaining latitudinal differences in the dynamics and timing of local epidemics. Strikingly, estimated effects of precipitation and humidity on transmission mirror prior results for influenza. We couple our model with projections for future climate, to show that temperature-driven increases to humidity may lead to a northward shift in the dynamic patterns observed and that the likelihood of severe outbreaks of RSV hinges on projections for extreme rainfall.

Spatiotemporal Analysis of Influenza Morbidity and Its Association with Climatic and Housing Conditions in Ecuador.

The external environment directly influences human health. However, what happens inside? This work deals with the effect that the interior thermal variables have on the propagation of respiratory diseases and focused on the relation of the temperature and relative humidity inside social housing in the 1040 parishes of Ecuador and the transmission of influenza. On the one hand, historical weather-related variables were used to simulate and estimate the interior conditions, and thresholds on temperature and humidity were determined. On the other hand, the health-related variable was determined by analyzing the statistics corresponding to the influenza and viral pneumonia in 2009 since that year was critical for these diseases; the data were divided by month for each parish. Finally, the correlation of these variables determines the relative importance of the interior conditions on the respiratory health of its inhabitants. The preliminary results indicate that the places with the lowest temperatures and relative humidity could favor the virus transmission. Also, the analysis indicated that respiratory diseases increase in August and October. In this way, it is clear that social housing projects in Ecuador require a study which guarantees not only energy efficiency and sustainability related issues but also the well-being of their inhabitants.

The respiratory microbiota: associations with influenza symptomatology and viral shedding.

PURPOSE: Manifestations of infection and the degree of influenza virus vary. We hypothesized that the nose/throat microbiota modifies the duration of influenza symptoms and viral shedding. Exploring these relationships may help identify additional methods for reducing influenza severity and transmission. METHODS: Using a household transmission study in Nicaragua, we identified secondary cases of influenza virus infection, defined as contacts with detectable virus or a greater than 4-fold change in hemagglutinin inhibition antibody titer. We characterized the nose/throat microbiota of secondary cases before infection and explored whether the duration of symptoms and shedding differed by bacterial community characteristics. RESULTS: Among 124 secondary cases of influenza, higher bacterial community diversity before infection was associated with longer shedding duration (Shannon acceleration factor [AF]: 1.61, 95% confidence interval [CI]: 1.24, 2.10) and earlier time to infection (Shannon AF: 0.72, 95% CI: 0.53, 0.97; Chao1 AF: 0.992, 95% CI: 0.986, 0.998). Neisseria and multiple other oligotypes were significantly associated with symptom and shedding durations and time to infection. CONCLUSIONS: The nose/throat microbiota before influenza virus infection was associated with influenza symptoms and shedding durations. Further studies are needed to determine if the nose/throat microbiota is a viable target for reducing influenza symptoms and transmission.

The 1918 influenza pandemic in Montevideo: The southernmost capital city in the Americas.

BACKGROUND: Few studies have addressed the impact and dynamics of the 1918-1919 influenza pandemic in temperate regions of South America. OBJECTIVE: To identify key factors for influenza onset, spread, and mortality in Montevideo and Uruguay in 1918-1919. METHODS: An analysis of official national records of the public health system of Uruguay was performed. RESULTS: From November to December of 1918 (spring), a total of 131 deaths due to influenza occurred in Montevideo and a total of 296 deaths accounted from July to September of 1919 (winter) in the same city. The total deaths attributed to influenza in Uruguay in 1918 and 1919 were 926 and 1089, respectively. In contrast, the mean annual mortality attributed to influenza in Uruguay from 1908 to 1917 was 50.9. A pattern of age-shift in mortality in the two pandemic waves studied was observed. CONCLUSIONS: The results of studies revealed that Montevideo was first hit by the devastating second wave of the pandemic of 1918, arriving Montevideo at the end of the spring of that year. The third wave arrived by July 1919, in the winter season, and in the capital city was as severe as the second one.

Severe acute respiratory infections (SARI) from influenza in adult patients in Chile: the experience of a sentinel hospital / La infección respiratoria aguda grave asociada a la gripe en pacientes adultos en Chile: experiencia de un hospital centinela / Infecção respiratória aguda grave (SARI) decorrente da influenza em pacientes adultos no Chile: experiência de um hospital-sentinela

ABSTRACT Objective To 1) describe clinical characteristics of adult patients in Chile with severe acute respiratory infections (SARI) associated with influenza viruses, and 2) analyze virus subtypes identified in specimens collected from those patients, hospital resources used in clinical management, clinical evolution, and risk factors associated with a fatal outcome, using observational data from the SARI surveillance network (SARInet). Methods Adults hospitalized from 1 July 2011 to 31 December 2015 with influenza-associated SARI at a SARI sentinel surveillance hospital in Santiago were identified and the presence of influenza in all cases confirmed by reverse transcription polymerase chain reaction (RT-PCR), using respiratory samples. Results A total of 221 patients (mean age: 74.1 years) were hospitalized with influenza-associated SARI during the study period. Of this study cohort, 91.4% had risk factors for complications and 34.3% had been vaccinated during the most recent campaign. Pneumonia was the most frequent clinical manifestation, occurring in 57.0% of the cohort; other manifestations included influenza-like illness, exacerbated chronic bronchitis, decompensated heart failure, and asthmatic crisis. Cases occurred year-round, with an epidemic peak during autumn-winter. Both influenza A (H1N1pdm09 and H3N2) and B virus co-circulated. Critical care beds were required for 26.7% of the cohort, and 19.5% needed ventilatory assistance. Multivariate analysis identified four significant factors associated with in-hospital mortality: 1) being bedridden (adjusted odds ratio (aOR): 22.3; 95% confidence interval (CI): 3.0-164); 2) admission to critical care unit (aOR: 8.9; CI: 1.44-55); 3) Pa02/Fi02 ratio < 250 (aOR: 5.8; CI: 1.02-33); and 4) increased serum creatinine concentration (> 1 mg/dL) (aOR: 5.47; CI: 1.20-24). Seasonal influenza vaccine was identified as a significant protective factor (aOR: 0.14; CI: 0.021-0.90). Conclusions Influenza-associated SARI affected mainly elderly patients with underlying conditions. Most patients evolved to respiratory failure and more than one-quarter required critical care beds. Clinical presentation was variable. Death was associated with host characteristics and disease-associated conditions, and vaccine was protective. Virus type did not influence outcome.

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RESUMO Objetivo Descrever as características clínicas de pacientes adultos com infecção respiratória aguda grave (SARI) associada ao vírus da influenza e analisar os subtipos virais identificados em amostras coletadas destes pacientes, os recursos hospitalares empregados no tratamento clínico, a evolução clínica e os fatores de risco clínicos associados a um desfecho fatal, a partir de dados observacionais da rede de vigilância de SARI (SARInet) no Chile. Métodos Foram identificados os adultos hospitalizados com SARI associada a influenza em um hospital-sentinela de vigilância de SARI, em Santiago, de 1o de julho de 2011 a 31 de dezembro de 2015. A ocorrência de influenza foi confirmada em amostras respiratórias em todos os casos com a reação em cadeia da polimerase via transcriptase reversa (RT-RCP). Resultados Ao todo, 221 pacientes (idade média de 74,1 anos) foram hospitalizados com SARI associada a influenza no período de estudo. Nesta coorte, 91,4% apresentavam fatores de risco para complicação e 34,3% haviam sido vacinados na última campanha de vacinação. Pneumonia foi a manifestação clínica mais frequente, ocorrendo em 57,0% da coorte. Outras manifestações foram doença gripal, bronquite crônica exacerbada, insuficiência cardíaca descompensada e crise asmática. Os casos estiveram distribuídos ao longo do ano, com pico epidêmico no outono-inverno. Houve circulação simultânea dos vírus da influenza A (H1N1pdm09 e H3N2) e B. Leitos de terapia intensiva foram necessários em 26,7% da coorte e suporte ventilatório, em 19,5%. Na análise multivariada, quatro fatores importantes associados à mortalidade hospitalar foram identificados: estar restrito ao leito (odds ratio ajustado [ORaj] 22.3; intervalo de confiança de 95% [IC 95%] 3.0-164); ser admitido na unidade de terapia intensiva (ORaj 8.9, IC 95% 1.4 4-55); relação Pa02/Fi02 <250 (ORaj 5.8; IC 95% 1.02-33) e aumento da creatinina sérica (>1 mg/dl) (ORaj 5.47; IC 95% 1.20-24). A vacinação sazonal contra influenza foi identificada como importante fator de proteção (ORaj 0.14; IC 95% 0.021-0.90). Conclusões A SARI associada a influenza acometeu sobretudo pacientes idosos com doenças preexistentes. A maioria dos pacientes evoluiu com insuficiência respiratória e mais de um quarto precisou de cuidados intensivos. O quadro clínico foi variável. Morte foi associada às características do hospedeiro e problemas relacionados à doença. A vacinação teve efeito protetor e o tipo viral não influiu no desfecho.

Influenza Transmission Dynamics in Urban Households, Managua, Nicaragua, 2012-2014.

During August 2012-November 2014, we conducted a case ascertainment study to investigate household transmission of influenza virus in Managua, Nicaragua. We collected up to 5 respiratory swab samples from each of 536 household contacts of 133 influenza virus-infected persons and assessed for evidence of influenza virus transmission. The overall risk for influenza virus infection of household contacts was 15.7% (95% CI 12.7%-19.0%). Oseltamivir treatment of index patients did not appear to reduce household transmission. The mean serial interval for within-household transmission was 3.1 (95% CI 1.6-8.4) days. We found the transmissibility of influenza B virus to be higher than that of influenza A virus among children. Compared with households with <4 household contacts, those with >4 household contacts appeared to have a reduced risk for infection. Further research is needed to model household influenza virus transmission and design interventions for these settings.

Spatiotemporal diffusion of influenza A (H1N1): Starting point and risk factors.

Influenza constitutes a major challenge to world health authorities due to high transmissibility and the capacity to generate large epidemics. This study aimed to characterize the diffusion process of influenza A (H1N1) by identifying the starting point of the epidemic as well as climatic and sociodemographic factors associated with the occurrence and intensity of transmission of the disease. The study was carried out in the Brazilian state of Paraná, where H1N1 caused the largest impact. The units of spatial and temporal analysis were the municipality of residence of the cases and the epidemiological weeks of the year 2009, respectively. Under the Bayesian paradigm, parametric inference was performed through a two-part spatiotemporal model and the integrated nested Laplace approximation (INLA) algorithm. We identified the most likely starting points through the effective distance measure based on mobility networks. The proposed estimation methodology allowed for rapid and efficient implementation of the spatiotemporal model, and provided evidence of different patterns for chance of occurrence and risk of influenza throughout the epidemiological weeks. The results indicate the capital city of Curitiba as the probable starting point, and showed that the interventions that focus on municipalities with greater migration and density of people, especially those with higher Human Development Indexes (HDIs) and the presence of municipal air and road transport, could play an important role in mitigation of effects of future influenza pandemics on public health. These results provide important information on the process of introduction and spread of influenza, and could contribute to the identification of priority areas for surveillance as well as establishment of strategic measures for disease prevention and control. The proposed model also allows identification of epidemiological weeks with high chance of influenza occurrence, which can be used as a reference criterion for creating an immunization campaign schedule.

Circulation of influenza in backyard productive systems in central Chile and evidence of spillover from wild birds.

Backyard productive systems (BPS) are recognized as the most common form of animal production in the world. However, BPS frequently exhibit inherent biosecurity deficiencies, and could play a major role in the epidemiology of animal diseases and zoonoses. The aim of this study was to determine if influenza A viruses (IAV) were prevalent in backyard poultry and swine BPS in central Chile. Through active surveillance in Valparaiso and Metropolitan regions from 2012 - 2014, we found that influenza virus positivity by real-time RT-PCR (qRT-PCR) ranged from 0% during winter 2012-45.8% during fall 2014 at the farm level. We also obtained an H12 hemagglutinin (HA) sequence of wild bird origin from a domestic Muscovy duck (Cairina moschata), indicating spillover from wild birds into backyard poultry populations. Furthermore, a one-year sampling effort in 113 BPS in the Libertador Bernardo O'Higgins (LGB ÓHiggins) region showed that 12.6% of poultry and 2.4% of swine were positive for IAV by enzyme-linked immunosorbent assay (ELISA), indicative of previous exposure of farm animals to IAV. This study highlights the need for improved IAV surveillance in backyard populations given the close interaction between domestic animals, wild birds and people in these farms, particularly in an understudied region, like South America.