BackgroundThe relationship between obesity and risk of complications described during the 2009 influenza pandemic is poorly defined for seasonal influenza and other viral causes of influenza‐like illness (ILI).MethodsAn observational cohort of hospitalized and outpatient participants with ILI was conducted in six hospitals in Mexico. Nasopharyngeal swabs were tested for influenza and other common respiratory pathogens.ResultsA total of 4778 participants were enrolled in this study and had complete data. A total of 2053 (43.0%) had severe ILI. Seven hundred and seventy‐eight (16.3%) were positive for influenza, 2636 (55.2%) were positive for other viral respiratory pathogens, and 1364 (28.5%) had no respiratory virus isolated. Adults with influenza were more likely to be hospitalized if they were underweight (OR: 5.20), obese (OR: 3.18), or morbidly obese (OR: 18.40) compared to normal‐weight adults. Obese adults with H1N1 had a sixfold increase in odds of hospitalization over H3N2 and B (obese OR: 8.96 vs 1.35, morbidly obese OR: 35.13 vs 5.58, respectively) compared to normal‐weight adults. In adults with coronavirus, metapneumovirus, parainfluenza, and rhinovirus, participants that were underweight (OR: 4.07) and morbidly obese (OR: 2.78) were more likely to be hospitalized as compared to normal‐weight adults. All‐cause influenza‐like illness had a similar but less pronounced association between underweight or morbidly obesity and hospitalization.ConclusionsThere is an increased risk of being hospitalized in adult participants that are underweight or morbidly obese, regardless of their viral pathogen status. Having influenza, however, significantly increases the odds of hospitalization in those who are underweight or morbidly obese.

Summary Background Influenza-like illnesses (ILI) are estimated to cause millions of deaths annually. Despite this disease burden, the etiologic causes of ILI are poorly described for many geographical regions. Methods Beginning in April 2010, we conducted an observational cohort study at five hospitals in Mexico City, enrolling subjects who met the criteria for ILI. Evaluations were conducted at enrollment and on day 28, with the collection of clinical data and a nasopharyngeal swab (or nasal aspirate in children). Swabs were tested by multiplex PCR for 15 viral pathogens and real-time PCR for influenza. Results During the first year, 1065 subjects were enrolled in this study, 55% of whom were hospitalized; 24% of all subjects were children. One or more pathogens were detected by PCR in 64% of subjects, most commonly rhinovirus (25% of all isolates) and influenza (24% of isolates). Six percent of subjects died, and of those, 54% had no pathogen identified. Rhinovirus was the most common pathogen among those who died, although it did not have the highest case fatality rate. Conclusions Multiple respiratory viruses beyond influenza are associated with significant morbidity and mortality among adults and children in Mexico City. Detection of these agents could be useful for the adjustment of antibiotic treatment in severe cases.

BackgroundRespiratory syncytial virus (RSV) is a leading etiological agent of acute respiratory tract infections and hospitalizations in children. However, little information is available regarding RSV infections in Latin American countries, particularly among adult patients.ObjectiveTo describe the epidemiology of RSV infection and to analyze the factors associated with severe infections in children and adults in Mexico.MethodsPatients ≥1 month old, who presented with an influenza‐like illness (ILI) to six hospitals in Mexico, were eligible for participation in the study. Multiplex reverse‐transcriptase polymerase chain reaction identified viral pathogens in nasal swabs from 5629 episodes of ILI. Patients in whom RSV was detected were included in this report.ResultsRespiratory syncytial virus was detected in 399 children and 171 adults. RSV A was detected in 413 cases and RSV B in 163, including six patients who had coinfection with both subtypes; 414 (72.6%) patients required hospital admission, including 96 (16.8%) patients that required admission to the intensive care unit. Coinfection with one or more respiratory pathogens other than RSV was detected in 159 cases. Young age (in children) and older age (in adults) as well as the presence of some underlying conditions were associated with more severe disease.ConclusionsThis study confirms that RSV is an important respiratory pathogen in children in Mexico. In addition, a substantial number of cases in adults were also detected highlighting the relevance of this virus in all ages. It is important to identify subjects at high risk of complications who may benefit from current or future preventive interventions.

Background. Molecular detection methods allow for the simultaneous detection of several infectious agents. This study assesses whether co-infection with 2 viruses as compared with 1 is associated with increased hospitalization in those with acute respiratory infections.Methods. We prospectively enrolled a cohort of pediatric and adult participants with influenza-like illness during 2010-2014 in Mexico. Clinical information and respiratory samples were collected at enrollment. Respiratory viruses were detected with multiplex polymerase chain reaction (PCR) and influenza-specific reverse transcription PCR assays. Participants were followed for 14 and 28 days after inclusion. Severity of disease, as measured by hospitalization with acute respiratory infections, was compared between single and dual viral infections.Results. Among 5662 participants in the study, either 1 (n = 3285) or 2 (n = 641) viruses were detected in 3926 participants. Rhinovirus (n = 1433), influenza (n = 888), and coronaviruses (n = 703) were the most frequently detected viruses (either alone or in co-infection). Bocavirus, respiratory syncytial virus (RSV), metapneumovirus, and rhinovirus cases were hospitalized more often than other viruses. Bocavirus+rhinovirus cases were hospitalized more often than those with rhinovirus alone (but not bocavirus alone). RSV cases were more likely to be hospitalized than cases with co-infections of RSV and parainfluenza virus or coronavirus. Metapneumovirus cases were hospitalized more often than those co-infected with metapneumovirus+coronavirus.Conclusions. In this study, detection of 2 viruses did not significantly increase hospitalizations compared with single virus infections. Larger studies will allow for distinguishing between sequential and simultaneous infection and for a better understanding of the role of each virus during the evolution of acute respiratory episodes.

Children presenting with ILI caused by RSV and metapneumovirus were at greatest risk for hospitalization, while children with rhinovirus/enterovirus, parainfluenza, coronavirus, adenovirus, and influenza were at lower risk of hospitalization.