Anthony W. Mounts

Global burden of respiratory infections due to seasonal influenza in young children: a systematic review and meta-analysis

BACKGROUNDnThe global burden of disease attributable to seasonal influenza virus in children is unknown. We aimed to estimate the global incidence of and mortality from lower respiratory infections associated with influenza in children younger than 5 years.nnnMETHODSnWe estimated the incidence of influenza episodes, influenza-associated acute lower respiratory infections (ALRI), and influenza-associated severe ALRI in children younger than 5 years, stratified by age, with data from a systematic review of studies published between Jan 1, 1995, and Oct 31, 2010, and 16 unpublished population-based studies. We applied these incidence estimates to global population estimates for 2008 to calculate estimates for that year. We estimated possible bounds for influenza-associated ALRI mortality by combining incidence estimates with case fatality ratios from hospital-based reports and identifying studies with population-based data for influenza seasonality and monthly ALRI mortality.nnnFINDINGSnWe identified 43 suitable studies, with data for around 8 million children. We estimated that, in 2008, 90 million (95% CI 49-162 million) new cases of influenza (data from nine studies), 20 million (13-32 million) cases of influenza-associated ALRI (13% of all cases of paediatric ALRI; data from six studies), and 1 million (1-2 million) cases of influenza-associated severe ALRI (7% of cases of all severe paediatric ALRI; data from 39 studies) occurred worldwide in children younger than 5 years. We estimated there were 28,000-111,500 deaths in children younger than 5 years attributable to influenza-associated ALRI in 2008, with 99% of these deaths occurring in developing countries. Incidence and mortality varied substantially from year to year in any one setting.nnnINTERPRETATIONnInfluenza is a common pathogen identified in children with ALRI and results in a substantial burden on health services worldwide. Sufficient data to precisely estimate the role of influenza in childhood mortality from ALRI are not available.nnnFUNDINGnWHO; Bill & Melinda Gates Foundation.

Risk Factors for Severe Outcomes following 2009 Influenza A (H1N1) Infection: A Global Pooled Analysis

This study analyzes data from 19 countries (from April 2009 to Jan 2010), comprising some 70,000 hospitalized patients with severe H1N1 infection, to reveal risk factors for severe pandemic influenza, which include chronic illness, cardiac disease, chronic respiratory disease, and diabetes.

Case-control study of risk factors for avian influenza A (H5N1) disease, Hong Kong, 1997

In May 1997, a 3-year-old boy in Hong Kong died of a respiratory illness related to influenza A (H5N1) virus infection, the first known human case of disease from this virus. An additional 17 cases followed in November and December. A case-control study of 15 of these patients hospitalized for influenza A (H5N1) disease was conducted using controls matched by age, sex, and neighborhood to determine risk factors for disease. Exposure to live poultry (by visiting either a retail poultry stall or a market selling live poultry) in the week before illness began was significantly associated with H5N1 disease (64% of cases vs. 29% of controls, odds ratio, 4.5, P=.045). By contrast, travel, eating or preparing poultry products, recent exposure to persons with respiratory illness, including persons with known influenza A (H5N1) infection, were not associated with H5N1 disease.

Risk of Influenza A (H5N1) Infection among Health Care Workers Exposed to Patients with Influenza A (H5N1), Hong Kong

The first outbreak of avian influenza A (H5N1) occurred among humans in Hong Kong in 1997. To estimate the risk of person-to-person transmission, a retrospective cohort study was conducted to compare the prevalence of H5N1 antibody among health care workers (HCWs) exposed to H5N1 case-patients with the prevalence among nonexposed HCWs. Information on H5N1 case-patient and poultry exposures and blood samples for H5N1-specific antibody testing were collected. Eight (3.7%) of 217 exposed and 2 (0.7%) of 309 nonexposed HCWs were H5N1 seropositive (P=.01). The difference remained significant after controlling for poultry exposure (P=.01). This study presents the first epidemiologic evidence that H5N1 viruses were transmitted from patients to HCWs. Human-to-human transmission of avian influenza may increase the chances for the emergence of a novel influenza virus with pandemic potential.

Global mortality estimates for the 2009 Influenza Pandemic from the GLaMOR project: a modeling study.

Lone Simonsen and colleagues use a two-stage statistical modeling approach to estimate the global mortality burden of the 2009 influenza pandemic from mortality data obtained from multiple countries. Please see later in the article for the Editors Summary

Highly Pathogenic Avian Influenza (H5N1): Pathways of Exposure at the Animal‐Human Interface, a Systematic Review

Background The threat posed by highly pathogenic avian influenza A H5N1 viruses to humans remains significant, given the continued occurrence of sporadic human cases (499 human cases in 15 countries) with a high case fatality rate (approximately 60%), the endemicity in poultry populations in several countries, and the potential for reassortment with the newly emerging 2009 H1N1 pandemic strain. Therefore, we review risk factors for H5N1 infection in humans. Methods and Findings Several epidemiologic studies have evaluated the risk factors associated with increased risk of H5N1 infection among humans who were exposed to H5N1 viruses. Our review shows that most H5N1 cases are attributed to exposure to sick poultry. Most cases are sporadic, while occasional limited human-to-human transmission occurs. The most commonly identified factors associated with H5N1 virus infection included exposure through contact with infected blood or bodily fluids of infected poultry via food preparation practices; touching and caring for infected poultry; consuming uncooked poultry products; exposure to H5N1 via swimming or bathing in potentially virus laden ponds; and exposure to H5N1 at live bird markets. Conclusions Research has demonstrated that despite frequent and widespread contact with poultry, transmission of the H5N1 virus from poultry to humans is rare. Available research has identified several risk factors that may be associated with infection including close direct contact with poultry and transmission via the environment. However, several important data gaps remain that limit our understanding of the epidemiology of H5N1 in humans. Although infection in humans with H5N1 remains rare, human cases continue to be reported and H5N1 is now considered endemic among poultry in parts of Asia and in Egypt, providing opportunities for additional human infections and for the acquisition of virus mutations that may lead to more efficient spread among humans and other mammalian species. Collaboration between human and animal health sectors for surveillance, case investigation, virus sharing, and risk assessment is essential to monitor for potential changes in circulating H5N1 viruses and in the epidemiology of H5N1 in order to provide the best possible chance for effective mitigation of the impact of H5N1 in both poultry and humans. Disclaimer The opinions expressed in this article are those of the authors and do not necessarily reflect those of the institutions or organizations with which they are affiliated.

A cohort study of health care workers to assess nosocomial transmissibility of Nipah virus, Malaysia, 1999

During 1998-1999, an outbreak of Nipah virus encephalitis occurred in Malaysia. To assess the possibility of nosocomial transmission, 338 health care workers (HCWs) exposed and 288 HCWs unexposed to outbreak-related patients were surveyed, and their serum samples were tested for anti-Nipah virus antibody. Needlestick injuries were reported by 12 (3%) HCWs, mucosal surface exposure to body fluids by 39 (11%), and skin exposure to body fluids by 89 (25%). No encephalitis occurred in either group. Three exposed and no unexposed HCWs tested positive by EIA for IgG antibodies. It is likely that these 3 were false positives; no IgM response occurred, and the serum samples were negative for anti-Nipah virus neutralizing antibodies. The risk of nosocomial transmission of Nipah virus appears to be low; however, given the high case-fatality rate and the presence of virus in respiratory secretions and urine of some patients, standard and droplet infection-control practices should be maintained with these patients.

Trends in hospitalizations associated with gastroenteritis among adults in the United States, 1979-1995

Gastroenteritis (GE) is among the most common illnesses of humans but the burden of disease, its epidemiology, and the distribution of pathogens in adults have not been fully examined. This information is needed to plan prevention strategies particularly for high-risk groups. This study is a retrospective analysis of data from the National Hospital Discharge Survey for the years 1979 through 1995 which describes the disease burden and epidemiology of hospitalizations associated with GE among adults in the United States. Diarrhoea was listed as a diagnosis on an average of 452,000 hospital discharges per year representing 1.5% of all hospitalizations among adults. The annual number of GE hospitalizations has decreased by 20% from approximately 500,000 in 1979 to 400,000 in 1995. The aetiology of 78% of cases coded as GE was undetermined. Until the aetiology of disease can be better established, specific strategies for prevention cannot be developed.

Review: interventions to increase influenza vaccination among healthcare workers in hospitals

Please cite this paper as: Hollmeyer et al. (2012) Review: interventions to increase influenza vaccination among healthcare workers in hospitals. Influenza and Other Respiratory Viruses 7(4), 604–621.

Seasonal influenza vaccine supply and target vaccinated population in China, 2004-2009.

To better understand the gap between limited influenza vaccine supply and the target population for vaccination in China, we conducted a retrospective survey to quantify the production capacity, supply and sale of seasonal trivalent inactive vaccine (TIV) from the 2004-2005 through the 2008-2009 season, and estimated the target population who should receive annual influenza vaccine. The maximum domestic capacity to produce TIV was 126 million doses in 2009. A total of 32.5 million doses of TIV were supplied in 2008-2009, with an average annual increase rate of 18% from 16.9 million in 2004-2005. This represents an amount sufficient to vaccinate 1.9% of Chinese population. The average number of doses of TIV for sale by province ranged from <5 to 108 per 1000 people. The differences are explained in part by level of economic development but also influenced by local reimbursement policies in some provinces. Based on national recommendations, we estimated a target population of 570.6 million or 43% of the total population. Supply and domestic production capacity for influenza vaccine is currently insufficient to vaccinate the estimated target population in China. The Government of China should consider measures to improve domestic production capacity of influenza vaccine, expand successful promotional campaigns, and add cost subsidies in high risk groups to further encourage influenza vaccine usage.