Evaluating Modes of Influenza Transmission Observational Study of Community Acquired Influenza (EMIT)
The recent swine origin influenza pandemic (2009), new emergence of swine origin H3N2v, and delayed availability of vaccine for these agents highlight the need to test and optimize public health intervention strategies to reduce transmission of influenza. We will use a new technology for biological particle collection (U.S. Provisional Patent Application No. 61/162,395, McDevitt et al., Aerosol Sci Technol 2013) to make fundamental observations on infectious respiratory droplets in a study of up to 200 naturally occurring seasonal influenza cases. We will collect respiratory droplets shed by participants while breathing normally, talking, and spontaneously coughing. We will characterize the size distribution of droplets containing infectious virus. We will use these basic data to examine the roles of large and small respiratory droplets and examine how the interaction of host factors and virus type impact the shedding of infectious respiratory droplets. Subjects will be recruited through a web based respiratory illness surveillance system, health clinics and advertisement in the campus community. Sitting in the collection booth will not create additional discomfort or risk for volunteers already suffering from influenza infection. We will recruit up to 1000 persons with symptoms of acute respiratory illness for screening with collection of nasopharyngeal swabs and questionnaire. From among those screened, we will recruit 250 to give exhaled breath samples, and ask 50 people with influenza to return for follow up exhaled breath samples on up to two subsequent days. We hypothesize that (1) fine aerosols (<5 microns in aerodynamic diameter) will contain more viral copies than coarse aerosol particles (>= 5 microns) (2) fine aerosols will contain culturable virus indicating that the fine aerosols are infectious, (3) aerosol shedding will correlate with virus load measured by swabs, (4) presence of active cough during sampling will be associated with increased aerosol shedding, (5) clinical symptoms and signs, including fever can be used to predict viral aerosol shedding.
Influenza Virus Infection Transmission in Humans
|Study Design:||Observational Model: Case-Only
Time Perspective: Cross-Sectional
|Official Title:||Evaluating Modes of Influenza Transmission Work Package 1: Observational Study of Community Acquired Influenza|
- Viral copy number in exhaled breath aerosol coarse and fine particle fractions [ Time Frame: At enrollment and over 2 days follow-up ] [ Designated as safety issue: No ]Participants will sit for 30 minutes with their face inside the cone/funnel of the Gesundheit-II (G-II)human bioaerosol collector (McDevitt JJ et al. Aerosol Sci Technol 2013, in press). Subjects are free to tidal breathe, cough, and talking. A conventional slit impactor collects particles > 5.0 μm. Condensation of water vapor is used to grow remaining particles for efficient collection by a 1.0 μm slit impactor and be deposited into a buffer-containing collector. Samples are assayed by RT-PCR and viral culture. The method was previously used to assess effectiveness of surgical masks for containing influenza virus aerosols (Milton DK, et al. PLoS Pathogens 2013, in press).
- Correlation of exhaled particle counts and viral copy numbers [ Time Frame: At enrollment and over 2 days follow-up ] [ Designated as safety issue: No ]Hypothesis: exhaled particle numbers counted with an optical particle counter (Exhalair, Pulmatrix, Inc, Lexington, MA) during tidal breathing will correlate with exhaled viral copy numbers, especially in the fine particle fraction
- Impact of multiple infection [ Time Frame: At enrollment and over 2 days of follow-up ] [ Designated as safety issue: No ]Hypothesis: co-infection with other respiratory agents will increase aerosol production
- Correlation of exhaled virus in community acquired and experimental infection [ Time Frame: At enrollment and up to 2 days of follow-up ] [ Designated as safety issue: No ]These data will be used to compare subjects with community acquired influenza with donor subjects artificially infected with influenza in EMIT-Work Package 3 and with recipient subjects exposed the the donors. We will test the hypothesis that the donor subjects in EMIT-WP3 produce similar amounts of viral aerosol as do community acquired infection cases. We will also examine whether recipients exposed only to aerosols differ from those exposed by contact and large droplet as well as aerosol routes with respect to exhaled aerosol virus.
- RSV and other respiratory infections [ Time Frame: At enrollment ] [ Designated as safety issue: No ]Hypothesis: RSV and cases with other respiratory infections who are not infected with influenza will have the infecting agent present in exhaled breath aerosols
Biospecimen Retention: Samples With DNA
viral cultures, viral RNA, viral cDNA, NP swabs, exhaled breath particles
|Study Start Date:||December 2012|
|Study Completion Date:||March 2013|
|Primary Completion Date:||March 2013 (Final data collection date for primary outcome measure)|
Community acquired respiratory infection
Measurement of exhaled breath aerosol
This study is a follow-on to earlier projects funded by the US Centers for Disease Control and Prevention (CDC) and the National Institute for Allergy and Infectious Diseases (NIAID) that developed the sampler and studied the impact of surgical masks on reducing viral aerosol release by persons infected with influenza virus. The funding organizations have no direct control over the study design, execution, or reporting and no access to identifiable human data. The CDC IRB has determined that the CDC is not engaged in human subjects research in this cooperative agreement.
- Fine particle aerosols will contain greater numbers of viral copies than will coarse aerosol particles.
- Clinical symptoms and signs, including fever can be used to predict viral aerosol shedding
- Fine aerosols will contain culturable virus indicating that the fine aerosols are infectious
- Aerosol shedding will correlate with virus load measured by nasopharyngeal and throat swabs
- Presence of active cough during sampling will be associated with increased aerosol shedding with a stronger correlation to be found with coarse than fine particle virus aerosols
|United States, Maryland|
|University of Maryland School of Public Health|
|College Park, Maryland, United States, 20742|
|Principal Investigator:||Donald K Milton, MD, DrPH||University of Maryland|