Absence of detectable influenza RNA transmitted via aerosol during various human respiratory activities--experiments from Singapore and Hong Kong

Two independent studies by two separate research teams (from Hong Kong and Singapore) failed to detect any influenza RNA landing on, or inhaled by, a life-like, human manikin target, after exposure to naturally influenza-infected volunteers. For the Hong Kong experiments, 9 influenza-infected volunt...

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Bibliographic Details
Published in:PloS one 2014-09, Vol.9 (9), p.e107338-e107338
Main Authors: Tang, Julian W, Gao, Caroline X, Cowling, Benjamin J, Koh, Gerald C, Chu, Daniel, Heilbronn, Cherie, Lloyd, Belinda, Pantelic, Jovan, Nicolle, Andre D, Klettner, Christian A, Peiris, J S Malik, Sekhar, Chandra, Cheong, David K W, Tham, Kwok Wai, Koay, Evelyn S C, Tsui, Wendy, Kwong, Alfred, Chan, Kitty, Li, Yuguo
Format: Article
Language:English
Subjects:
Adolescent
Adult
Aerosols
Air samples
Air sampling
Alcohol
Alcohols
Assaying
Biology and Life Sciences
Breathing
Cough
Counting
Diagnostic systems
DNA-directed RNA polymerase
Exhalation
Exposure
Female
Filters
Health aspects
Hong Kong
Hospitals
Humans
Infections
Influenza
Influenza A
Influenza A Virus, H1N1 Subtype - genetics
Influenza A Virus, H3N2 Subtype - genetics
Influenza B virus - genetics
Influenza, Human - transmission
Influenza, Human - virology
Laboratories
Male
Mechanical engineering
Medical research
Medicine
Medicine and Health Sciences
Middle Aged
Models, Anatomic
Mouth
Nose
Polymerase chain reaction
Polytetrafluoroethylene
Public health
Respiration
Ribonucleic acid
RNA
RNA, Viral - genetics
RNA, Viral - isolation & purification
Singapore
Studies
Swine flu
Viral Load
Viruses
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Summary:Two independent studies by two separate research teams (from Hong Kong and Singapore) failed to detect any influenza RNA landing on, or inhaled by, a life-like, human manikin target, after exposure to naturally influenza-infected volunteers. For the Hong Kong experiments, 9 influenza-infected volunteers were recruited to breathe, talk/count and cough, from 0.1 m and 0.5 m distance, onto a mouth-breathing manikin. Aerosolised droplets exhaled from the volunteers and entering the manikin's mouth were collected with PTFE filters and an aerosol sampler, in separate experiments. Virus detection was performed using an in-house influenza RNA reverse-transcription polymerase chain reaction (RT-PCR) assay. No influenza RNA was detected from any of the PTFE filters or air samples. For the Singapore experiments, 6 influenza-infected volunteers were asked to breathe (nasal/mouth breathing), talk (counting in English/second language), cough (from 1 m/0.1 m away) and laugh, onto a thermal, breathing manikin. The manikin's face was swabbed at specific points (around both eyes, the nostrils and the mouth) before and after exposure to each of these respiratory activities, and was cleaned between each activity with medical grade alcohol swabs. Shadowgraph imaging was used to record the generation of these respiratory aerosols from the infected volunteers and their impact onto the target manikin. No influenza RNA was detected from any of these swabs with either team's in-house diagnostic influenza assays. All the influenza-infected volunteers had diagnostic swabs taken at recruitment that confirmed influenza (A/H1, A/H3 or B) infection with high viral loads, ranging from 10(5)-10(8) copies/mL (Hong Kong volunteers/assay) and 10(4)-10(7) copies/mL influenza viral RNA (Singapore volunteers/assay). These findings suggest that influenza RNA may not be readily transmitted from naturally-infected human source to susceptible recipients via these natural respiratory activities, within these exposure time-frames. Various reasons are discussed in an attempt to explain these findings.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0107338