Testing Interventions to Human-Generated Occupational Airborne Infections

Details

• Personal Author:
  Dharmadhikari A ; Jensen P ; Mphahlele M ; Nardell EA ; van der Walt M
• Description:
  Background: This project aimed to test interventions to reduce the risk of airborne infection to workers. We used patients with multidrug resistant tuberculosis (MDR-TB) for our study because airborne person to person transmission is substantially the same for all infections with airborne potential, including SARS and influenza. Methods: Our study site was the already established Airborne Infections Research (AIR) Facility, adjacent to a regional MDR-TB referral center, Mpumalanga, South Africa, to test 3 conventional interventions of interest: 1) upper room ultraviolet germicidal irradiation (UVGI), 2) room filtration air cleaners; and 3) surgical masks on patients. In this unique facility, guinea pigs breathing exhaust air from the clinical ward serve as quantitative air samplers for transmission from TB patients. The experimental plan was similar for all 3 interventions tested. For each of 5 experiments of 2-3 month total exposure, a series of 15-27 consenting, newly admitted infectious patients with MDR-TB served for periods of 2 to 4 weeks each to expose180 healthy guinea pigs. The guinea pigs were divided into two identical exposure chambers, each receiving equal exhaust air from the AIR facility on alternating days. The intervention being tested on the ward was also applied on alternate days, with exhaust air being delivered to one guinea pig chamber (intervention chamber) on the days the intervention was on in the patient rooms; and to the control exposure chamber on the days when the intervention was off. The difference in infection rate between the two chambers directly measured the effectiveness of the intervention for the entire patient cohort. Results: 1) UVGI was found to be 80% effective with a ceiling fan providing good air mixing; 2) Room air filtration machines delivering (clean air delivery rate, CADR) of approximately 15 room air changes per hour (ACH) reduced the risk of infection by an estimated 20%, but this was not statistically significant; and 3) Surgical masks on patients were 53% effective in reducing infection of the guinea pigs. Another highly important but unanticipated observation made during these studies was that in the non intervention arm, transmission varied greatly from study to study depending on the presence or absence of patients among the cohort with undiagnosed extensively drug resistant TB (XDR-TB) who were inadequately treated with the standard South African treatment for MDR-TB. Conclusions: This study: 1) confirmed that UVGI with ceiling fans can be highly effective under real world conditions, 2) that room air filtration machines were surprisingly ineffective under the same conditions, and 3) for the first time, that surgical face masks on patients were 53% effective in preventing transmission. Finally, and perhaps most importantly for global TB control efforts, these studies demonstrated that effective MDR treatment rapidly and markedly inhibited transmission from MDR patients, but not from unsuspected XDR patients. The latter observation will have important implications for the safety of MDR treatment in hospitals, clinics, and in the community. All of these results will impact on the protection of workers in the US and around the world for years to come. [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Communicable Diseases Environmental Monitoring Occupational Health Personal Protective Equipment Respiratory Protective Devices Safety Tuberculosis Ventilation
• Keywords:
  Airborne Particles Air Monitoring Air Purifiers Air Treatment Equipment Bacteria Bacterial Disease Contagious Diseases Disease Transmission Germicides Infection Control Infection Prevention Infectious Agents Infectious Diseases MDROs Multidrug Resistant Organisms Mycobacterium Surgical Masks TB Ultraviolet Radiation Ventilation Systems

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• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  Massachusetts ; OSHA Region 1
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-28
• NIOSHTIC Number:
  nn:20052551
• NTIS Accession Number:
  PB2018-101546
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-009050, 2012 Apr; :1-28
• Contact Point Address:
  Edward A. Nardell, MD, Associate Professor, Brigham and Women's Hospital, Division of Global Health Equity, 641 Huntington Avenue, 3A-03, Boston, MA 02115
• Email:
  enardell@pih.org
• Federal Fiscal Year:
  2012
• NORA Priority Area:
  Healthcare and Social Assistance
• Performing Organization:
  Brigham and Women's Hospital, Boston, Massachusetts
• Peer Reviewed:
  False
• Start Date:
  20060801
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20170731
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:12e7e9157dd58e2e62aa6d7df531c35cb090ec6717f7bb2fb16a1b75f49a0838e3895640b0950e47409f0e0f7c519d1bcdc8c36be786820d6723d748766daf73
• Download URL:
  https://stacks.cdc.gov/view/cdc/218710/cdc_218710_DS1.pdf
• File Type:
  [PDF - 605.93 KB ]