Institutional Tuberculosis Transmission. Controlled Trial of Upper Room Ultraviolet Air Disinfection: A Basis for New Dosing Guidelines.
BACKGROUND
Transmission is driving the global tuberculosis epidemic, especially in congregate settings. Worldwide, natural ventilation is the most common means of air disinfection, but it is inherently unreliable and of limited use in cold climates. Upper room germicidal ultraviolet (UV) air disinfection with air mixing has been shown to be highly effective, but improved evidence-based dosing guidelines are needed.


OBJECTIVE
To test the efficacy of upper room germicidal air disinfection with air mixing to reduce tuberculosis transmission under real hospital conditions, and to define the application parameters responsible as a basis for proposed new dosing guidelines.


METHODS
Over an exposure period of 7 months, 90 guinea pigs breathed only untreated exhaust ward air, and another 90 guinea pigs breathed only air from the same six-bed tuberculosis ward on alternate days when upper room germicidal air disinfection was turned on throughout the ward.


RESULTS
The tuberculin skin test conversion rates (>6 mm) of the two chambers were compared. The hazard ratio for guinea pigs in the control chamber converting their skin test to positive was 4.9 (95% confidence interval, 2.8-8.6), with an efficacy of approximately 80%.


CONCLUSIONS
Upper room germicidal UV air disinfection with air mixing was highly effective in reducing tuberculosis transmission under hospital conditions. These data support using either a total fixture output (rather than electrical or UV lamp wattage) of 15-20 mW/m(3) total room volume, or an average whole-room UV irradiance (fluence rate) of 5-7 μW/cm(2), calculated by a lighting computer-assisted design program modified for UV use.
1 MDR-TB Program, JHPIEGO, Pretoria, South Africa.
Matsie
M
Mphaphlele
2 Division of Pulmonary and Critical Care Medicine and.
Ashwin S
AS
Dharmadhikari
3 CDC Division of Tuberculosis Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Atlanta, Georgia.
Paul A
PA
Jensen
4 Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts.
Stephen N
SN
Rudnick
5 Council for Scientific and Industrial Research, Pretoria, South Africa.
Tobias H
TH
van Reenen
6 Harvard School of Public Health, Boston, Massachusetts.
Marcello A
MA
Pagano
7 Department of Electronic and Computer Engineering, University of Pretoria, Pretoria, South Africa.
Wilhelm
W
Leuschner
8 Acuity Brands Lighting, Connors, Georgia.
Tim A
TA
Sears
4 Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts.
Sonya P
SP
Milonova
9 Medical Research Council, Pretoria, South Africa.
Martie
M
van der Walt
10 Division of Infectious Diseases, Internal Medicine, University of Pretoria Medical School, Pretoria, South Africa; and.
Anton C
AC
Stoltz
11 Global Tuberculosis Programme, World Health Organization, Geneva, Switzerland.
Karin
K
Weyer
2 Division of Pulmonary and Critical Care Medicine and.|12 Division of Global Health Equity, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Edward A
http://orcid.org/0000-0002-5323-3196
EA
Nardell
D000818:Animals; D004203:Disinfection; D006168:Guinea Pigs; D017053:Infection Control / Q000379:methods*; D014374:Tuberculin Test; D014376:Tuberculosis / Q000517:prevention & control* / Q000635:transmission*; D014466:Ultraviolet Rays; D014691:Ventilation
air disinfection; infection control; tuberculosis prevention; tuberculosis transmission; ultraviolet irradiation