TB Infection Control

Thanks for calling this BBC story covering the publication of Rod Escombe's groundbreaking research to the attention of the group. I will post the entire article today. Rod exposed hundreds of normal highly vulnerable sentinel guinea pigs to the air from a TB/HIV ward at Dos De Mayo Hospital in Lima, Peru. Upper room UV fixtures in the ward were turned on every other day, and every other day the exhaust air from the ward was directed to one of the two guinea pig exposure chambers. At
the end of the perfectly controlled study, the two guinea pig chambers had been exposed to exactly the same exhaust air, the only difference being the UV air disinfection being turned on every other day. The difference in the infection rate between the two guinea pig exposure
chambers accurately reflects the protection provided by the upper room UV light. That protection was an impressive 72% (my recollection -paper not in front of me).

In South Africa a consortium of researchers including the SA MRC, the US CDC, and Harvard University has just completed a similar experiment and also found extremely high levels of protection, 100% (exact CI 62.5 - 100%). This ...

Thanks for calling this BBC story covering the publication of Rod Escombe's groundbreaking research to the attention of the group. I will post the entire article today. Rod exposed hundreds of normal highly vulnerable sentinel guinea pigs to the air from a TB/HIV ward at Dos De Mayo Hospital in Lima, Peru. Upper room UV fixtures in the ward were turned on every other day, and every other day the exhaust air from the ward was directed to one of the two guinea pig exposure chambers. At
the end of the perfectly controlled study, the two guinea pig chambers had been exposed to exactly the same exhaust air, the only difference being the UV air disinfection being turned on every other day. The difference in the infection rate between the two guinea pig exposure
chambers accurately reflects the protection provided by the upper room UV light. That protection was an impressive 72% (my recollection -paper not in front of me).

In South Africa a consortium of researchers including the SA MRC, the US CDC, and Harvard University has just completed a similar experiment and also found extremely high levels of protection, 100% (exact CI 62.5 - 100%). This study will be repeated shortly with some variations.

Both of these studies provide the most direct evidence to date that properly designed, installed, and maintained upper room UV systems, including room air mixing, can be a major intervention for preventing TB transmission under conditions existent under low resource, high prevalence conditions. Along with thoughtful building design and usage, natural ventilation, extraction fans, and mechanical ventilation systems, UV provides a useful option or supplement to air disinfection under high risk conditions.

Edward A. Nardell, M.D.
Associate Professor
Harvard Medical School (Medicine; Global Health and Social Medicine)
Harvard School of Public Health (Environmental Health; Immunology and
Infectious Diseases)

Brigham and Women's Hospital
Divisions of Global Health Equity and Pulmonary Medicine
FXB Building, 709c
651 Huntington Ave.
Boston, MA 02115

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You may be interested to hear that we have a new research project on UVGI commencing shortly at Leeds University in the UK. It will be a three year study based on mathematical modelling to evaluate how UV lights interact with the airflow and where such lights should best be used in different healthcare environments. Now we have direct and up-to-date evidence from Peru and South Africa on the real world efficacy of this technology, understanding how and where it should be applied is an essential next step for acceptance as a widely recognised environmental control technique. This is particularly important in naturally ventilated spaces, where lamps can never be challenged with bioaerosols to quantify effectiveness for safety reasons. As we clearly can't place guinea pigs on every ward, using airflow models with UV data from controlled lab experiments is the next best thing in terms of predicting performance.

Dr Cath Noakes
Institute of Pathogen Control Engineering
School of Civil Engineering
University of Leeds