AIDSWEEKLY Plus; Monday, July 6, 2009
Staff Medical Writers

NewsRx --

2009 JUL 6 - (NewsRx.com) -- According to recent research from London, the United Kingdom, " Institutional tuberculosis (TB) transmission is an important public health problem highlighted by the HIV/AIDS pandemic and the emergence of multidrug- and extensively drug-resistant TB. Effective TB infection control measures are urgently needed."

"We evaluated the efficacy of upper-room ultraviolet (UV) lights and negative air ionization for preventing airborne TB transmission using a guinea pig air-sampling model to measure the TB infectiousness of ward air. Methods and Findings For 535 consecutive days, exhaust air from an HIV-TB ward in Lima, Peru, was passed through three guinea pig air-sampling enclosures each housing approximately 150 guinea pigs, using a 2-d cycle. On UV-off days, ward air passed in parallel through a control animal enclosure and a similar enclosure containing negative ionizers.

On UV-on days, UV lights and mixing fans were turned on in the ward, and a third animal enclosure alone received ward air. TB infection in guinea pigs was defined by monthly tuberculin skin tests. All guinea pigs underwent autopsy to test for TB disease, defined by characteristic autopsy changes or by the culture of Mycobacterium tuberculosis from organs. 35% (106/304) of guinea pigs in the control group developed TB infection, and this was reduced to 14% (43/303) by ionizers, and to 9.5% (29/307) by UV lights (both p<0.0001 compared with the control group).

TB disease was confirmed in 8.6% (26/304) of control group animals, and this was reduced to 4.3% (13/303) by ionizers, and to 3.6% (11/307) by UV lights (both p<0.03 compared with the control group). Time-to-event analysis demonstrated that TB infection was prevented by ionizers (log-rank 27; p<0.0001) and by UV lights (log-rank 46; p<0.0001). Time-to-event analysis also demonstrated that TB disease was prevented by ionizers (log-rank 3.7; p=0.055) and by UV lights (log-rank 5.4; p=0.02).

An alternative analysis using an airborne infection model demonstrated that ionizers prevented 60% of TB infection and 51% of TB disease, and that UV lights prevented 70% of TB infection and 54% of TB disease. In all analysis strategies, UV lights tended to be more protective than ionizers. Upper-room UV lights and negative air ionization each prevented most airborne TB transmission detectable by guinea pig air sampling," wrote A.R. Escombe and colleagues, University of London, Imperial College (see also HIV/AIDS Co-Infection).

The researchers concluded: "Provided there is adequate mixing of room air, upper-room UV light is an effective, low-cost intervention for use in TB infection control in high-risk clinical settings."

Escombe and colleagues published their study in Plos Medicine (Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission. PLoS Med. 2009 Mar 17;6(3):e43.

For additional information, contact A.R. Escombe, University of London Imperial College, Dept. of Infectious Disease & Immun, London, UK.

Publisher contact information for the journal Plos Medicine is: Public Library Science, 185 Berry St., Ste. 1300, San Francisco, CA 94107, USA.

Keywords: United Kingdom, London, HIV/AIDS Co-Infection, AIDS, Acquired Immunodeficiency Syndrome, Autopsy, Clinical Trial Research, Cutaneous Tuberculosis, Drug Development, HIV, Human Immunodeficiency Virus Bacterial Infection, Infectious Disease, Mycobacteria, Mycobacterium Tuberculosis, Pandemics, Public Health, Surgery, Therapy, Treatment, Virology, University of London, Imperial College.

This article was prepared by AIDS Weekly editors from staff and other reports.

2009-07-06
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