Low-cost UV lights halt TB spread

18 March 2009

The spread of tuberculosis, including drug-resistant strains, could be reduced by as much as 70 per cent simply through the use of ultraviolet lights, research part funded by the Wellcome Trust has revealed.

The study, by an international team of researchers, found that installing ultraviolet C lights in a hospital ward significantly reduced the rate of tuberculosis infection.

The low-cost measure could have significant benefits in developing countries, which suffer the highest burden of the disease.

Tuberculosis infects more than nine million people a year, with almost two million deaths, according to the World Health Organisation. Coughing patients can easily spread the disease through the air, but the bacteria can be killed by ultraviolet C light, which is safe to humans at low intensities.

The researchers installed shielded ultraviolet lights and fans to help circulate the air in the ceiling of a tuberculosis ward in Lima, Peru. For 18 months, air from the ward was pumped to three groups of guinea pig patients who received either air exposed to the ultraviolet lights, or air treated with an ioniser or untreated air.

Tests revealed that just 29 in the ultraviolet guinea pig group were infected with tuberculosis, compared with 43 in the ioniser group and 106 in the untreated air group.

The team's previous research had shown that opening windows could reduce tuberculosis transmission, but this cannot work everywhere.

"You can't open the windows in a Siberian hospital, for example," said lead researcher Dr Rod Escombe from the Wellcome Trust Centre for Clinical Tropical Medicine at Imperial College London.

Dr Escombe said the use of cheap ultraviolet lights could be particularly beneficial to the developing world.

"People are more likely to die from the disease in developing countries like Peru, because there are limited resources for isolating patients, diagnosing them quickly and starting effective treatment. Also, the prevalence of drug-resistant tuberculosis is much higher in the developing world. Preventing infection is much easier and cheaper than treating a patient with tuberculosis."

The lights cost around $350 and the researchers are now looking at ways to develop new units costing just $100.

Image credit: Flickr/musicalwds

Reference

Escombe AR et al. Upper-room ultraviolet light and negative air ionization to prevent tuberculosis transmission, PLoS Medicine, 17 March 2009.