Ultraviolet light reduces spread of TB

17 March 2009

Ultraviolet lights could reduce the spread of tuberculosis in hospital wards and waiting rooms by 70 per cent, says a new study, Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission published in PLoS Medicine today.

The study, which explored the transmission of tuberculosis (TB) from infected patients to guinea pigs, suggests that installing simple ultraviolet C (UVC) lights in hospitals could help reduce the transmission of TB, including drug-resistant strains.

UVC light is very damaging to tuberculosis bacteria, including multi- and extensively drug-resistant strains, but is safe to humans in the low intensities that reach the lower part of the room where occupants are. Overexposure causes a sunburn-like effect on the skin and can irritate the eyes, but reactions only last 24 hours.

Every year, over nine million people are infected with tuberculosis and nearly two million people die from the disease, according to the World Health Organisation. Infection rates are particularly high in places where vulnerable people are crowded together, such as hospitals, homeless shelters and prisons.

There are two types of TB infection - latent and active. Patients with active TB experience the symptoms of the disease, which include fever, persistent cough, and loss of appetite, and these patients can transmit the disease by coughing. In contrast patients with the dormant, 'latent' form of TB do not have symptoms, and are not infectious.

About 10 per cent of latent TB patients develop active TB over their lifetimes (although this figure rises to over 40 per cent if they have HIV infection as well). Treatment can prevent many patients with latent TB from progressing to active TB. About 95 per cent of TB patients with drug-sensitive disease can be cured with antibiotics, but this figure is much lower in patients with drug-resistant TB disease.