Ultraviolet Lights Could Reduce TB Spread in Hospitals, Study Says

Installing ultraviolet-C, or UVC, lights and air flow systems could reduce the spread of tuberculosis in hospitals and waiting rooms by 70%, according to a study published Tuesday in the journal PLoS Medicine, BBC News reports. When someone with TB coughs, bacteria disperse in the air in tiny droplets, which can cause people in the surrounding area to contract the disease. According to study author Rod Escombe of Imperial College London, "When people are crowded together in a hospital waiting room, it may take just one cough to infect several vulnerable patients."

UVC lights kill TB bacteria -- including drug-resistant strains -- by damaging their DNA so the bacteria cannot grow, divide or be transmitted to other people. According to BBC News, the technology already is used to disinfect empty ambulances and emergency rooms, and health officials have begun plans to install UVC lights in the chest clinic at St. Mary's Hospital in London, which will be the first U.K. hospital with the technology.

For the study, Escombe and colleagues hung UVC lights in a hospital ward in Lima, Peru, where 69 patients were receiving treatment for HIV/TB coinfection. The researchers also studied guinea pigs in an enclosure on the hospital roof for 535 consecutive days and pumped different types of air to three groups of animals. One group of guinea pigs received air exposed to the UVC lights, one group received air treated with negative ionizers and the third group received untreated air directly from the HIV/TB ward. Of the animals exposed to the UVC-treated air, 9.5% contracted TB and 3.6% developed the active form of the disease, the researchers found. Of the animals exposed to the untreated air, 35% contracted TB and 8.6% developed the active disease, according to the study (BBC News, 3/17). The researchers also reported that 14% of the animals receiving the ionized air contracted TB (AFP/Google.com, 3/17).

According to Escombe, previous research has demonstrated that opening windows can reduce the spread of TB in a room. However, this intervention is "climate dependent -- you can't open the windows in the intensive care ward of a Siberian hospital, for example," he said. According to Escombe, developing countries often face a high TB burden, which can be further complicated by high rates of drug-resistant TB and limited resources for patient isolation. However, installing UVC lights could be a relatively low-cost intervention for controlling the spread of the disease. According to BBC News, UVC ceiling lights cost about $350 and replacement bulbs cost about $25 (BBC News, 3/17). According to Escombe, "Preventing infection is much easier and cheaper than treating a patient with TB." Researcher Cath Noakes of the University of Leeds Faculty of Engineering added that health centers should pair the UVC lights with effective air flow systems. Noakes said UVC lights "must be set high enough to ensure patients and health workers are not overexposed, but if the lights only treat air at that level, there will be little benefit." According to Noakes, "To be most effective, ventilation systems need to create a constant flow of treated air down to patient level, and potentially infected air up to the lights" (Daily Telegraph, 3/17).

The study is available online.