May 18, 2011

Face Masks Could Prevent Spread of TB

(Ivanhoe Newswire) "“ Patients with tuberculosis (TB) who wear a simple facemask may be able to greatly cut transmission rates to non-infected patients, according to a study conducted on guinea pigs.

"We found that when infectious patients with multidrug resistant tuberculosis (MDR-TB) wore face masks while they were hospitalized, the face masks helped decrease the transmission of tuberculosis by 50 percent compared to when the patients did not wear face masks," study author Ashwin Dharmadhikari, MD, associate physician at Harvard Medical School's Brigham &Women's Hospital was quoted as saying. "Simply put, face masks were able to cut tuberculosis transmission in half."

The masks may represent a simple way to reduce TB transmissions in areas with limited resources and widespread TB.

During the three-month study period, a series of 17 adult TB patients occupied the Airborne Infections Research Facility ward at the Mpumalanga Provincial MDR-TB Referral Hospital in Emalahleni, South Africa. Each patient occupied the ward for 3 weeks before being replaced and was encouraged and monitored to make sure face masks were worn for 12-hour periods on alternate days. Masks were removed during mealtimes and to allow patients to take medications.

A mechanical ventilation system exhausted all ward air on alternating days to each of two identical exposure chambers holding 180 healthy guinea pigs equally divided into an intervention group and a control group. Skin tests to monitor for tuberculosis infection were administered to the guinea pigs at the beginning of the study and monthly during the study. Intervention group animals only breathed ward air during periods when patients wore surgical face masks, and control animals only breathed ward air during periods when patients did not wear any masks. At the end of the study, efficacy was determined by comparing the incidence of infection among animals in each chamber.

Guinea pigs in the control group had more than twice the risk of becoming infected compared to guinea pigs in the intervention group. In the control group, 69 animals (76 percent) became infected. In the intervention group, 36 animals (40 percent) became infected.

"These findings provide evidence on methods that could be used for TB control," Dr. Dharmadhikari said."They may also help health care facilities and other stakeholders involved in TB control decide on how suitable this intervention is for protecting individuals against TB infection in the environments in which they work."

"In those settings, it may be possible to encourage patients to wear masks while they are getting worked up for TB, so that the chances of healthcare workers or other patients getting TB are reduced," Dr. Dharmadhikari said.

SOURCE: ATS 2011 International Conference., Denver, CO, May 13, 2011