Legionnaire disease is an infection that is usually caused by air-conditioning systems, hot-water systems, spas and fountains that are not properly cleaned or maintained. On Friday, doctors reported the first known case of Legionnaire disease caused by a visit to the dentist office in Rome.
An 83-year old woman died after she contracted the Legionnaires’ disease from her dentist’s water. She contracted the disease in February of 2011, but in the time of the disease’s incubation period, she only left her house twice and that was to visit the dentist. She was taken to the G.B. Morgagni-Pierantoni Hospital in Forlì, Italy after suffering breathing problems and a high temperature. She was quickly diagnosed with Legionnaire’s disease and given a high dose of antibiotics, but died two days later.
When scientists tested the water line, they discovered the Legionella pneumophila bacteria. In the case report in Lancet the authors write, “L. pneumophila is a gram-negative bacterium ubiquitous in natural water environments and found also in man-made water systems. It can infect people by inhalation or micro-aspiration of aerosolized water causing a severe pneumonia known as Legionnaires’ disease, mainly affecting elderly and immune-compromised patients, or a flu-like disease, known as Pontiac fever.”
“However, as far as we are aware, no case of Legionnaires’ disease has been associated with this source of infection. The case here shows that the disease can be acquired from a dental unit waterline during routine dental treatment. Aerosolised water from high-speed turbine instruments was most likely the source of the infection. Legionella contamination in dental unit waterlines must be minimised to prevent exposure of patients and staff to the bacterium.”
It’s unclear what kind of standards are in place for the water lines in Italy compared to the United States. The American Dental Association (ADA) recommends that dental water lines contain no more than 500 colony-forming units of bacteria per milliliter of water, the same limit recommended by the U.S. Centers for Disease Control and Prevention.
The authors of the case study suggest a few control measures anyway. “We suggest several control measures: use of anti-stagnation and continuous-circulation water systems; use of sterile water instead of the main water supply in the dental unit waterline; application of discontinuous or continuous disinfecting treatment; daily flushing of all outlets and before each dental treatment; use of filters upstream of the instruments; and annual monitoring of the waterline.”