'Hot Tub Lung' May Befall
Users of Dirty Hot Tubs

NEW YORK (Reuters Health) - The cases of two women with "hot tub lung" recently described by Mayo Clinic researchers reveal the potential dangers of using a hot tub without cleaning it regularly.

The two women had respiratory illness that was eventually traced to bacteria growing in their home hot tubs. In both cases, the illness was likely not due to infection with Mycobacterium avium complex (MAC) bacteria, but to hypersensitivity to the infectious agent, according to Dr. Otis Rickman and colleagues in Rochester, Minnesota.

The researchers describe the cases of the women, aged 45 and 50, in the November issue of Mayo Clinic Proceedings.

Each woman had come to the Mayo Clinic seeking a second opinion on their condition. Both were being treated with corticosteroids based on their original diagnosis, which was not helping their lung function. Their respiratory symptoms and lung function progressively worsened, and computed tomography scans of their lungs revealed signs of damage.

Both women reported frequently using their home hot tubs, the report indicates.

Tests by the Mayo Clinic team revealed the presence of MAC in each of the women's hot tubs. The women were instructed to drain and clean the tubs and stop using them, which led to speedy improvement of their respiratory symptoms and lung function. The abnormalities seen on scans of their lungs also disappeared. Neither woman was given drug therapy against the bacteria.

Hot tubs that are not routinely cleaned provide an excellent breeding ground for the bacteria, the authors note. Many users may not realize that at water temperatures above 84 degrees Fahrenheit chlorine loses much of its disinfectant ability, they point out. And bubbles and steam arising from heated water carry MAC, making it easy to inhale.

Although most healthy adults can fend off an infection with the bug, experts say that pulmonary MAC infections usually occur in persons with immunodeficiency or chronic lung disease. But both women seemed to be sickened by hypersensitivity to the bacterium, rather than infection with it.

Although the results are inconclusive, Rickman and his team believe that exposure to mycobacteria present in the hot tub water led to inflammation of the women's lungs.

"Of note, all the cases of hot tub lung reported in the literature have been associated with a hot tub indoors at a personal residence," the authors write.

"We recommend that physicians maintain a high index of suspicion for hot tub lung and include questions about hot tub use in their routine review of symptoms in patients with respiratory problems," Rickman said in a prepared statement.

SOURCE: Mayo Clinic Proceedings 2002;77:1233-1237.

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