Medicine: Swimming-Pool Elbow

When the 37-year-old woman who ran a pet shop in a Los Angeles suburb cut her right middle finger on the metal rim of a tropical-fish tank, she thought nothing of it. The cut seemed to be clean, and it healed quickly. But within a month, abscesses formed under the skin on the back of her finger and hand. They were not painful, but they were unsightly, and occasionally one of them burst and oozed a sticky fluid until a new scab formed. The woman's 18-year-old son cut his finger on the same tank,...