“What’s this?” Bernstein asked, pointing to a red lesion on the side of the patient’s thumb. The patient had burned it a couple of months earlier, and it had been healing very slowly. It became infected and took two rounds of antibiotics to start to clear up.
Bernstein reviewed the tests obtained by Vitale. All the blood tests were normal. And the imaging showed only the swelling and fluid around the tendons and joint. This could be an inflammatory arthritis; there were some that didn’t show up in blood tests. But seeing that lesion got Bernstein worrying that it could be an infection. And there was one infection that she was particularly concerned about.
“Have you cleaned a fish lately?” the doctor asked. The question surprised the patient. Yes, she had. Months earlier, before all this had started, her daughter had ordered three branzinos from the market. Normally the patient’s husband, an avid fisherman, would have cleaned them, but he had just had shoulder surgery. So he coached from the sidelines as she scaled and cleaned them. It was a mess. By the time she was done, there were fish scales and drops of her blood everywhere. But the fish cooked just beautifully.
Bernstein nodded. Around the patient’s thumb were several tiny bumps that seemed to line up going from the tip of her thumb toward her wrist. Bernstein recognized this as a sign of a rare infection, caught from fish — often while scaling them. Indeed, this infection, caused by a cousin of tuberculosis, mycobacterium marinum (M.M.), is sometimes called fish handlers’ disease. Bernstein had seen it once before, years earlier. The organism enters the body through a cut or scrape in the skin. Once in, it grows slowly, then travels the body by way of the lymphatic system, which is why the disease’s characteristic nodules and ulcers often appear in the lines formed by the underlying lymph vessels. Bernstein suspected that the infection in the thumb had spread to the patient’s hand and wrist — and that the steroids the patient took contributed to the infection’s atypical swelling rather than the usual nodules.
Still, this was a rare disease; there were maybe three cases per million people in a year. Unusual joint diseases were much more likely. Bernstein ordered some specialized blood tests and an ultrasound of the wrist to see if there was fluid that could be tapped. If this was an infection, the bug could often be grown from these fluids. And she referred the patient to yet another doctor, Gavin McLeod, a specialist in infectious diseases.
McLeod saw the patient that weekend. He wasn’t certain that this was mycobacterium marinum, but it was a persuasive story. He stopped the prednisone and colchicine. These medications stop inflammation by slowing down the work of the white blood cells. And he put the woman on two antibiotics to fight M.M. Best to get started on the treatment for this infection even before the diagnosis was made.