Berton Roueche - The Medical Detectives Volume I

"I was gone a full week. But half of my mind never left Sioux Falls. Thyrotoxicosis is only rarely fatal, and there had been no deaths in York, but even so. . . I kept in touch with Dan by phone, and he was always reassuring. There were no ugly surprises. As soon as I got back home, I called Dan, and he and Jan and I sat down together in my office. They'd had a busy week. The case total was now twenty-three. Jan reported on the demographic data. The ages of the confirmed patients were much like those in the York outbreak, ranging from the pediatric to the geriatric. There seemed to be an equal number of men and women involved. I found that strange. Endocrine diseases tend to afflict women four times as often as men. We were definitely dealing with something unusual. As might be expected in an agricultural area like this, about half the patients were farm people. The geography was also interesting. There were still no cases in Sioux Falls, and Sioux Falls is the major trade and population center. The outbreak was confined between Valley Springs, on the west, and Worthington, Minnesota, on the east. The major case center seemed to be Luverne. About a third of the patients reported symptoms that included muscle aches and pains. That certainly sounded like a viral illness. Unlike a viral illness, however, there was no evidence of person-to-person transmission. There was no evidence of disease among people who worked together, or among friends who saw a lot of each other. The earliest onsets recorded by Dan and Jan were back in January. So this had been going on for quite a while. That was about where the investigation stood at the moment. Except that, because of the concentration of cases in and around Luverne, Dan and Jan had moved out of their rooms at the Sioux Falls Holiday Inn and were at rest in Luverne—at the Cozy Rest Motel."

The somewhat puzzling geographical picture of the outbreak drawn by Janet Farhie served as an accurate likeness through the last week of June and into the first week of July. Then it was abruptly blurred. On the afternoon of July 3, Dr. McMillin received a telephone call from a woman who identified herself as Rhonda Peskey. She and her husband and their young son lived in Sioux Falls. She had heard that there was an epidemic of thyroid disease going around, and she thought she and her family might have it. She hadn't seen a doctor. She had heard about the epidemic from her parents, who lived in Valley Springs. Dr. McMillin probably knew them. They were Larry and Margaret Long, and they owned the L&M Clover Farm Store there. But what she was really calling about was this: she was working as a waitress here in Sioux Falls, and she wanted to know if her illness was contagious. Should she quit her job, or what?

"I wasn't exactly alarmed," Dr. McMillin told me, with a shrug and a tight little smile. "But it was a disturbing piece of news. If the outbreak was spreading into Sioux Falls, we could be in for big trouble. Our investigation so far showed that in the area Jan had mapped the disease was occurring at a rate of at least one in every hundred persons. If it spread to Sioux Falls at that rate, we could be seeing patients in the thousands. So I had some serious questions for Mrs. Peskey. I asked if she and her family spent much time in Valley Springs. No—not really. Did they ever eat or drink the water there? Or stay overnight? Well, they never stayed overnight. They hardly ever ate anything there. Her parents had a little coffee shop attached to the main store, and she and her husband sometimes had a cup of coffee. She thought she knew most of the Valley Springs patients, but not as friends, and hardly ever saw them. She did sometimes bring some groceries home from the family store. I advised her to see her doctor—her and her husband and the little boy—and have the standard thyroid studies done, and to ask the doctor to report the results to me as soon as possible. I said I thought she could stay on her job. But I thought she should be very careful in handling food, and be careful about washing her hands. I hung up and did some thinking. The Longs, as far as I knew, were not among our Valley Springs cases. We knew there was little, if any, evidence of person-to-person transmission of this disease. Dan and Jan and I had talked that over and over. It was beginning to look less and less likely that we were dealing with an ordinary viral disease. Or any kind of viral disease. In that case, the possibility of some common source of infection was strongly indicated. There were several possible vectors. But the most likely—the most common—would be some food or drink that was shared by all."

"We're now well into July. We had made a point of keeping as quiet as possible about the outbreak. We didn't want a lot of community excitement until we knew a lot more than we did. That could only muddy the waters. But the news leaked out, as it always does, to the media. And nothing much happened. It was only a one-day story. We had been in touch with the Minnesota Health Department all along, of course, but now all hands decided it was time to meet. We set up a conference for July 8 in Worthington, which is between here and Minneapolis. Hedberg and Osterholm were there, along with various other health workers in the community. Hedberg presided. We brought each other up to date. We heard reports that a lot of the patients were worried that the water supply might somehow be to blame. Or insecticides. There was even a group that thought the trouble might have been brought on by some recent tornadoes. We discussed the question of genetic susceptibility. As it turned out, many people in the outbreak area had evidence of thyroid hormone in their blood but were not clinically ill. Even fairly high levels of hormone can be tolerated by some young people and adults in good health. We decided to send a letter to physicians in a wide area of the two states soliciting information about cases of painless hyperthyroidism. The South Dakota letter went out over the signatures of Kenneth A. Senger, director of the Division of Public Health, and myself. The results, I might as well say now, were positive in a negative sense. The response left the geography of the outbreak much as it had been earlier defined. The number of cases rose from week to week, but there were none really outside the area.

"I received a phone call from Rhonda Peskey's doctor. He had confirmed that she and her son were both thyrotoxic. I decided it was time to treat myself to a little shoe-leather epidemiology. The next morning, I drove over to Valley Springs. The Clover Farm store wasn't hard to find. It's practically the only store in town. With Sioux Falls only ten miles away, a convenience store is about all a little place like Valley Springs can support. I went in and introduced myself to Larry Long. We had a cup of coffee together and talked about where he bought his stock. We talked about bread and eggs and meat and milk and soft drinks and staples. Practically everything came from distributors in Sioux Falls or one of several other Large distributors in the region. There was nothing surprising in that. And, of course, the same distributors supplied the various stores in Sioux Falls. Practically all the Clover Farm meats came from Sioux Falls. Some came from a plant in Luverne. That was a special kind of beef that Larry Long ground himself, for customers who liked their hamburger lean. He called it his lean cuisine. It was extra lean, almost no fat at all. We talked for about an hour, and Margaret Long joined us for another cup of coffee. We talked about the outbreak. Some of their customers were sick. Some weren't. They themselves were well. I drove back to Sioux Falls, thinking about what I had learned. There was only one thing that stood out. That was that extra-lean hamburger. Was that a clue? But how? When I got back to my office, I found a message from Dan. The number of confirmed cases was climbing. There were more than fifty now in Luverne alone.