It all started in 1998 when she moved to Mexico, she told Bonlie. She had a few days of diarrhea and hasn’t felt the same since. Within weeks, she developed a sensitivity to corn. Every time she ate it, she felt really bad. Then it was gluten. Then dairy products. Then the fats. Spicy foods were out of the question. After being diagnosed with IBS, she tried a diet low in certain types of gas-triggering carbohydrates that many people with IBS find helpful. And initially, that helped. But at this point, she was way beyond that. She couldn’t eat most fruits and many vegetables. Most of the time all she could handle was the few grains that didn’t contain gluten, baked chicken or fish and carrots.
She often felt better after taking antibiotics, which made her think that whatever she had was contagious. But she also knew that IBS gets better after antibiotics – for a while. She had been tested for every infection her various doctors could think of. She once had a parasite – she worked in public health and traveled extensively in areas where parasites were common – and she was treated for it, with a temporary improvement in her symptoms. She took a few courses of antibiotics for small intestinal bacterial overgrowth (SIBO), a disorder believed to cause gastrointestinal distress in some patients diagnosed with IBS. Patients with SIBO have more bacteria than normal in the upper parts of the gastrointestinal tract. Like IBS, it is a chronic disorder and only temporarily improves with antibiotics. Beyond that, the tests hadn’t been revealing.
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After hearing her story, Bonlie wasn’t sure if the woman had an infection or if it was all due to her irritable bowel. But since her symptoms were so prominent and her diet so limited, he decided to test her for diseases that, in his experience, other doctors often overlooked. He suspected she might have Lyme disease. It wasn’t something she would have learned in Mexico; infection with Borrelia burgdorferi – the bacteria that causes Lyme disease – is quite rare in Central America. But she certainly could have had it in Maryland. And many of his other patients had them. He also looked for other infections that were often overlooked – ehrlichia, Bartonella, tularemia, Epstein-Barr. He gave her some supplements that he thought might be helpful.
Two weeks later, she returned to Bonlie’s office to get her blood test results. Tests of her immune system indicated that she had been infected with an insect called Brucella. It is a bacterium that mainly infects cows, sheep, goats and pigs and is usually transmitted to humans through the milk or meat of an infected animal. It’s rare in the United States. Here, most milk is pasteurized and most farm animals are vaccinated against Brucella. But worldwide, it is the most common disease that humans contract from animals. Given her travel history, Bonlie acknowledged that this may not have been such a surprising result. And brucellosis has chronic forms that can drag on for years. There was, however, a strange aspect to the result. In immune system tests, it is possible to distinguish between a new infection – which shows up as positive IgM, the rapid-response antibody – and older infections, which show up after a few weeks as positive IgG . She should have IgG – but she didn’t. She only had IgM.
What did that mean? How to interpret this positive test for a recent Brucella infection, in a patient who drank no dairy, ate little meat, had not left the country for several years and had these symptoms for decades? Bonlie sent the sample back to the lab to measure the number of antibodies present. When the level came back very high, Bonlie was convinced. He recommended that she take two antibiotics – doxycycline and rifampin – for a total of six weeks to treat the infection.