How fire ant bites led to discovery, treatment of rare disease for Texas woman

Jill Zinsmeyer came to Austin for love, but Austin didn't love her. Living in Napa Valley, Calif., before the move, Zinsmeyer hadn't come into contact with such things as fire ants and the small biting insects known as no-see-ums.

She camped as a kid and had her share of mosquito bites, but that was nothing like what Austin was about to deliver.

The former emergency room nurse was bitten by no-see-ums when she was visiting Austin around 2013. Her body "swelled up like crazy," she said. Within five minutes, her blood pressure had dropped and she had lost consciousness, but then she came around.

The next time she had such a strong reaction was in 2017, and by then she lived here, in the Lakeway area. She and her husband, Kurt, had a new puppy that got into a fire ant pile. When she scooped up the puppy, four fire ants bit her.

"Had my husband not been there, I would not be here today," she said.

Within minutes, she was crawling to her bed. She lost consciousness and woke up in the emergency room.

"It was kind of a long road," she said. "With every subsequent bite, my symptoms would get worse."

This wasn't just an allergic reaction. Zinsmeyer would be diagnosed with the rare indolent systemic mastocytosis, an overreaction of the mast cells, a type of immune system cell. This disease occurs in about 1 in 10,000 people.

"This is a disease that is often missed," said Dr. Prithviraj Bose, a hematologist at the MD Anderson Cancer Center in Houston. "It can take years to get diagnosed."

Unless a provider is thinking about this disease, Bose said, "it might be hard to put the dots together."

Learn more: A $5 million gift from Firefly Fund launches rare disease center at Dell Medical School

A blood test measured the amount of tryptase in Zinsmeyer's blood. Tryptase is an enzyme found in the mast cells and is high after an allergic reaction. It had been a few weeks since the fire ant bites, but her tryptase level was still high.

She looked up "high tryptase level" on Google and found that it typically suggests mastocytosis. "It only came back with one answer, she said. On the computer, she saw a list of symptoms of "all the peculiar things that would happen to me," she said. That included blotchiness when she went from hot to cold, allergic reactions and sensitivity to smells.

A new doctor would later do a bone marrow biopsy, which confirmed the diagnosis and found the genetic mutation.

At the time, the only solution was injections every two weeks. Those shots were painful and didn't provide a change in her symptoms, she said. After six months, she quit getting them.

Zinsmeyer felt like "a hot potato," she said. She went from allergist to allergist, hematologist to hematologist. She finally ended up with Bose, who was working on a clinical trial of a new medication for systemic mastocytosis.

Systemic mastocytosis is similar to cancer in that it is a buildup of abnormal cells — in this case mast cells, Bose explained.

"They just get out of control and multiply," he said.

People with systemic mastocytosis can have a variety of symptoms. As with Zinsmeyer, it can mimic an allergic reaction with tongue swelling, hives and shortness of breath. It also can cause problems in the muscles and bones as well as intestinal distress.

Bose was testing the medication avapritinib, which was approved by the Food and Drug Administration for advanced systemic mastocytosis in 2021 and for the indolent form in 2023. The medication is a once-daily, 25-milligram pill.

Zinsmeyer began participating in the third stage of this clinical trial at the end of 2021. Initially she was on the placebo, but she began to get the actual medication six months into her participation.

Now with the medication, her symptoms are decreasing and she is progressively getting better.

Her fatigue has eased. She is less likely to get a blotchy rash when she moves from hot to cold temperatures. She can better tolerate the heat of summer. She hasn't had to use her EpiPen in a while, but she always carries it with her. She is very aware of her surroundings and won't step off the pavement.

"She's got a lot more energy," Kurt Zinsmeyer said. "She's not quite so lethargic. She had been pretty much housebound, and that is not the case anymore."

In fact, she is heading to Grenada to take a sailing class.

"I'm so much better," she said.

This article originally appeared on Austin American-Statesman: Fire ant bites almost kill Texas woman; medication helps with disease