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Summer rains drive rare fungal disease in northern Minnesota

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Reported cases of a rare fungal infection are on the rise in northern Minnesota.

So far this year, more than 45 people 150 animals have been diagnosed with blastomycosis. By this time last year there were only 31 human cases and fewer than 100 animal infections.

The infections are caused by fungi living in the ground, said Malia Ireland, epidemiologist with the Minnesota Department of Health.

It’s common to breathe in the spores. Many people don’t get sick when they’re exposed. When they do, it’s sometimes serious. Roughly 10 percent of human cases are fatal.

This year’s 30 percent uptick in blastomycosis cases is largely due to a summer of heavy rains.

“This has been one of the wettest years on record,” Ireland said. “There has been a lot of flooding, which moved the soil around and exposed spores to the air.”

The fungus thrives in moist ground, especially in wooded land near rivers and lakes. Northern Minnesota is perfect habitat, and that’s where most of the cases were reported.

Most of the infected people interviewed by the Health Department said they had hobbies that brought them into regular contact with wet, wooded earth. Most of the animal cases were dogs.

“They dig with their noses right in the dirt,” Ireland said. “They’re smelling things all the time. It makes sense.”

Blastomycosis can be hard to diagnose. The most common symptoms are cough, fever and weight loss, “very non-specific symptoms,” Ireland said.

It’s commonly misdiagnosed as pneumonia. It’s only when antibiotics don’t work that doctors think to test for a fungal infection.