An uptick in reported cases of a fungal infection has prompted the Minnesota Department of Health to issue an advisory to health providers across the state.

Blastomycosis, caused by inhaling spores from infected soil, is an uncommon ailment even in an active year. But Dr. Malia Ireland, the Minnesota Department of Health epidemiologist who sent out the advisory Thursday, Sept. 5, said she has had 43 cases reported so far this year, compared with 31 at the same time last year. Among animals — mostly dogs — the number of cases is up 35%.

The disease can be serious and even fatal, Ireland said — 10% of people diagnosed with blatomycosis in Minnesota die from it. On the other hand, it’s estimated that about half the people who have the spores never even get sick.

The infection has an incubation period of 45 days, Ireland said, and since people are most likely to be around the soil during the summer, the number of cases tends to rise in September. In the U.S., it might be most common in Wisconsin, with the highest rate in northern counties, according to the U.S. Centers for Disease Control and Prevention.

Likewise, in Minnesota it’s most common in the north, Ireland said.

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"The blasto like moist oils with decomposing organic materials — so heavily forested areas," she said. "You have a tendency to have more blasto versus an area that’s a little bit more dry and arid, kind of like southwestern Minnesota."

In fact, St. Louis County was found to be where exposure to the fungus occurred in far more cases over the past 20 years than any other Minnesota county, according to health department data. In 1999, 18 people in Mountain Iron were diagnosed with blastomycosis — the largest outbreak ever recorded, according to the state epidemiologist at that time.

But Ireland sent her advisory statewide in part because so many Minnesotans spend part of their summers in northern Minnesota, she said.

Even in the northern part of the state, though, blastomycosis is not the first diagnosis that occurs to physicians, local infectious disease doctors said. That’s because it looks like diseases that are much more common.

Dr. Amanda Noska, an infectious disease specialist at Essentia Health, said that in its most common form, blastomycosis produces fevers and coughs, chest pain, breathing difficulties, sweating and loss of appetite.

It looks like pneumonia. In fact, it is a form of pneumonia, said Dr. Harmony Tyner of St. Luke’s Infectious Disease Associates — "pneumonia" simply meaning lung infection. It’s not caused by bacteria, so antibiotics don’t work. But the patient may run through several courses of antibiotics before medical professionals start to think it’s something else, Tyner said. Even then, they’re probably not thinking blastomycosis.

"By that time, people are often pretty frightened, and they’re usually thinking about cancer or something else," Tyner said.

In fact, blastomycosis often is discovered when a biopsy of a spot in a patient’s lung is sent to a cancer pathologist who finds the fungus instead of cancer, she said.

Less frequently, blastomycosis can show up as skin lesions. But even then, Tyner said, the patient often will be treated for warts — with no results — before anyone suspects blastomycosis.

Both Tyner and Noska said they’ve seen blastomycosis cases this year.

Once the disease is diagnosed, antifungal treatments are available, the doctors said. In severe cases, the patient may have to be treated through an IV in the hospital. In many cases, the patient can take a pill, although they’ll have to keep doing so for six to 12 months. An oddity with the medicine, Noska said, is that patients are told to take it with orange juice or cola. "The reason is they’re acidic, so it helps them to be metabolized and to get proper bloodstream concentration."

But the earlier it’s treated, the better the results, Ireland said. That’s why she wants to call attention to it.

"Every year there are cases that take a long time to get diagnosed," she said. "And so because this disease seems to be happening more this year, we wanted providers to really be aware of that and to be thinking about it so they can test patients earlier."