Rare fungal infection blastomycosis is spreading beyond expected regions in the US: Study

A rare fungal infection believed to be present in the Midwest and Southeastern parts of the United States makes an appearance in an uncommon region, Vermont, new research from a recent study finds.

The illness, called blastomycosis, can resemble other respiratory infections and primarily lives in the environments that have moist soil and in decomposing matter like wood and leaves, according to the Center for Disease Control and Prevention.

Vermont's rate of blastomycosis trails Wisconsin, the state with the highest rate. With an average rate of 1.8 cases per 100,000 people every year, Vermont had higher rates of blastomycosis than all but one of the states, the study found. Wisconsin, the state with the highest rate of blastomycosis, has an average of 2.1 cases per 100,000 people.

Arkansas, Louisiana, Michigan, Minnesota, and Wisconsin are the only five states that have a public health surveillance for blastomycosis. The disease outside these states have not been researched in-depth yet.

USA TODAY spoke with Dr. Brian Borah, medical director for Vaccine-Preventable Diseases Surveillance at the Chicago Department of Public Health, who led the CDC study in Vermont. Borah, who previous was employed by the CDC as an Epidemic Intelligence Service Officer was stationed at the Vermont Department of Health to conduct research. In the study the doctors found that 114 of the patients diagnosed with blastomycosis during 2011–2020, 59% of them were male.

"We don't have a great explanation why it's possible that behavioral differences or occupational differences may account for some of that, that difference in epidemiology between the sexes, but our study was not able to answer that question of why but we did show that. That more men than women in Vermont's had blastomycosis during that time period," Borah said.

The study also highlights that of Vermont’s 14 counties, three of its north-central counties Lamoille, Orleans and Washington, had the highest number of blastomycosis reported. Borah said the reason for this is still under investigation.

"We don't yet know the answer to that question, we can look at other states that do have surveillance programs for blastomycosis. For instance, Wisconsin has a very robust program to look at this disease," Borah said. "They've also shown that there, that the counties that have the highest levels of disease are also in the northern part of the state. So it may have something to do with the climate, it may have something to do with proximity to certain waterways."

Based on the results of this study, the Vermont Department of Health is seeking to add blastomycosis to the list of reportable conditions in its Reportable and Communicable Diseases Rule to improve surveillance for this disease in Vermont, according to Dr. Natalie Kwit, State Public Health Veterinarian at Vermont Department of Health, and co-leader of the study.

CDC issues measles alert: Cases are up, urging health providers to watch for disease

Common symptoms of blastomycosis

The common symptoms of the rare fungal infection include:

• Fever

• Cough

• Shortness of breath

• Night sweats

• Muscle aches or joint pain

• Weight loss

• Chest, rib, or back pain

• Fatigue (extreme tiredness)

Borah explains that the skin lesion that are seen in patients that have blastomycosis cannot necessarily be compared to other diseases that have been seen in the past.

"[It] can be protruding lesions, and in some instances be quite big and ulcerating. Unlike something like M pox or chicken pox, where the lesions are fairly small and uniform and distributed throughout the body," Borah said.

Although the signs and symptoms seem easy to identify, doctors explain that the diagnosis may take awhile to take effect.

"Symptoms can take up to four months to appear, so you may not become sick until long after your exposure." said Dr. Suzanne Gibbons-Burgener, Public Health Veterinarian and Infectious Disease Epidemiologist at the Wisconsin Department of Health Services told USA TODAY "This is why it is important to go to a doctor if you experience symptoms of blastomycosis that do not get better on their own."

Gibbons-Burgener also adds that people with with weakened immune systems or underlying lung conditions are at a higher risk of developing severe illness from blastomycosis.

Often, many patients have been misdiagnosed with another illness because its symptoms are so similar to blastomycosis, Gibbons-Burgener says.

"Many people are first diagnosed with bacterial pneumonia instead of fungal pneumonia because the symptoms are similar," Gibbons-Burgener said. "Antibiotics used to treat bacterial pneumonia should not be used to treat blastomycosis."

Does blastomycosis have treatment options?

"There are diagnostic tests and anti-fungal treatments available for both humans and pets that are experiencing symptoms.," Gibbons-Burgener said.

Wisconsin cases of blastomycosis in dogs

In Feb. 2022, a veterinarian in St. Croix County, Wisconsin, told the Wisconsin Department of Agriculture Trade and Consumer Protection and the Wisconsin Department of Health Services that four dogs were diagnosed with blastomycosis. Three weeks later, two human cases were reported in the same area, according to a report from the CDC.

"About half of the people and dogs who are infected don’t have any symptoms," Gibbons-Burgener said. "Symptoms of blastomycosis are similar to other lung infections and can be mild or severe."

Blastomycosis is rare, but not a contagious disease

"The fungus is not spread from animal to person, person to animal, or person to person." Gibbons-Burgener said.

Blastomycoses has similar symptoms to pneumonia, involving the lungs and resporty system, but also has uncommon symptoms.

"Some of the other less common presentations include skin manifestations, so people can have skin lesions. More rarely, patients can have lesions within their bones. The infection can sometimes even involve the central nervous system or the brain," Borah said. "While this is a rare disease, and some people don't have any symptoms, it can still be a fatal disease. There are still people that die from this disease every year."

Can the climate affect the spread of the disease?

Gibbons-Burgener explains that the fungus grows and produces the infectious spores under specific conditions of humidity, temperature and nutrition. In Wisconsin, the fungus most commonly grows along waterways or in wooded areas where the rich and moist soil hasn't been moved for a long period of time.

"The risk of blastomycosis is thought to be higher in warmer months because fungal spores are more likely to form when the ground is not frozen," Gibbons-Burgener said. "Risk of exposure in Wisconsin is likely highest May through October."

According to Gibbons-Burgener, spores can survive in the soil for several weeks and are more likely to be present after being moistened from rain or falling river or flood waters. To reduce your risk of exposure, wearing respiratory protection and limiting activity while engaging in landscaping, hiking, camping or excavation that disrupt contaminated soil or decaying materials in advised.

What should the public know about blastomycosis?

"People and pets with healthy immune systems are unlikely to have a reoccurrence of blastomycosis after recovering from their first illness." Gibbons-Burgener said.

According to Gibbons-Burgener, 11% of patients who are diagnosed with moderate to severe blastomycosis die each year.

"This disease is probably more common in Vermont than was previously thought and perhaps in other states as well." Borah said. "I think it's important that clinicians be aware and to have this diagnosis in their list of possibilities when they're seeing patients."

This article originally appeared on USA TODAY: Rare fungal infection blastomycosis is spreading in US, study says