• Posted April 3, 2023

Wisconsin Fungal Infection Sickened 4 People, 5 Dogs

The first season of "The Last of Us" may be over, but many folks have been left with an abiding fear of fungal infections.

Some of that fear might be well-founded in real life: A cluster of the fungal infection blastomycosis was found in dogs and humans in Wisconsin in 2022, which led to serious health consequences, U.S. health officials report.

Blastomycosis is caused by a fungus called Blastomyces, which lives in moist soil and decomposing wood and leaves.

Most people who breathe in the spores don't get sick, but some who do develop symptoms like fever and cough, and the infection can sometimes become serious, even fatal, if it is not treated, according to the U.S. Centers for Disease Control and Prevention. In the Wisconsin outbreak, two people were hospitalized and one died.

"Four people and five dogs living in the neighborhood were diagnosed with blastomycosis; two of the people were hospitalized and one died," said lead researcher Hannah Segaloff, a CDC career epidemiology field officer with the Bureau of Communicable Diseases in the Wisconsin Department of Health Services.

Fortunately, these infections are rare, she said, "but how uncommon it is varies widely by geographic location in the United States." The fungus mainly lives in the Midwestern, South Central and Southeastern U.S. states, particularly in areas surrounding the Ohio and Mississippi River valleys, the Great Lakes and the St. Lawrence River.

"Wisconsin likely has the highest incidence of Blastomyces infection in the country, with an estimated annual statewide incidence of more than 2 cases per 100,000 residents," Segaloff said. "Some high-incidence counties in Wisconsin report 20 to 40 cases per 100,000 population."

Investigation into this cluster, including health alerts to local doctors, veterinarians and residents alike, led to more information about blastomycosis and its symptoms being available to the community, Segaloff said.

About half of people infected with Blastomyces will develop symptoms, according to the CDC. Symptoms can include:

• Fever
• Cough
• Night sweats
• Muscle aches or joint pain
• Weight loss
• Chest pain
• Fatigue

Symptoms usually appear between three weeks and three months after breathing in the spores.

"Blastomycosis is treated with antifungal medications in people and in dogs," Segaloff said. "Depending on the severity of the infection, treatment last for six months to one year."

In some people, particularly those with weakened immune systems, blastomycosis can spread from the lungs to other parts of the body, such as the skin, bones, joints and the central nervous system, the CDC noted.

"Clinicians and veterinarians should consider blastomycosis among patients who have compatible symptoms and live in or have traveled to areas where the Blastomyces fungus is endemic," Segaloff said. "This is particularly important among patients with respiratory symptoms that resist treatment with antibiotics. Early recognition and treatment with appropriate antifungal medications help prevent severe blastomycosis."

Infectious disease expert Dr. Marc Siegel, a clinical professor of medicine at NYU Langone Medical Center in New York City, noted that blastomycosis is not contagious.

Blastomycosis not preventable, and it may not be possible to completely avoid being exposed to the fungus in areas where it is common.

"Immunocompromised people have a poor prognosis, but overall prognosis is good and is 80% to 95% percent successful, but early identification and treatment is key," Siegel said. The most commonly recommended antifungal drug is itraconazole for mild to moderate blastomycosis. Amphotericin B is usually recommended for severe blastomycosis in the lungs or infections that have spread to other parts of the body, according to the CDC.

The report on the infections was published March 31 in the CDC's Morbidity and Mortality Weekly Report.

Blastomyces isn't the only emerging fungus threat in the United States.

Candida auris has surged across the nation since the first case occurred in 2013, CDC researchers reported last month in the Annals of Internal Medicine.

The yeast easily spreads through touch, and can remain viable on surfaces for months, said lead researcher Dr. Meghan Lyman, a medical officer in the CDC's Mycotic Diseases Branch.

While it's innocuous to healthy people, C. auris can cause severe and life-threatening infections in people whose immune systems have been compromised by other illnesses.

The percentage of dangerous infections caused by C. auris has increased every year in the United States, from a 44% increase in 2019 to a 95% increase in 2021, the study found.

More information

The U.S. Centers for Disease Control and Prevention has more on blastomycosis.

SOURCES: Hannah Segaloff, PhD, U.S. Centers for Disease Control and Prevention; Marc Siegel, MD, clinical professor, medicine, NYU Langone Medical Center, New York City; Morbidity and Mortality Weekly Report, March 31, 2023