The fungi that causes serious lung infections is now present across the United States

Doctors should be on the lookout for the organisms, researchers say

Three types of fungi that cause serious lung infections that were once thought to be limited to certain areas of the United States are now widespread.

In 1955, Histoplasma fungi grew primarily in the Midwest and parts of the East and South, and that’s where most Histoplasmosis infections occurred. But Medicare records from 2007 to 2016 show that 47 states and Washington, DC, had histoplasmosis cases above a certain threshold, researchers report Nov. 11 in Clinical Infectious Diseases.

These fungi are now “much more common than we think they are,” says Andrej Spec, an infectious disease physician and mycologist at Washington University School of Medicine in St. Louis.

Doctors using maps from the 1950s and 1960s may fail to diagnose infections in patients living outside the historical boundaries of the fungus. Such missed or delayed diagnoses can have fatal consequences.

Spec and colleagues drew updated maps of Histoplasma cases and two other fungi whose range has expanded, possibly due to climate change.

Cases of coccidioidomycosis, caused by Coccidioides fungi, have spread from their roots in 1955 in the Southwest to 35 states, according to Medicare records. Coccidia include fungi that cause valley fever (SN: 11/29/21). The fires have been linked to an increase in valley fever cases in recent years (SN: 4/13/21).

Like Histoplasma, Blastomyces was found mostly in the Midwest and East in 1955. But from 2007 to 2016, 40 states reported cases of blastomycosis above a certain threshold, the researchers found.

When diagnosing infections, doctors are taught to look for horses, not zebras, which means tests usually focus on common infectious organisms, not rare ones, Spec says. “We’ve talked about these [fungi] as zebras… but they’re not zebras. It’s the Clydesdales. Clydesdales aren’t the most common horse you’ll see, but they’re still horses.”



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