Emergomycosis

Cause

Emergomycosis is caused by the Emergomyces species, a dimorphic fungus previously classified under the genus Emmonsia. Following a revised taxonomy in 2017 based on DNA sequence analyses, five Emmonsia-like fungi were placed under the separate genus Emergomyces: Emergomyces pasteurianus, Emergomyces africanus, Emergomyces canadensis, Emergomyces orientalis, and Emergomyces europaeus. Emergomyces africanus accounts for over two-thirds of documented human cases. Cases in Europe are much rarer and are usually due to E. pasteurianus. The fungus lives in soil as a harmless mold and is transmitted by inhaling its spores. Inside the body, it converts to yeast-like cells that invade beyond the lungs. In people with HIV, emergomycosis has been associated with immune reconstitution inflammatory syndrome following initiation of antiretroviral treatment. The fungus transforms into yeast only after reaching the deep portions of the lungs, and it tends to spread hematogenously or through lymphatics to other organs, causing life-threatening infections such as endocarditis. Risk factors include HIV, organ transplant, and steroid use, especially in HIV-positive individuals with CD4+ T-cell counts below 100 cells/mm³.