Dimorphic fungal diseases are defined as infections caused by fungi that exist in two forms: as yeast in warmer temperatures (such as in the human body) and as mold forms in cooler temperatures (such as in laboratory cultures). These infections can have a regional distribution and thus they are often referred to as endemic mycoses. Importantly, the at risk regions of these pathogens is growing, likely related to changes in climate. Common examples include histoplasmosis, coccidiomycosis, and blastomycosis, which can present in pulmonary, cutaneous, or disseminated forms. These pathogens are typically inhaled in their mold state in nature. For immunocompetent individuals these infections can be asymptomatic or self-resolving. Rarely, they cause severe disease in otherwise healthy people. In immunocompromised patients, they can cause significant illness including dissemination from lungs to the central nervous system.
What are dimorphic fungi?
Dimorphic fungi are defined as infections caused by fungi that exist in two forms: as yeast in warmer temperatures (such as in the human body) and as mold forms in cooler temperatures (such as in laboratory cultures). They are often associated with specific geographic regions and can exhibit different growth forms depending on environmental conditions.
Who gets dimorphic fungal diseases?
Anyone exposed to environments where these pathogens exist are at risk for infection. Individuals with intact immune systems can have severe presentations but often have asymptomatic or self-limiting illness. Immunocompromised patients are at risk for more severe and persistent forms of these infections.
What causes dimorphic fungi infections?
Humans typically acquire these infections by inhaling the mold form’s spores from the environment.
How are dimorphic fungal diseases diagnosed?
Specimens for testing can be collected from lung, blood, bone marrow, urine, or other organ tissues. The specimens are examined microscopically, cultured or tested by PCR for antigen or by antibody assays specific to a given fungal organism.
What is the treatment for dimorphic fungi diseases?
Dimorphic fungal diseases are typically susceptible to voriconazole, posaconazole, and amphotericin B formulations. Fluconazole and echinocandins are relatively inactive.