Chaetomiaceae Fungi, Novel Pathogens of Equine Neurotropic Phaeohyphomycosis.

This study documents the first cases of a rare fungal infection caused by the Chaetomiaceae family in horses. The researchers evaluated seven reported cases and used molecular diagnostic techniques to identify the pathogens.

Objective of the Study

• The primary objective of this research was to study equine mycotic (fungal) encephalitis, a brain inflammation caused by a fungal infection.
• The researchers focused on characterizing key histopathologic features of this disease and identifying the causative organisms.
• The study is significant given the emergence of novel pathogens by previously unrecognized fungi, particularly from the Chaetomiaceae family.

Methodology and Findings

• The researchers evaluate seven reported cases of equine hyphal mycotic encephalitis by using histopathology, the study of changes in tissues caused by disease.
• They extracted DNA from affected brain tissues and performed a panfungal PCR to target the ribosomal RNA large subunit coding region and the noncoding internal transcribed spacer-2 region. This allowed them to identify and classify the causative fungi by comparing the obtained genetic sequences with published fungal genomes.
• The affected animals ranged from 8 to 22 years old and showed symptoms of neurological disorders. Their brain tissue exhibited signs of inflammation, necrosis, vasculitis, and fungal hyphae.
• The study identified four DNA sequences that showed more than 98% homology (biological similarity) with species in the Chaetomiaceae family. This included Acrophialophora fusispora, Acrophialophora levis, and Chaetomium strumarium.

Significance of the Findings

• This research contributes crucial knowledge on equine neurotropic phaeohyphomycosis. It’s the first report documenting that Chaetomiaceae fungi, specifically Acrophialophora fusispora, Acrophialophora levis, and Chaetomium strumarium, can cause these types of infections in horses.
• Previously, infections involving Chaetomiaceae fungi were documented in humans only. The finding aids in understanding the diversity and pathogenic potential of dematiaceous fungi under the Ascomycota phylum.
• These results also provide a foundation for future studies dealing with various emerging fungal pathogens, their epidemiology, and their potential impact on animal health.