Enhanced Detection of Coccidioides spp. Fungi from Environmental Samples Using Droplet Digital PCR

Area of Science:

• Environmental microbiology
• Mycology
• Infectious disease epidemiology

Background:

• Coccidioidomycosis, or Valley fever, is a reemerging fungal disease prevalent in arid regions.
• Environmental detection of Coccidioides spp. is hindered by challenges like spatial variability and low DNA levels.
• Standardized methods for environmental fungal detection are lacking.

Purpose of the Study:

• To evaluate droplet digital PCR (ddPCR) for detecting Coccidioides spp. DNA in environmental samples.
• To compare the sensitivity of ddPCR against nested PCR for fungal DNA detection.
• To assess the feasibility of environmental surveillance in understudied regions like Baja California, Mexico.

Main Methods:

• Collected 74 soil samples from rodent burrows across 5 locations in Baja California.
• Utilized ddPCR and nested PCR techniques targeting the internal transcribed spacer 1 region.
• Compared the performance of both PCR methods for Coccidioides spp. detection.

Main Results:

• ddPCR successfully detected Coccidioides spp. DNA at all 5 sampling sites.
• Nested PCR only detected Coccidioides spp. DNA at 1 out of the 5 sites.
• ddPCR showed significantly higher sensitivity compared to nested PCR in this study.

Conclusions:

• ddPCR shows promise as a sensitive tool for environmental detection of Coccidioides spp.
• This method could facilitate the identification of environmental hotspots for Coccidioidomycosis.
• Enhanced environmental surveillance using ddPCR may support public health interventions to mitigate infection risk.