english: This is due to dermatophyte Trichophyton rubrum and Trichophyton mentagrophytes (they affect nails in 90% of cases), mold fungi (Aspergillus niger and Candida).
non_english: Iki amarga dermatophyte Trichophyton rubrum lan Trichophyton mentagrophytes (padha nyebabake kuku ing 90% kasus), fungi jamur (Aspergillus niger and Candida).