Isolated nucleic acids, kits and methods are disclosed for detecting, quantifying and/or identifying a fungal species in a sample or for diagnosing jejunal hemorrhage syndrome in a subject. The methods generally include amplifying a fungal nucleic acid sequence present in the sample using a primer selected from the group consisting of: SEQ. ID NO 5, SEQ. ID NO 6, SEQ. ID NO 7, SEQ. ID NO 8, SEQ. ID NO 9, SEQ. ID NO 10, SEQ. ID NO 11, SEQ. ID NO 12, SEQ. ID NO 13, SEQ. ID NO 14 or SEQ. ID NO 16; and observing or measuring the amplified nucleic acid sequence. The fungal species can thereby be detected, quantified, and/or identified. Fungal contamination also can be detected or measured in a biological or feed or food sample.