Fungal infections are difficult to diagnose. The most common filamentous fungal infection, aspergillosis, carries with it a high mortality. Culture of the organism is difficult and obtaining samples, e.g., through a lung biopsy, sometimes causes morbidity. Biomarkers that indicate ‘early’ infection in it development are sought after. One such biomarker is detection of galactomannan (GM), a polysaccharide that is attached to hyphal cell walls and secreted during growth of the organism. Galactomannan is excreted in urine. Disclosed herein is a lateral flow assay comprising monoclonal antibodies that recognize specific residues of Aspergillus fumigatus for detecting GM in urine samples to provide a point-of-care detection device to allow for frequent screening and early diagnosis in patients at high risk for infection.