Abstract: A reagent for microscopy-based detection of pathogens, especially spirochetes, from body fluids characterized by that containing the following ingredients: tetracain (125-200 mg/l), mannit (1500-2000 mg/l), EGTA (etilene bis[oxyetiline-nitrilo]-tetraacetate), 0.76-0.114 mg/l magnesium-chloride (preferably in amount of 0.10 mg/l), caffeine-sodium-benzoate (2000-4000 mg/l), glucose (1800-2200 mg/l), glycerol (75-105 mg/l), optimally tri-sodium-citrate (preferable in an amount of 10000 mg/l), Hoechst 33342 dye (1.11 mg/l), if required 20 to 40 ml of distilled water and RPMI 1640 culture media to make 100 ml. Also, a method for detecting pathogens.