Methods are also provided for isolating and using a whole-saliva leech extract in the treatment of a bacterial skin infection. The methods can include feeding a phagostimulatory agent to a leech; inducing a regurgitation in the leech, the inducing including placing the leech in an environment having a temperature of less than about 0° C.; and, collecting an unrefined, whole saliva in the regurgitation of the cooled leech. The methods can include revitalizing the leech by warming it at a temperature ranging from about 5° C. to about 40° C. Stable, lyophilized, whole-saliva extracts of a leech are also provided, the extract having a stable activity when stored for use at a temperature below about −20° C., the extract maintaining at least 70% of the activity for at least 6 months. The extracts can be used to treat solid tumors, treat liquid tumors, treat diabetes, treat a viral disease, treat a parasitic disease, treat an antibacterial disease, or serve as an anti-oxidant.