The present invention includes a method for reducing viral, bacterial, protozoan, fungal and other parasitic contamination from a biological solution. Biological solutions include, but are not limited to, solutions comprising blood, a blood component, cell culture or a component of a cell culture. In accordance with the present invention, there is provided, a method of inactivating a pathogen in blood or blood product in a container, comprising contacting at least one of said blood, blood product and container with a composition of the present invention. In accordance with the present invention, there is provided, a medical device comprising at least a surface treated with an anti-pathogenic composition of the present invention or containing at least an anti-pathogenic composition of present invention. In accordance with the present invention, there is provided, an anti-pathogenic composition for use in disinfecting fluids and biological tissues and surfaces contaminated with fluids and/or biological tissues, which comprises an anti-pathogenic amount of at least one quaternary ammonium compound in association with an acceptable carrier. A preferred anti-pathogenic composition of the present invention further comprises a bisguanidine compound. In accordance with the present invention, there is provided a method for inhibiting in vitro or ex vivo infection or replication of human immunodeficiency virus in a biological fluid, comprising treating said biological fluid with an effective inhibiting amount of a bis-guanidine compound or a derivative thereof, and at least one quaternary ammonium compound in combination with a pharmaceutically carrier, such as DMSO.