1 is any microbe capable of producing a disease. E.g. bacteria, spirochete, virus, fungi. Etc. 2 refers to the environment and objects on which an organism survives and multiplies. 3 is the path or way in which the organism leaves the reservoir. E.g. RS, GUT, GIT, skin and mm. 4 is the means by which the infectious agent passes through from the portal of exit of the reservoir to the susceptible host. This is the easiest link to break the chain of infection 5 is the venue where the organism gains entrance into the susceptible host. 6 the human body has many defenses against the entry and multiplication of organism.