1) During the course of disease in an infected host, when can a pathogen be transmitted? only during illness during the incubation period, illness, and convalescence only during illness and convalescence only during the incubation period and illness 2) The purpose of Koch's postulates is to show that... microorganisms can be isolated and grown in the lab. a specific microbe causes a specific disease. diseases caused by microorganisms can be transmitted between hosts. all microorganisms can cause disease..