According to Koch's postulates, in order to prove that any given infectious agent causes a certain disease, a scientist must satisfy all of the following requirements EXCEPT:
A. the pathogen must be cultured and isolated from every case of the disease
B. the disease is caused by the triangle of infection, host, environment and the pathogen
C. the same pathogen must be re-isolated in the diseased host
D. the cultured pathogen must cause the disease when inoculated into a healthy host
E. the pathogen must be present in every case of the disease
Ans: B. the disease is caused by the triangle of infection, host, environment and the pathogen
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