Differentiate the terms in each of the following pairs:
a. etiology and pathogenesis
b. infection and disease
c. communicable disease and noncommunicable disease
For which of the following reasons are most animal poxviruses unable to infect humans?
a. Affected animals are not in frequent contact with humans.
b. The human immune system makes it impossible for the foreign viral particles to
reproduce effectively.
c. Attachment to human cells is unlikely.
d. Human cells lack the necessary enzymes for infection.