Naddition to replacing the president if necessary, it's the duty of the vice president to
a. serve as liaison to the judicial branch.
b. review laws before the president signs them.
c. serve as speaker of the house.
d. preside over the senate.

In addition to replacing the president if necessary, it's the duty of the vice president to "d. preside over the Senate", although this role is relatively insignificant now, as the Vice President is rarely there.

The constant presence of diseases or infectious agents within a given geographic area or population group. it may also refer to the usual prevalence of a given disease with such area or group. it includes holoendemic and hyperendemic diseases. a holoendemic disease is one for which a high prevalent level of infection begins early in life and affects most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than do children (malaria in many communities is a holoendemic disease). a hyperendemic disease is one that is constantly present at a high incidence and/or prevalence rate and affects all groups equally. so probably family history.