The number of new and old cases of a disease in a population during a specified time, regardless of when it first appeared. This measure indicates the seriousness of the disease and is referred to as the

Prevalence rate

Explanation:

In epidemiology, the seriousness of a disease can be measured by the prevalence rate.

Prevalence rate refers to the number of new and old cases of disease in a population during a specified time regardless of when it first appeared.

It should not be confused by incidence rate. Incidence rate refers to the frequency of the number of new cases of a disease in a population at a specified time.

Prevalence rate shows or indicates how widespread the disease is whereas incidence will tell about the risk of contracting the disease.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.