Because the HIV virus takes time to multiply and get established. Person might have been infected, but it not show up in tests for some time.
Italian was not the official language of the Roman Empire and therefore is not a legacy, so this would be the incorrect answer. During the Pax Romana, there were many key inventions such as the systems of roads, tunnels and bridges being created all over the empire. Aqueducts were one of the biggest inventions, with some of them still working today. The achievements made in law during that time are still used for Civil Law today.