Final answer:
The outbreak of infectious diseases in the Roman Empire was catalyzed by urbanization, trade routes, and overcrowding.
Step-by-step explanation:
The outbreak of infectious diseases during the Roman Empire can be attributed to various factors such as urbanization, trade routes, and overcrowding. The movement of people and goods in a densely populated empire facilitated the spread of pathogens, leading to pandemics like the Antonine and Justinian plagues. Poor sanitation and hygiene practices also contributed to the prevalence of diseases in urban environments.