The phrase "major epidemics" refers to the widespread outbreak of illnesses that affect a large number of people within a specific region or population. Full definition
One of the first major epidemics of the disease in the U.S., it devastated America's early capital. (scientificamerican.com)
As a result C. difficile bacteria are now widespread in many hospitals and they are capable of causing major epidemics that are becoming increasingly frequent and severe. (sangerinstitute.blog)
Panama was one of the first countries to experience major epidemics. (apsnet.org)