Epidemic means very prevalent in a specific area: “The doctors were afraid of an epidemic of flu in the schools during the winter.”
Pandemic, on the other hand, means that which occurs over a wide geographical, or international, area and effects large numbers of individuals: “The outbreak of dengue appeared to be pandemic and the medical profession worked hard to contain it.”
The pandemic enthusiasm for soccer spread like an epidemic among the fans; especially, those for whom soccer is endemic to their culture.