Viral Epidemiology Study the distribution of determinants of disease in human populations Endemic (infections present at fairly low but constant level) Epidemic(infections occur greater than usually found in the population) e Pandemic(infections are spread worldwide)Viral Epidemiology z Study the distribution istribution of determinants rminants of disease in human populations z Endemic (infections present at fairly low but constant level) z Epidemic (infections occur greater than usually found in the population) z Pandemic (infections are spread worldwide)