Virulence of a disease is indicated by

CASE FATALITY RATIO Case fatality rate represents the killing power of a disease. It is simply the ratio of deaths to cases. The time interval is not specified. Case fatality rate is typically used in acute Infectious diseases (e.g., food poisoning, cholera, measles). Its usefulness for chronic diseases is limited, because the period from onset to death is long and variable. The case fatality rate for the same disease may vary in different epidemics because of changes in the agent, host and environmental factors. Case fatality is closely related to virulence. Ref: Park 25th edition Pgno : 66