Killing power of a disease is denoted by -

Ans. is 'c' i.e., Case fatality rate Case fatality rate (ratio)o CFR represents the killing power (severity) of a disease.CFR=Total no. of deaths due to a disease--------------------------------Total no. of cases of the same diseasex 100o CFR is typically used in acute infectious disease e.g. food poisoning, cholera, measles. Its usefulness in chronic disease is limited, because the period from onset to death is long and variableo CFR is closely related to virulence of agent.o Limitation of CFR is that time period is not specified.o The case fatality rate for the same disease may vary in different epidemics because of changes in host, agent and environment factorso Case fatality rate is the complement of survival rate.CFR = 1 - survival rateo CRF will be more if survival rate is less - more patients are dying due to disease (tCFR) or in other words less patients are surviving (>L survival rate).o Case fatality rate is a proportion (and not a rate or ratio).