What metric is used to measure the severity of a disease related to the degree of pathogenicity of the organism?

The case fatality rate is the correct metric to measure the severity of a disease as it reflects the proportion of individuals diagnosed with a particular condition who ultimately die from that condition within a specified time frame. This rate is highly relevant in understanding the degree of pathogenicity of the organism causing the disease.

By focusing on the proportion of deaths among those with the disease, the case fatality rate provides insight into how lethal a disease is, which allows for a clearer understanding of its severity. A high case fatality rate indicates a highly pathogenic organism, whereas a lower rate might suggest less severe outcomes for those infected.

Other metrics, while useful in different contexts, do not directly measure disease severity in the same way. The proportionate mortality rate focuses on the proportion of total deaths attributed to a specific cause but does not gauge the impact or severity of the disease among those diagnosed. The cause-specific mortality rate deals with deaths due to specific diseases but does not account for those affected who survive. The crude death rate reflects total deaths in a population without distinguishing the causes or related severity of diseases. Therefore, the case fatality rate stands out as the most relevant metric for assessing how deadly a disease is among those infected.