Morbidity vs. Mortality

Used to describe diseases or health conditions. Morbidity is the rate of people who have a condition. Mortality is the rate that the condition kills people.

Something with a high morbidity means it’s very prevalent through a population. Things like:

• Heart disease
• Diabetes
• Hypertension

Something with a high mortality is very fatal. Things like:

• Ebola
• Rabies
• HIV/AIDS
• Smallpox

Note that certain treatments and processes have brought down the morbidity of something, without affecting its mortality. Smallpox, for example, has been almost eradicated – its morbidity is low. But it’s still quite lethal if it were to reappear.

Other treatments bring down the mortality of a condition, while not affecting its morbidity. Type 2 Diabetes rates are higher than ever, but many treatments now exist to help us cope with the condition, thus lowering its mortality.

Other treatments affect both: various drugs to treat HIV/AIDS have made the disease survivable in the long-term, meaning its mortality has been lowered, and also have reduced the incidence of transmission and therefore its morbidity.

The base word – “morbid” – means:

Of, relating to, or characteristic of disease

I suppose this is what led to “morbid” also meaning something dark or gruesome.

Why I Looked It Up

I was reading a book on life expectancy. It went into details about disease rates and “morbidity” kept coming up. I always thought that was the same as “mortality,” so I looked it up. Turns out I was wrong.