A rule among public health workers in past years was to not let the sun set on an untreated case of syphilis.

About 20% of untreated cases of cutaneous anthrax will result in death.

Death occurs in between 10% and 30% of untreated cases.

Studies have shown that 77% of untreated cases result in mortality.

Severe cases, if untreated, can lead to arthritis, damage to the nervous system and heart disease.

Death occurs in 60 to 80 per cent of untreated cases, usually within a week of the first symptoms.

The mortality in untreated cases is about ninety percent.

Spontaneous remission with normal development has been observed in a few untreated cases.

In 1 out of 400 untreated cases Lemierre's syndrome occurs.

Some will spontaneously resolve, although untreated cases may result in death.