Why was the black death so deadly and spread easily through population?

mount st. helens in washington erupts, causing a massive avalanche and killing 57 people on this day in 1980. ash from the volcanic eruption fell as far away as minnesota. seismic activity at mount st. helens, which is 96 miles south of seattle, began on march 16.

first it was savannah, then it was augusta, louisville, milledgeville, then atlanta.

i live in georgia.

-seth