The deadly disease was started in Europe. It them traveled to many other countries killing 1/3 of the Worlds population.
Black Death was caused by fleas biting rats, and once the fleas got the disease they would carry it onto people and bite them. Which was made into Black Death.
Most of the farmers were not able to go outside because they didn't want to take any chances of catching Black Death. Therefor, not only people would die from Black Death, they would also die from starvation.
Some of the symptoms of Black Death were; feeling nauseous, massive head aches, and throwing up constantly.
After scientists found a cure for Black Death, birth rates started to improve. Also the population increased 15% over the next year.