One indicator of human development is the number of people who die from preventable diseases and epidemics.
For example, the plague, as “Black Death” one of the horrors of the Middle Ages, is extinct in Europe, but still occasionally occurs worldwide – in “underdeveloped” regions, of course. Insufficient hygienic conditions are the first prerequisite for the occurrence and spread of this disease. After all, at least there are effective drugs to treat it.
Smallpox was a very dangerous disease. This epidemic also claimed millions of lives, especially in areas where there was no immunity in the population. The American Indians are to be mentioned here, who were particularly numerous victims of smallpox.