#1 In the civilized world, as everywhere else, the primary route of infection is contact or close proximity to infected people, or contact with insects that carry disease. You do not have to be anywhere near a hospital to get an infectious disease.
#2 While the behavior of addicts might cause them to forego basic hygiene measures, drugs do not cause infectious disease. In addition, most infectious diseases are not STDs.
For your reading pleasure, you can look up the CDC’s weekly compendium of infectious disease deaths.
Morbidity and Mortality Weekly Report (MMWR) at https://www.cdc.gov/mmwr/index.html.
https://wonder.cdc.gov/nndss/static/2018/23/2018-23-table1.html
That’s OK, the CDC gets much of its data from my database.
Infectious disease ranges from common cold and flu to life threatening. Of course a few do die from cold and flu. Amazingling most of the ones who die from these, acquire it in healthcare facilities. That is because it is the weak who are already in a healthcare facility who are most vulnerable. And infectious disease is far more common in healthcare facilities than most anywhere else.
As for lifestyle and infectious disease, bad lifestyle leads to STDs... But it also leads to a lot of other infectious diseases besides STDs.
Yes, the rest of us do get infectious disease. The entire population can be separated into 3 or 4 categories. First, there is a bump in cost for infant and maternity costs. The single biggest cost factor in this is moms with bad lifestyles.
Then there are children 1-18. The average cost per child is extremely small, almost insignificant when compared to the other categories. But even here, Drugs and bad lifestyle are by far the #1 cost.
At the other extreme are us senior citizens. All of us are going to die. It takes a lot of money to keep us alive ... just a little while longer. But that is our society. Even with seniors, bad lifestyle takes an amazing percentage of the total cost.
In between are adults. This is the group with the largest gap between healthy and unhealthy. A small but growing faction have unhealthy lifestyles and amount to a disproportionate share of costs and an even bigger gap between what they pay in and what they get back.
Sorry if I focus on the cost. That is where my head is at this week.