During the civil war, more soldiers died of disease than died directly from bullets and cannon balls. Today we have antibiotics: chemicals that kill bacteria, but not humans. You probably took antibiotics if you had strep throat or pneumonia.
As you will see in the simulation to the right, when you take antibiotics, a few bacteria may be lightly immune. If they survive, a whole population of their offspring, some with even stronger immunity, can take hold. That is why doctors always warn you to finish taking antibiotics for the whole time period prescribed, even if you are feeling better. Antibiotic-resistant "superbugs" have become increasingly common.
But 80% of the antibiotics in the US actually go to farm livestock! That increases farm profits -- you can pack more animals into a crowded space-- but it greatly increases the chances of antibiotic resistance arising. Putting profits ahead of people and animals is an issue of social justice. You can help this issue just by checking the label on a package of meat or choosing to purchase a meal from a company that advertises antibiotic-free meat.
And you can help by educating yourself and others about antibiotic resistance. Try out this simulation. Click the green flag at top right to start. Clicking the space bar will deliver antibiotics. Experiment with your timing on how often you administer antibiotics, and see what happens when resistance appears. If you want to try changing this simulation you can modify it by clicking here.