Salmonella Carriers?

[Navotifarm]

If the chickens can stay healthy enough that they continue to lay eggs but the eggs contain salmonella the extent they are killing people, are the workers getting sick? Or have they built up an immunity? Or might they be carriers of salmonella? Obviously these being factory-production egg houses, almost all aspects are mechanized but there must be workers somewhere in the operation. So I am wondering about them.
I'm also thinking ahead to next spring when, if I am still here, I would order newly-hatched chicks. How will I know next year's egg layers won't be bringing salmonella into my nice fresh "organic" eggs?