I think it is a system problem with laundry or dishwashing machines. Somewhere down the line, pressure and/or temperature is not being maintained adequately to kill the bugs, so they live on from voyage to voyage. Look specifically at napkins and silverware.
I doubt seriously that there is a waterline/sewage issue, but stranger things have happened.
Silverware and plates with water spots mean the plate temperature did not reach 161 degrees for at least 15 seconds if a dishwasher was used. Chlorine disenfectants can be used but health officials prefer hot water dishwashers. Water temperature in a dishwashing facility must reach 181 degrees to get the plate temperature to 161 degrees.