Please help!! what happens if a horse drinks water that runs from a pigs pen where they have went bathroom?

Hi, ok I have been away for 2 wks. and had family taking care of my horses for me. Well when i came home my horses have been sick, there has been no new horses brought in. Well they have swollen abscessed lymph nodes, only 2 of them do the other one only have a cough when cinched up to ride, really confusing. the older one had a small cut on the side of her face i guess in the morning when they went up to feed her, then when they went up that night she had swollen abscessed lymph nodes that quick, and the other one had a bit of a runny nose and swollen abscessed glands he also had bug bites really bad under is chin. While i was away they tried to make things easier by hooking some kind of watering system and it runs from the pig pen watering tub onto the ground and down into the horse pasture. Was just wondering if that could have caused some sort of an infection with an already open wound. please no rude comments, i just would really like some help. Also i have 10 horses and those are the only 3 sick, the ones that have drank outta the water, the others are in seperate pastures, but nearby. thanks you...