Rodney has been diagnosed with Legionnaires' disease. Now that he is getting treatment for the disease he should start improving. Carol must have had a milder case of it. At least she didn't get pneumonia, but she is still not feeling up to par. They may have contacted it through the air conditioning at the Hotel that they stayed in during the family reunion trip. They didn't stay in the same room and they seem to be the only ones in the family that caught it.
The Hotel was in Texarkana, Arkansas in case you want to book a room there. I don't know the name of the Hotel.