What should I do about my husband's parents who don't bathe or change their clothes EVER?

This is very hard to write, but it is the truth. I am currently visiting the city where my husband grew up in. His parents are elderly, and are not used to going anywhere. They have a huge family, but there is a problem. My in-laws are filthy people. They do not bathe, ever, and do not even use the air conditioning in their house. They live in complete squalor & filth. There are roaches everywhere in the house, even crawling over their utensils. I was horrified the first time I went. My husband has tried to get them to bathe, but they refuse. They have never liked bathing, so it isn't because they are old. My husband had a special shower stall built for them in their home, so they wouldn't have to climb over a tub. They won't use it. I am very concerned, because they both have foot fungus, and my husband brought me over to our apartment to stay for the weekend. They didn't even bring clothes to change into, nor any toothbrushes. The smell horrible. How can we get them to start having better personal Hygiene? How am I going to clean my carpet, and the futon where they slept from bugs? I am pretty sure they have lice, and carry bed bugs on them. It is a nightmare! The man even had a "sack" of eggs growing under his scrotum one time. His wife poked the sack, and the little bugs came out. True story we heard from his brother. None of my husband's family will do anything. I wasn't crazy about bringing them over. They've been wearing the same clothes & underwear for over a year now. I am not kidding.