What should I do about my in-laws visit?

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 he is bringing them to stay in our small one bedroom apartment. They are going to sleep on our bed, with our clean linen, and they won't bathe! They literally stink, and my husband won't tell them anything. I want them to bathe everyday that they are there, but I don't it is going to be a battle. One time my father in law even had a roach egg growing on his scrotum. My mother in law popped it, and a bunch of little bugs crawled out. That is how dirty there people are! I am very scared they are going to infest our apartment with body lice. I don't know what to do, and I am stressed out beyond belief. My husband has done all he can do. None of his brothers, or sister give a crap about the condition they live in. They are used to it. I am going to have to spend a week with them in our apartment entertaining them, and smelling them. I feel so stressed out about this!