Lice don't even quicken my heart rate anymore, not after having rats absolutely infested with them.
Lice don't move around very much, and they are very slow. They only live off their hosts for a few hours and then they will die. In order to contract lice, you have to be in very close proximity to the person/animal infected.
Rat lice are species specific, as has already been mentioned, they will not even cross over to mice who have their own species of lice.
I remember when Phoenix and Horus came to me from the THS, they were covered in lice like I have never seen before. It was more apparent on Horus, because he had dark fur, that every single hair on his body was covered in nits. It was awful. Horus' fur looked shiny, but it was actually dead dull, because of the lice infestation, and the nits just made it look shiny. They had been treating them, according to the shelter, but whatever they were using wasn't doing the trick.
I gave them one dose of Revolution and that was all she wrote! They were gone in no time, and Horus had a beautiful healthy coat back within two weeks. I have heard that rats can have a bad reaction to being injected with Ivermectin, so I will not ever go that route. I would only use that stuff topically. I have used horse wormer paste, way back before I learned about Revolution, but I will not use that again because of the risks vs Revolution.
I don't clean the cage at the same time as giving the treatment. I treat them with the Revolution, wait 24 hours, and then clean the cage thoroughly. That way, the adult ones that have dropped off them because of the treatment can be cleaned away.
I freerange buggy carrying rats last, so that nobody is in the freerange area directly after them. I have purchased the bird mite spray and used it to spray the area after freeranging. I never, EVER use that stuff directly on the animal, only on the area they freerange. That way, the spray can work on killing anyone in the freerange area before they next day when the rats are out again. I wipe down the area the next day so they don't get any of the residual spray on their toes, but I don't think that it is that potent 24 hours later.
Here is a picture of Horus that I took with him covered in nits...