The latest treatment for mites in alpacas, I have come across and have yet to try is from Ohio State University (OSU).
Where the injectable route doesn't appear to be effective and from my entry yesterday we can pretty much say that it very rarely is a workable solution on its own, then OSU recommend the following.
If the skin is really scaly use a shampoo containing benzoyl peroxide as it really helps to loosen up the crusts and lift them off, making the skin much more supple. If there is then evidence of bacterial infection (pustules and the like) then something like Etiderm is a good choice being both antibacterial as well as keratoytic.
(Keratolytic therapy thins the skin on and around the lesion. The medicine causes the outer layer of the skin to get loose and shed.)
Along with this OSU will sometimes also give a shot of Bose ( for the vitamin E) and supplement with Vita E powder and sometimes Zinpro for the zinc which is often low in these cases.
OSU have also used Frontline spray for some cases with success. This is when it is used for 3-4 weeks in conjunction with ivomec. But this is a more expensive approach.
Both yesterdays solution and today's were provided to me by Dr Tara Timpson of Crater Animal Clinic here in Southern Oregon.
So there are three options to talk about with your vet who will then help you select a solution that is effective for your herd.
If you know of any other treatments that are effective against alpaca mites please let me know.
Adrian Stewart