Although we've never had any problems with worms, a couple of our alpacas do have reactions to the dreaded mange mite. We have a family of foxes who live in the hedges and copse which surrounds our paddocks and so aren't in a mite-free zone (who is?) I thought I'd share our mite experiences as it's always good to know how other people are tackling this problem.
One of our girls came back after being agisted with some bad mite damage, even though she had been given a 4 week course of ivermectin (2ml every week). At first I thought it would take ages to get on top of it but not so! Our vet (Hale in Chippenham) provided us with "witches brew", a topical mixture that includes ivermectin. After using this on our girl a few times (over her belly, armpits and legs) the pink skin returned and she's remained almost mite free since. I'm a firm believer in providing vits and minerals to alpacas susceptible to mite and we give her extra rations of camelibra. Maybe this helped too.
Then we have Jean-Luc. A neutered accoyo male who has very dense fleece. He's a real kicker and so for months last winter I just clipped his toenails on the ground where he stood. Then at shearing we noticed his ankles were really thick with hardened crusty skin - mite attack! He hadn't lost any fleece on his ankles and so I didn't realise this was happening. I felt really guilty, poor boy, that I hadn't properly checked his ankles over winter. Straight away we started him on a 4 week course of ivermectin and I started massaging his ankles with the witches brew. This was achieved by getting him to cush and then I asked my husband lie on him while I bravely grabbed his legs. As a proponent of cameldynamics I had wanted to avoid this level of man-handling but we had no choice, we had to treat those ankles. Of course Jean-Luc was absolutely fine and apart from a couple of warning spits he didn't mind. He's a gentle soul and we can do anything with him apart from grab his feet. Perhaps the fact that he has mite problems has exacerbated this kicking or even caused it. If his ankles are painful or itchy he probably doesn't want people grabbing them.
But the thing I found has really worked for Jean-Luc's hard, crusty skin was sudocrem - a wonder cream! This is the stuff that has softened the thick skin and is sticky enough to stay on in this wet weather. I've now stopped using witches brew, ivermectin and am just massaging sudocrem into his ankles every 2 weeks to protect them from mite and help keep his skin soft and healthy (plus it smells quite nice too).