The 26-year-old striker had a stomach bug and he's also struggling with a suspected hamstring injury.
As a result, he hasn't been able to train properly ahead of this weekend's clash away to the Super Eagles of Nigeria.
Baxter is concerned that the France-based attacker might not be able to feature against the 2013 Africa Cup of Nations champions, but said he will sit down with his technical team to see how this affects his team selection.
"The staff have managed our injuries very well. The only concern we have at this moment is Kermit Erasmus‚" Baxter told the media at the FNB Stadium on Wednesday.
"Kermit has had a stomach bug and because of that he's lost a lot of fluids and been getting cramps‚ and has got a little hamstring feeling‚ and we don't know if it's a cramp or a hamstring. It's a slight one‚ but it's a concern. He may not make the full session today," he continued.
"That's the only concern we've got left going to Nigeria. We'll manage him and see how he goes and that may affect my selection and it may not, but I think the lads have done very well in difficult circumstances," added Baxter.