Help Kitten Losing Fur

I am reposting this as I put it in the wrong spot


My SIL just called me and she has a litter of 3 kittens, they are about 3-4 weeks old and all seemed healthy until today.

One of them is now losing all of it's fur, she called the vet and told her that kitten must have fleas, she does not see any, I told her to call my vet and have them look at the little guy.

Has anyone had this happen before?

IMO fleas don't make them loose fur, but ringworm might. I'd have the vet look at them ASAP - ringworm is contagious!