I barely remember this movie, but I know it is older. I believe it's set in Egypt in present (then) time. An archaeologist uncovers a scarab that attaches itself to people. Not sure what it does but I have a distinct memory of a guy hunching over in pain and it is digging it's legs into his chest.

The mummy, possibly?

I wonder if it might be Cronos? Which, however, is not set in Egypt.

I doubt this is it but the Exorcist? They uncover something and the guy has a heart attack right after that. Just in case.