The dash (hyphen pretending to be a dash) ought to be a period instead. The other errors are all about commas.
They started out as a group of ten. Within a week, they had lost two. They were hungry, dirty, tired, and weak. Food was scarce, and nerves were beginning to fray.
(Something I feel I ought to point out: although there are multiple uses of to be verbs in this sample, there is no use of passive voice. If you don’t want to take my word for it, try the “zombie test” on it. Can you add by zombies to the end of any of these sentences and have it make sense? No? Then it isn’t passive voice.)