PC Remote Control: Is there a possibility infecting each other with Virus, etc.?

I'm using TeamViewer to remotely access my mothers' PC.

the problem is, i dont know if her computer is already infected with viruses/spyware/etc.

when i remotely access her PC, is there a possibility that my computer will be infected with viruses/etc. and vice versa?

what set up should i change in our security set-up to prevent any infection ?

Mother PC security setup: Window Firewall+Avira.

thanks!