I got a sign saying my MacBook air might have 5 viruses?

It showed me a sign saying that my MacBook Air might have (5) viruses and it prompted me to download MacKeeper. My friend downloaded it and her computer slowed down until she removed it completely. Is there a way I can check for viruses without downloading anything?

Added (1). Please answer it's the newest MacBook Air I've only had it 2 weeks and seriously don't want any viruses! I haven't downloaded anything on it by the way except Minecraft and MacKeeper, both of which I deleted as soon as I got them. There are no traces of them on my computer

Added (2). The sign popped up on my homepage, but when I clicked the top of it, it was labeled Safari in the top left corner of the screen.

Added (3). I didn't click the link on the sign, only the grey top part that there's on the top of every MacBook app

Added (4). What about the anti-virus software NetNanny? My Mum's friend downloaded it on her son's MacBook and nothing has happened to it.

Phoebe 07.11.2015

If you are reading ads on the side of webpages then these are scams just trying to make you download useless programs or even viruses. I use avg for windows not sure about ios

Dean 08.11.2015

It is a SCAM.

Prometheus 08.11.2015

There are no viruses that will infect OS X. Running anti-virus software on a Mac will cause problems not solve them. MacKeeper is a scam and should not be allowed anywhere near a Mac.

http://rixstep.com/2/20130621,00.shtml

http://www.macworld.co.uk/how-to/mac-software/how-remove-mac-antivirus-software-mackeeper-refund-3612033/

Duncan 08.11.2015

If you don't presently have an antivirus, don't you find it suspicious to get a virus detection warning?

I can't know if you do have viruses or not but I can tell you that fake virus warnings are amongst the most effective hoaxes online and will most likely worsen your situation.

UPDATE: Based on your updates, I'm wondering if your computer might still have traces of MacKeeper even if you don't see it.

http://applehelpwriter.com/2011/09/21/how-to-uninstall-mackeeper-malware/ could help you complete the cleanup process.

juliepelletier 08.11.2015

MacKeeper is a scam and might have actually put viruses on your computer. You need to run a different anti-virus program to see if you now have any trojans or root-kits on your computer.

tvandmusicfan 08.11.2015