I don't have any anti-virus or firewalls, I am just smart about it. I run a scan once a month, maybe... Just don't download things you don't know about. If you go to an image and it wants you to download it, something is fishy, you should be able to view an image via your browser...
The only virus I have every had was on my first computer when I was 8 years old....
More likely is that your PC is infested with all sorts of things you simply don't know about.
It is not possible to avoid the spyware, trojans, viruses, cookie malware and so on unless you only visit Creators Forum, Ship Simulator, Yahoo, Google, Microsoft and BBC.
The moment you stray oustide of the really good guys, you will be infected at some level. Absolutely guaranteed.
No amount of protesting will shake me from this view. I have been active in antiviral software for many years. Every time someone claims that they don't have antiviral software because they are "special" in some way, it turns out that they are infested.