Doesn't need to be recent. I've seen some people with RATs installed for over a year or two before they noticed any symptoms. Corporations in particularly can get a RAT but rather than merely screwing around or making outright blackmailing attempts, they may have intentions such as stealing intellectual property or source code etc, we describe these as APTs (Advanced Persistent Threats).
Best recommendations are the age old ones:
Keep antivirus up to date
Don't click on links
Use HTTPS for logins
Use a password manager
Enable 2 factor authentication where possible
View emails using plaintext only, DO NOT view allowing HTML or scripts
My personal recommendation on anti-virus would be BitDefender which comes at a fairly reasonable price and a quick Google search can reveal some discount codes. If you are on a corporate network, get rid of conventional anti-virus and try SentinelOne out for network protection, I am doing a review of it now and it is really impressing me thus far, outclassing anything else I have used in corporate environments. For servers etc, look up GRSecurity - nothing else really compares (Nope, not even SELinux or AppArmour before somebody says it).