If you only use the CF card to store picture files the DC will be OK.
DCs are not like PCs. Almost all PCs run the same OS, thus are susceptible to the same virus programs. PC viruses will not infect DCs unless they start to run Windows OS.
DCs run on firmware. So they are almost impossible to be infected by a virus. Even if there is, a virus has to be written specifically to target a certain brand/model.
To get the virus into a DC, the only path I see possible is when the use performs a firmware upgrae. So someone can write a piece of virus that disguises itself as a firmware upgrade. When loaded, it can cause damages that can very well be irreversible.
To conclude, the concept of a computer virus does not really apply to DCs, unless the day comes when DCs are running PC type of OS.
I wouldn't be surprised if it happens in future. There are phones running mirco$oft crapware. There are commands you can send to most siemens (non-mirco$haft) phones which can totally disable them (yes, I have tried it with my wife's phone, and she is verrry pi**ed off with me). Cameras like the Kodak DC series are programmable... in fact you can write scripts which run at boot time.
My guess is that the number of infections would be quite small so people haven't (yet) bothered to write virii for this range of devices.