You never hear about catching a headache from someone.
Viruses are known for causing cold symptoms or digestive tract symptoms, but are there any viruses that only cause headaches? I realize the other symptoms are more common defense mechanisms and that may play some role. Is a headache not as much of a defense mechanism and therefore not a common symptom by itself or is it more that the viruses don’t tend to attack that which would cause a headache?
Many sinus infections are viral, and they’ll most assuredly give you headaches. Influenza will often dehydrate the victim, and dehydration causes nasty headaches. As for viruses that cause only headaches (excluding computer viruses,) I have no info for you.
Thanks AskNott, but that is what I am specifically curious about is a virus that will cause nothing BUT a headache and why there isn’t such a thing, if there is not. I have thought of meningitis as the closest thing, but that usually gives you flu like symptoms as well.
viral encephalitis gives one HELL of a headache. Of course, you get fevers, visual changes, and nausea and vomiting to name a few other symptoms.
Why would you expect a virus to cause only a headache? The causes of headaches are many; there is no ‘headache’ site in the brain from which they all arise, from where one may stimulate a headache.
A headache is a very vague symptom. Headaches can be classified as “muscle tension”, “migraine”, “cluster”, “rebound”, and “sinus” to name only the more common types, each with a different cause. Throw in “subarachnoid hemorrhage”, “hormonal”, and “temporal arteritis” and you’ve still just scratched the surface as far as causes go. Again, all different pathology.
QtM, MD
I am a heavy coffee drinker and get some serious headaches when I stop drinking coffee - - Which I do at least once a year for at least a month because I take so much sugar in the coffee it ends up being my major source of calories. But when I stop taking coffee I get some serious headaches for a couple of days. I read these headaches are of the same type as migraines and they were being studied in an effort to find remedies for migraines.
Many of the symptoms of a viral infection are actually side-effects of our immune system fighting the infection, like swelling, sore throats, redness, etc, etc. If there were an infection that only caused headaches, that would be one strange immune system interaction. It’s possible it’s out there, but not likely, because it would have to behave very differently from viruses we know of today. Additionally, the epidemiology doesn’t really fit - headaches don’t tend to pass from person to person, usually.
Caffiene withdrawal (rebound) headaches share some similar physiologic features with migraines. However I would not tell a migraineur that you identify with them because you have caffiene withdrawal headaches. Imagine the difference between being savaged by a housecat and being savaged by Roy’s tiger. Or being savaged by an enraged migraineur! 
Thanks everyone. QtM, thanks for the detail. Smeghead - your answer put very simply what I was after - if it ever made sense for a virus to attack something that would cause the immune system to only respond with a headache. I know you generally don’t catch headaches from people - I just wondered if it was possibly going to be the next flu bug of the future or if it just didn’t make sense from an immune system response standpoint.