Dragonfever

I am convinced the Gods gave us this virus. It is the most annoying virus I have ever seen in my entire life, and pretty much every dragon has caught it. Dragonfever doesn't last long, but those who have it do struggle plenty.

Symptoms

The most common symptom of dragonfever is an inability to fly. Well, for dragons with wings. Those with dragonfever will also experience strong sneezes, some set alight and can occasionally cause forest fires. Now getting set on fire by firesneezes from dragonfever is painful; I have first-hand experience.
This virus occurs mostly in the summers, and is caused by excess pollen being released which interferes with dragon's systems.

Treatment

The simplest treatment for dragonfever is to leave the dragon alone, and keep it from other dragons. Dragonfever is transmitted through prolonged contact between an infected dragon and an uninfected dragon of similar species, so keeping the infected dragon away will prevent it spreading and the virus will eventually die.
To soothe the symptoms, douse the dragon in water. Large waterbaths are perfect, and focus on the head of the dragon. One waterbath won't rid the dragon of the virus entirely, but a waterbath a day for about a week or two should do the trick. Have fun trying to get a fire dragon to have a waterbath.

Transmission

A highly communicable disease, dragonfever is commonly spread between those of the same (or similar) species. So, bad news for those with ranches of floradrakes in the height of summer.
Transmission between different species that aren't closely related is uncommon, but not unheard of. In fact, when the same dragons are in constant close contact with each other, it become much easier for dragonfever to be passed along - why, nobody really knows. A lot about dragonfever is unknown, since it is a hard virus to study, constantly changing so no medical treatment will work forever.