Updates 45 (couldn't think of anything witty)

[Mamorien]

Explicit Discussion of Infectious Disease, Explicit Mention of Infant Illness

Time for A Thing of Vikings' winter cours!

Much like birds and bats, dragons have an aggressively active immune system in comparison to humans, and for much the same reasons.  Simply put, for a flying animal, an inflammatory response in the face of an infection is often a death sentence, so there is significant selective pressure for immune systems which can deal with an infectious agent quickly.  In the case of draconic immune systems, this goes one step further, as an unchecked infection of the dragon's hydrocarbon organ system can have literally explosive results. 
As such, while there are diseases that can affect dragons—especially ones that target the dragon's symbiotic bacteria—on the whole, a typical dragon's immune system resembles a military base swarming with constant armed patrols and barriers of razor-tipped wire.  A disease attempting to stage an infection of such a system needs to be extremely effective at intrusion, starting with thwarting the symbiotic bacteria in the salivary glands that are the immune system's first line of defense.  These bacteria not only help dragons create the biofilm mucuses that aid with fire resistance in the otherwise vulnerable soft tissues of their mouths and throats, they are primed to help their host with fighting off any microscopic invaders who attempt to get a toehold in the tissues of the mouth and gut, as the bacteria secrete a variety of antibiotics, antivirals and antitoxins—this last being significantly important in breeds whose breath can have toxic byproducts—all of which are refined by selective pressures on the symbiotic bacteria for maximum efficaciousness. 
That being said, there is still a range within the greater dragon species in terms of immunological effectiveness.  If a typical dragon's immunological response is akin to a military base on high alert, then those dragons whose diets expose them to biological hazards up the ante, to being more akin to a forward artillery base with active minefields and with gunnery crews in possession of itchy trigger fingers.  The saliva of many Boulder-class dragons are rich in antitoxins, including ones that can encapsulate elements such as arsenic, rendering them relatively harmless and ready for expulsion in the dragon's fecal waste (although this is not a universal defense, as the radiological poisonings from the ingestions of radioactive materials and the cancers caused by the ingestion of asbestos both demonstrate). Meanwhile, Buffalords, the premier example of a draconic immune system taken to extremes, consider botulism to be a spice in the vein of how humans consider mint or caffeine, raw pufferfish is seen as a tasty snack, and cyanide is a treat.

At Turpan, in the Taklamakan, Drago and the Kagan play hwigi and talk like friends, and we readers learn the Kagan's name at last. In the Healer's Hut of the Hooligans, Ruffnut hears allusion to a cure for the hundred days' cough and wonders why the others have preemptively given up on looking for it. After Mass in the chapel, Wulfhild opens talks with one of the other resident Christians. In Gobber's new smithy over on Eigg, Hiccup works on his latest invention, with a little help from his old mentor. Back in the Healer's Hut, Ruffnut finds no cure mentioned in the official records, but is reminded of something that might be effective. Crossing Normandy on dragon-back, Fishwings gets the full impact of the accusation Lopsides threw at her a chapter ago. And we close on Berk, in Gothi's hut, where Ruff finds what she's looking for and seeks a way to turn the information into something useful...

https://archiveofourown.org/works/104089...s/68303581