Chirurgeon's Log, XIV Legio

While traveling up the Via Lugdunensis on the way to Lugdunum, the party came across the remains of a Roman Army bivouac. Most of it was destroyed but under the collapsed canvas of the medical tent, they found the log of the Legion's chief medical officer, its Chirurgeon. The text of the log is below:

XX Quintilis MMXCVIII First clash with enemy forces. Small-scale confrontation. Casualties: XXXVII wounded, XI dead. Note: III of the wounded appear to have contracted unknown disease. Wounds resist all attempts at healing. Healing Salve ineffective. Augur’s attempts to use healing spells also failed. Outcome: Infected soldiers sent south to the nearest waystation for extended care. XXII Quintilis MMXCVIII Second battle – larger confrontation. Legion has apparently stopped advancing. Casualties: CXXVIII wounded. Number dead unknown, still to be tallied. Battle ongoing. Notes:

XXX more cases of illness that resist all attempts at healing.

Symptoms: Victims present low-grade fever. Skin slightly red as if from mild sunburn. Loss of appetite. Inability to keep food down.

Pathology: Unknown. Will question soldiers to determine pattern.

XXIII Quintilis MMXCVIII Second battle – concluded. Legion has withdrawn to regroup. Additional Casualties: CIII wounded. Number dead still to be determined, believed to be several hundred. Reports of many captured, number indeterminate. Notes:

XIII new cases with the same healing-resistant sickness. Symptoms agree with previous observation.

XXX existing cases, new symptoms: Hair loss. Increased fever. Skin has taken on a deeper red hue. Vomiting, lack of appetite. Inexplicable weight loss. Spells ineffective.

Pathology: Wounded soldiers who do not exhibit symptoms claim two types of enemies, one larger and blue-skinned in color, one smaller and red-skinned in color. All LIII cases with the incurable disease were stricken by the blue-skinned enemies.

XXV Quntilis MMXCVIII Sounds of battle to the north. Medical camp being prepared for defense. Cases:

Prior cases: LIII soldiers with illness continue to become progressively worse. No effective treatment. Death highly probable within the next day or so, beginning with the earliest cases.

New cases: Most wounded who had not become ill sent back to the front after treatment. XIII more serious cases withheld for observation. These now complain of chest pains and also lack appetite. No external cause visible.

Speculation: Cause may be related to…