From what I understand, these were primarily dizziness and migraines.
Adam Ewing believes he is infected with a parasitic worm. The Gusana coco cervello. (Worm, Coconut, Brain) translated as "Coconut Brain Worm).
Dr. Henry Goose: Ah, there you are.
Adam Ewing: What happened?
[as Adam tries to get up Goose pushes him back on his bed]
Dr. Henry Goose: It is as I suspected; Gusano Coco Cervello.
[Goose shows Adam an image of the worm from his book]
Dr. Henry Goose: Better known as the Polynesian worm. Once saw a man's brain after the worm had finished him...maggoty cauliflower. Ooph. But have no fear, this particular devil and I are well acquainted.
[Goose mixes some medicine and drops some into Adam's mouth]
In the book, Adam is quotes:
“My Ailment is a parasite, Gusano coco cervello. This Worm is endemic throughout both Melanesia & Polynesia, but has been known to science only these last ten years. It breeds in the stinking canals of Batavia, doubtless the port of my own infection. Ingested, it voyages through the host’s blood vessels to the brain’s cerebellum anterior. (Hence my migraines and dizziness.) Ensconced in the brain, it enters a gestation phase. ‘You are a realist, Adam,’ Henry told me, ‘so your pills shall be unsugared. Once the Parasite’s larvae hatch, the victim’s brain becomes a maggoty cauliflower. Putrescent gasses cause the victim’s eardrums & eyeballs to protrude until they pop, releasing a cloud of Gusano coco cervello spores. ‘
Thus reads my death sentence…”
- From The Pacific Journal of Adam Ewing from Cloud Atlas by David Mitchell.