There are things that happen like ear infections. Happened to a friend on his way from San Diego
. Not fun to say the least. And yes he was hallucinating after a bit.
You can also pick up things unknowingly prior to leaving, which take a few days to incubate into a full fledged illness. But when they do, you wind
up stupid sick, & way offshore
. Or you might have the misfortune to succumb to something like pnemonia, or similar, due to snotty weather
for extended periods. Yes, the bacteria need to be present. But the beginning "seeds" of some illnesses are either always present, or can linger around for ages onboard, or on you, until your internal defenses are down enough for them to bite you.
I mentioned the book, & the mental aspects of things, as tiredness plays a huge role in any illness when one's on shore, & it's easy to get rest in relatively high quantities, & quality. But when you're out sailing that ain't often possible. And the lack of rest thing switches to a logarythmic scale when short/singlehanding. Which is where the mental & emotional bits fit in.
Plus knowing how best to get quality rest as is specific to you, is a highly bankable item in illness & injury prevention. When Dame Ellen did her record
run RTW on Castorama/B&Q they had her wired up to all kinds of bio-monitoring gear
. Including to monitor
her "sleep bank account". So that at times her shore team would strongly suggest rest (weather permitting). With much of this also being based on prior determinations on what worked best in terms of sleep, & food
time cycles for optimum rejuvination & sailing performance.
Ditto with astronauts, specialized sports disciplines, military units, etc., etc. Where the cost of failure is beyond high.
Edit: One option that comes to mind is to kick out a drogue
or sea anchor
for 72 until the worst has passed, just as you'd do if the storm was external instead of internal. The sticking point being about keeping a lookout for other vessels. It would be a trade
off it seems ???