I can think of two right off the bat, cholera and cryptosporidium
Biological
Many dieases occur from improper food safety and sanitation like food poisoning and salamona(water).
100% of illnesses are caused by virus because im a doctor and i should know.
Tuberculosis, inactive Meningitis, and Hansen's disease are some of the illnesses that Rifampin can be used to treat. Rifampin is an antibiotic and is used to treat illnesses caused by bacterial infection.
ringworm
The most common illnesses were scurvy, which is caused when you don't have enough vitamin C, dehydration, when you don't drink enough water, starvation, diseases, and the deadly heat on the ship.
pellagra
scurvy
Take an antibiotic.
That would have to be through water retention then, which can be caused by certain medications and illnesses. Not really something to aim for.
depression and neurosis
deaths, tragedy's, illnesses, and damage