>>13463774Werewolves and vampires are fictional, but if those were real many people would want to catch that communicable disease ... the sort-of eternal life of vampires and whatnot.
So yeah OP, a disease that is beneficial in some way could do very well. Making it odd that there aren't any - at least for communicable diseases.
Sickle cell anemia (sca) is what you get if you have two haemoglobin-b genes; detrimental. But having one h-b gene gives some malaria protection. A hereditary disease therefore, sca, yet a gene variant that as such can be beneficial.
