Hmm...I have to check the lit on the symptoms before death...if the snake was previously asymptomatic.
Parasites are tricky...I'm more speaking about human pathogens and parasites... but a few that are known to cause no symptoms in humans are strongyloidosis, many species of whipworms and roundworms, and Entamoeba histolytica...Again sometimes even well known normally symptom triggering pathogens sometimes just don't cause external symptoms for the uncommon individual..human or otherwise. Some symptoms are so broad and general they are considered clinically insignificant...fever for instance.