Pliny, Aetius, Dioscorides, Scribonius-Largus, Celsus, Oribasius, Paulus Aegineta, and others, describe such cases.
Bartholinus speaks of a Neapolitan prince who, while hunting, quenched his thirst in a brook, putting his mouth in the running water.

In this way he swallowed a leech, which subsequently caused annoying hemorrhage from the mouth.

Timaeus mentions a child of five who swallowed several leeches, and who died of abdominal pains, hemorrhage, and convulsions.
Rhodius, Riverius, and Zwinger make similar observations.

According to Baron Larrey the French soldiers in Napoleon's Egyptian campaign occasionally swallowed leeches.

Grandchamp and Duval have commented on curious observations of leeches in the digestive tract.