Leeches feed solely on the blood of hosts and suck blood to many fold increase their size. They then detach and fall off. Blood loss caused by sucking and subsequent hemorrhage due to the anti-coagulant nature of the bite can leave animals weak and anemic. Occasionally leeches enter and attach within the nasal cavity or pharyngeal mucosa. In the Himalayan area the leach is by far the most common external parasite of buffalo and people.
Chickens are the most practical method of control.
Birds will wait at the trail side for buffalo to return from pasture and will then, with great excitement, pick leeches off the buffalo's legs, backs and ears. Leaches have been suspected of transferring the FMD virus. In Egypt, disease was observed at the end of the clover grazing period and characterized by irratitive bronchitis associated with the adult worms. Young calves are more susceptible and often deaths can result. Lack of cleanliness, environmental stress and climatic conditions all encourage the spread of these parasites.