Blackhead

Blackhead is an infectious disease of turkeys, chickens, and several wild birds. It is caused by a protozoan parasite named Histomonas meleagridas. The parasite attacks their intestines and liver, and causes darkening of the skin on the head and hence the disease is named blackhead. Several birds that have black heads are also called blackheads. Blakhead is also a plug of sebum in a hair follicle, which is oxidised and darkened.