Poultry Diseases

Blackhead in turkeys

Blackhead disease in turkeys is very debilitating. It is primarily an acute or chronic disease of young turkeys. The correct name for the condition is histomoniasis. Histomoniasis affects peafowl, guinea fowl, pheasants and chickens as well as turkeys. It is transmitted by a microscopic protozoan named Histomonas meleagridis.

Blackhead in turkeysCredit: Turkey Gobbler

There is severe liver and caecum damage in infected turkeys and, if left untreated, the bird will usually die. On death, the head of the bird may become very dark hence the name. Blackhead can cause considerable losses in turkey flocks, especially among young birds of from 6 to 16 weeks.

Outbreaks are generally more severe in wet seasons and more common in spring and autumn.

Transmission of the Disease

Transmission of the disease is most often via the eggs of a second parasite, the caecal worm which is found in chickens and turkeys. Earthworms which happen to eat the caecal worm eggs may also pass on the disease. The H. meleagridis may stay dormant in the earthworm for up to a year but once the infected earthworm is eaten by a turkey the life cycle continues. Less common is the acquisition of the disease directly from the droppings of infected birds.

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Symptoms include:

  • general debility – loss of appetite leading to loss of weight
  • drowsy, dull, huddled appearance – often stand apart from other birds
  • ruffled plumage
  • increased thirst
  • diarrhoea – droppings may be sulphur coloured, foamy and contains traces of blood.

There is generally stunted growth, poor utilisation of food and finally death.


Generally, prevention involves not running turkeys with other poultry, and not running turkey poults on the same ground as adult turkeys. This is extremely important. If a worker is caring for both turkeys and chickens, cross-contamination between the two must be avoided and absolute cleanliness observed. The bugs can remain in the ground for up to three years. Exposure to the worms can be reduced by using wire or slatted floors. Wild birds such as pheasant and grouse may act as carriers.

Sound hygienic practices and litter management will help prevent the build up of organisms in the soil. Move feeders, waterers and roosts from time to time.

Blackhead disease is a serious disease and it is good practice to establish a routine of preventative treatment.

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Dimetridazole is commonly added to drinking water or feed to control outbreaks. Isolate sick birds. Burn or bury dead birds. If burying carcasses, be sure to bury them deeply. Cleanse and disinfect all equipment. And spread quick lime in the pen.

Flocks should be wormed every 8 to 12 weeks. Levamisole is one of the more efficient wormers.

Blackhead can be a serious problem in turkey flocks and every effort taken to avoid an outbreak will be well worth while.

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