Histomoniasis

Source: Wikipedia, the free encyclopedia.
Histomoniasis
Other namesHistomonosis, blackhead disease
Large, pale areas in the liver of a bird infected with Histomonas meleagridis
SpecialtyVeterinary medicine

Histomoniasis is a commercially significant

paratenic
host.

Histomonas meleagridis specifically infects the

feathers. The head may become cyanotic (bluish in colour), hence the common name of the disease, blackhead disease; thus the name 'blackhead' is in all possibility a misnomer for discoloration.[4] The disease carries a high mortality rate, and is particularly highly fatal in poultry, and less in other birds. Currently, no prescription drug is approved to treat this disease.[3]

Poultry (especially free-ranging) and wild birds commonly harbor a number of parasitic worms with only mild health problems from them. Turkeys are much more susceptible to getting blackhead than are chickens. Thus, chickens can be infected carriers for a long time because they are not removed or medicated by their owners, and they do not die or stop eating/defecating. H. gallinarum eggs can remain infective in soil for four years, a high risk of transmitting blackhead to turkeys remains if they graze areas with chicken feces[5] in this time frame.

Symptoms

Symptoms appear within 7–12 days after infection and include depression, reduced appetite, poor growth, increased thirst, sulphur-yellow diarrhoea, listlessness, drooping wings, and unkempt feathers. Young birds have a more

morbidity, moderate mortality, and extensive culling, leading to overall poor flock performance.[3] Concurrence of Salmonella typhmurium and E. coli was found to cause high mortality in broiler chickens.[6]

Cause

A protozoan

digestive system of the host, the protozoan is moved to the cecum along with the eggs of H. gallinarum.[8]

Transmission and pathology

The disease causing agent, Histomonas meliagridis, is transmitted in the eggs of the worm Heterakis gallinarum.[8] Once in the environment, the eggs are carried by earthworms. When the worms are eaten and the eggs hatch in the ceca, the pathogen is released.[9] Bird to bird transmission can also occur from cloacal drinking [10]

Visible signs of this disease are cyanosis of the head (hence, “blackhead”) and sulfur-yellow diarrhea. The pathogen causes lesions on the ceca and the liver. The ceca experience ulcerations, enlargement, and caseous masses start to form inside of them. The liver develops round, haemorrhagic, 1-2 centimeter oci that have caseous cores.[9]

Diagnosis

Histomoniasis is characterized by blackhead in birds. H. meleagridis is released in the cecum where the eggs of the nematode undergo larval development. The parasite migrates to the

kidneys.[11]

Prevention and treatment

Currently, no therapeutic

ppm, and well tolerated by turkeys.[16]

History

The disease was initially discovered in Rhode Island in the year 1893. Soon after, it was shown to have devastating effects on the turkey industry, especially in New England, dropping production from 11 million birds in 1890 to 6.6 million in 1900. However, improvements in turkey management have curbed the effects of this disease. It has since spread across the globe.[8] It has been found in turkeys, chickens, guinea fowl, and other game birds.[9] Bobwhite quail can also be infected.[17]

References

  1. S2CID 45359310.Open access icon
  2. PMID 17072483.Open access icon
  3. ^
    PMID 9706082.Open access icon
  4. ^ Davidson DR, Doster GL. Blackhead Disease does not Really Cause Black Heads. Archived 2011-05-16 at the Wayback Machine NWTF Wilflife Bulletin No. 25, pp. 25(1-4).
  5. ^ Miles, Gary D. Butcher and Richard D. (19 June 2015). "Intestinal Parasites in Backyard Chicken Flocks".
  6. S2CID 25256520
    .
  7. PMID 12887212
    .
  8. ^
    S2CID 43031620
    .
  9. ^ a b c Dinev, Ivan. "Histomonosis - Diseases of Poultry". The Poultry Site.
  10. ^ McDougald, Larry R, PhD. The Poultry Site: Histomonosis. Retrieved from http://www.thepoultrysite.com/articles/1285/control-of-blackhead-disease/
  11. S2CID 41063366
    .
  12. ^ McDougald, Larry R, PhD. The Poultry Site: Histomonosis. Retrieved from http://www.thepoultrysite.com/publications/6/diseases-of-poultry/207/histomonosis/
  13. PMID 19664306
    .
  14. S2CID 25315125
    .
  15. ^ U.S. Food and Drug Administration (April 1, 2015). "FDA Announces Pending Withdrawal of Approval of Nitarsone".
  16. S2CID 24953201
    .
  17. S2CID 31323766
    .

External links
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