Global InformationHistomoniasis information
| Histomoniasis | |
|---|---|
| Other names | Histomonosis, blackhead disease |
 | |
| Large, pale areas in the liver of a bird infected with Histomonas meleagridis | |
| Specialty | Veterinary medicine |
Histomoniasis is a commercially significant disease of poultry, particularly of chickens and turkeys, due to parasitic infection of a protozoan, Histomonas meleagridis. The protozoan is transmitted to the bird by the nematode parasite Heterakis gallinarum.[1][2] H. meleagridis resides within the eggs of H. gallinarum, so birds ingest the parasites along with contaminated soil or food.[3] Earthworms can also act as a paratenic host.
Histomonas meleagridis specifically infects the cecum and liver. Symptoms of the infection include lethargy, reduced appetite, poor growth, increased thirst, sulphur-yellow diarrhoea and dry, ruffled 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.
- ^ Lund EE, Chute AM, Wilkins GC (1975). "The wild turkey as a host for Heterakis gallinarum and Histomonas meleagridis". Journal of Wildlife Diseases. 11 (3): 376–381. doi:10.7589/0090-3558-11.3.376. PMID 1171270. S2CID 45359310.
- ^ Brener B, Tortelly R, Menezes RC, Muniz-Pereira LC, Pinto RM (2006). "Prevalence and pathology of the nematode Heterakis gallinarum, the trematode Paratanaisia bragai, and the protozoan Histomonas meleagridis in the turkey, Meleagris gallopavo". Memórias do Instituto Oswaldo Cruz. 101 (6): 677–681. doi:10.1590/s0074-02762006000600017. PMID 17072483.
- ^ a b McDougald, LR (1998). "Intestinal protozoa important to poultry". Poultry Science. 77 (8): 1156–8. doi:10.1093/ps/77.8.1156. PMID 9706082.
- ^ 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).
- ^ Miles, Gary D. Butcher and Richard D. (19 June 2015). "Intestinal Parasites in Backyard Chicken Flocks".
