List of five major parasitic diseases of birds:- 1. Coceidiosis 2. Histomonosis 3. Ascaridiosis 4. Raillietinosis 5. Knemidokoptosis.
Parasitic Disease # 1. Coceidiosis:
Coccidiosis is a common protozoan disease in domestic birds and other fowl, characterized by enteritis and bloody diarrhoea. The intestinal tract is affected, with the exception of the renal coccidiosis in geese. Clinically, bloody faeces, ruffled feathers, anaemia, reduced head size and somnolence are observed.
The area around the vent is stained with blood. The infection is realized by a faecal-oral route. After ingestion of sporulated (infective) oocysts, sporozoites are released that enter asexual and sexual cycles of development resulting in the emergence of thousands of new oocysts in the intestines. Oocysts are distributed by faeces.
Soon, they sporulate and become infective for chickens. The intestinal lesions provoked by coccidia, are due to injury of the epithelial cells of the mucous coat where the parasites are developed and multiplied. The oocysts exist in the litter in premises and are distributed by clothes, shoes, dust, insects, etc.
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Pathoanatomically, dehydration and a high degree of anaemia of the body and viscera are discovered. The microscopic examination of a native preparation of intestinal content or superficial mucosal layer reveals a significant number of oocysts in one observation field.
Prevention:
The use of coccidiostatics with forages on a rotation basis is the most extensively used means. The immunization against coccidiosis with commercial vaccines is used in broiler breeder flocks. If the chickens are exposed to the natural effect of a moderate number of oocysts in their environment, they develop immunity to the respective parasitic species.
Parasitic Disease # 2. Histomonosis:
The histomonosis is a protozoan disease, caused by Histomonas meleagridis, and characterized by necrotizing lesions affecting the liver and the caeca. Clinically, sulfur-yellow coloured faeces and depression are observed. A characteristic feature is the blackening of the skin of the head (blackhead), due to cyanosis.
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Pathoanatomically, bilateral enlargement of caeca with thickening of walls is observed. The aetiological agent is Histomonas meleagridis, a polymorphic flagellate that is present as flagellate in caeca and as amoeba in tissues. The trophozoites survive for several hours in the environment but in eggs, they remain infective for more than a year.
Some wild birds serve as vectors. The caecal content is often mixed with blood. The main sources of infection are hens and chickens. The morbidity rate amounts to 90% and the mortality rate to 70%. In the liver, irregularly outlined coagulation necroses with various size and colour, are observed.
Diagnosis: It is made on the basis of the typical macroscopic lesions. When necessary, a histological study and phase-contrast microscopy of native preparations could be performed.
Parasitic Disease # 3. Ascaridiosis:
Ascaridiosis is one of the most prevalent helminthoses in fowl. It is caused by various species from the Ascaridia genus. The ascarids have a direct life cycle. Sometimes, it could involve paratenic hosts (earthworms).
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Infected birds are progressively emaciated, anaemic and sometimes diarrhoeic. Pathoanatomically, haemorrhages of various intensities are found out in intestinal mucosa, catarrhal haemorrhagic enteritis, and the parasites are also observed.
In cases of extensive invasion, the ascarids block the intestinal lumen and could cause a complete obstruction. The treatment and the control are realized through regular pathoanatomical and copro-ovoscopic studies and performance of therapeutic and protective dehelminthizations.
Parasitic Disease # 4. Raillietinosis:
Raillietinosis is a cestodosis characterized by diarrhoea (sometimes bloody) during the acute stage and emaciation to cachexia and anaemic during the chronic stage. It is caused by some representatives of the Raillietina genus that parasitize in various areas of the small intestine.
The usual intermediate hosts are ants or other insects. Pathoanatomically, haemorrhages with various intensities in the intestinal mucosa, catarrhal haemorrhagic enteritis and the parasites are found out throughout the gross examination. The treatment and the control are done by dehelminthization of all birds in the affected farm.
Parasitic Disease # 5. Knemidokoptosis:
Knemidokoptosis, known also as scaly or chalky legs, is characterized by the appearance of extensive, rough and hard crusts on the featherless part of the legs. Adult birds are generally affected (hens, turkeys, pheasants, exotic birds).
It is caused by Knemido koptesmutans. The lesions are secondary to an inflammatory reaction, in which the thickening of the cutaneous epidermis together with released exudate forms the crusts on legs. The infection occurs by contact between birds. The control is done by isolation of affected birds, leg bathing with warm acaricide solution and warm vegetable oil that helps the decrustation.