Viral disease of many species of psittacines characterized by chronic feather and beak
dystrophy
– Acute immunosuppression and sudden death in young birds due to secondary bacterial
septicemia and fungal infections
Etiology: Psittacine circovirus, genus circovirus, family Circoviridae
Clinical signs: dystrophic feathers first noticed of the powder down, progress to contour
feathers, followed by primary, secondary tail and crest feathers, almost symmetrical
– Dystrophy of the beak
Lesions
– Gross: abnormal and loss of feathers, sloughing of claws, beak necrosis, necrosis of oral
mucosa, liver, bursa, thymus, etc.
– Microscopic: pterylitis and pulpitis associated with botryoid inclusions in macrophages,
also in bursa, bone marrow, thymus, beak, claws, liver, pancreas, thyroid, testes, etc.
Intranuclear inclusions in feather epithelium, intestine, esophagus, hepatocytes
Pigeons and doves
– Etilogy: Pigeon circovirus, genus circovirus
– feather dystrophy, exudate in bursa (due to bacterial infection), pterylitis, bursal
lymphoid depletion and intracytoplasmic circovirus inclusions in macrophages of bursa
of Fabricius, spleen, thymus, cecal tonsil, etc.
– secondary bacterial, parasitic, fungal and other concurrent viral infections common
Canaries and Finches
– Etiology: Canary circovirus, genus circovirus, family Circoviridae
– Feather dystrophy and characteristic circovirus inclusions in bursa of Fabricius in finches
Gulls and Geese are also susceptible to circovirus
– Circovirus inclusions in the bursa of Fabricius
s. Papovavirus
Two genera are known to cause disease in psittacines and passerines
– Papillomavirus
– Polyomavirus
Papillomavirus
– It has been associated with cutaneous papillomas in wild finches (Fringilla) and an
African Grey Parrot
– No virus has been associated with papillomas of cloaca, conjunctiva, tongue, larynx, oral
cavity, crop/esophagus, etc., in psittacines
Polyomavirus
Three groups, A, B and C
– Causes BUDGERIGAR FLEDGLING DISEASE (BFD)
One of the most common diseases of psittacines (disease of 90’s?) and passerines
Antibodies to BFDV been detected in chickens, but chickens are resistant to
infection
Etiology: polyomavirus, different strains such as psittacine, passerine, etc., may exist
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Variety of psittacines, finches, canaries, seed crackers and blue bills are
susceptible
Young psittacines are highly susceptible with very high mortality (30 - 100%),
also adults
Feather dystrophy in budgerigars, acute death, digestive, neurological, respiratory
signs, etc.
Lesions
Gross: variation among psittacines and also passerines
♦ In most of psittacines feather dystrophy, hemorrhages in skin, subcutis,
skeletal muscle, heart, intestine, liver enlarged and mottled red or with white
foci, splenomegaly, pale kidneys, ascites, lung congestion, pale carcass, etc.
♦ In passerines, liver enlarged and mottled white, serosal or subserosal
hemorrhage of intestine, pale myocardium, etc.
Microscopic: hemorrhages in various organs, necrosis in spleen, bursa, thymus
and bone marrow, midzonal or random necrosis in liver, myocarditis, enteritis,
nephritis, membranous glomerulopathy, pancreatitis, conjunctivitis,
encephalomyelitis, ganglionitis (spinal), etc.
♦ Bluish karyomegalic inclusions in various tissues; epidermis, feather follicle
epithelium, esophagus, kidney, macro/lympho of spleen, bursa, thymus, bone
marrow, liver, etc., hepatocytes, myocytes, endothelial cells, glial cells,
Purkinje cells, etc.
Buzzards and Falcons are also susceptible
– Goose hemorrhagic polyomavirus:
causes high mortality in 4-10 week old geese, 100 % mortality in one week-old geese
subcutaneous edema, ascites, hemorrhagic enteritis, nephritis and lymphoid necrosis
in bursa of Fabricius
t. Proventricular Dilation Disease (PDD)
A common chronic disease of psittacines
– Characterized by dilation of proventriculus, anorexia, regurgitation, passing of
undigested seeds in feces, diarrhea, neurological signs, loss of weight, etc.
Also been seen in a perigrine falcon, Canada geese, etc.
Etiology: not known, presumed to be a virus
Lesions
– Gross: dilated thin proventriculus in 70% of cases, distended duodenum, etc.
– Microscopic: lymphoplasmacytic ganglioneuritis of splanchnic nerves of
crop/esophagus, proventriculus, gizzard, intestine, adrenalitis, myocarditis, neuritis,
encephalomyelitis, choroiditis, etc. (see table 2)
u. Miscellaneous Viral Diseases
Turkey viral hepatitis
– Disease of young turkeys
– Etiology: Picorna-like virus
– Liver and pancreas with foci of necrosis and inflammation
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Viral arthritis
– Disease primarily of young chickens and turkeys
– Etiology: reovirus
– Joints enlarged with fluid, proliferative synovitis
Avian nephritis
– Highly contagious disease of chickens
– Etiology: Picornavirus (distantly related to Human A hepatitis virus)
– Nephritis and secondary visceral urate deposition
Hepadna virus (hepatitis B virus)
– Common in ducks, but no significant clinical disease or lesions
– also in swans and geese, no associated clinical disease
Hepatitis E virus
– Has been associated with hepatitis-splenomegaly syndrome in mature chickens
– Disease is called big liver and spleen disease in Australia
– Drop in egg production and increased mortality
– Periportal hepatitis, vasculitis, necrosis and hemorrhage in liver. Spleen with increased
number of MPS cells with amyloidosis frequently
Louping ill virus
– Red grouse are susceptible
Arboviruses
– WEST NILE VIRUS
Etiology: Flavivirus
First appeared in people in the US in NY city in 1999, flu-like symptoms, 7/61 died
About 14 orders and over 70 species of birds are susceptible but most severe in
crows, blue jays, geese, herons
others; pigeons, owl, kestrels, hawks, gulls, storks, magpie, bald eagle, ducks,
flamingos, macaw, cockatiels, cockatoo, parakeet, etc.
Chickens and turkeys are resistant to infection
clinical signs vary from sudden death to depression, weight loss, ataxia, tremors,
opisthotonus, impaired vision, etc.
gross: hemorrhages in brain, pale areas in the myocardium, enlarged spleen,
nephritis, hemorrhage and necrosis in the intestine
histo: primarily nonsuppurative encephalitis and myocarditis. Others include necrosis
in spleen, liver, pancreas, and enteritis, nephritis, adrenalitis and pulmonary
hemorrhage.
Virus widespread in many tissues but kidneys and brain are good for virus isolation
– EASTERN EQUINE ENCEPHALOMYELITIS VIRUS
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Causes neurological signs and encephalitis in pheasants, partridges, finches and
turkeys
In young turkeys and chickens, myocarditis, lymphoid necrosis in bursa and thymus
Hemorrhagic enteritis and splenic necrosis in emus
– WESTERN EQUINE ENCEPHALOMYELITIS VIRUS
Encephalitis, myocarditis, hemorrhagic leiomyositis of intestine associated with
vasculitis in emus
Encephalitis in pigeon and neurological signs in turkeys
– HIGHLAND J VIRUS:
Encephalitis and myocarditis in partridges and young turkeys
Associated with precipitous drop in egg production in turkeys
– ISRAEL TURKEY MENINGOENCEPHALITIS VIRUS
Encephalitis and myocardial necrosis in 10-12 week-old turkeys
– BUNYA VIRUS (Turlock-like):
Associated with encephalomyelitis and myocarditis in an ostrich chick
10. Parasitic diseases
Protozoa: coccidia, histomonas, cryptosporidia, sarcocystis, toxoplasma, atoxoplasma,
amoeba, microsporidia, trichomonas, leucocytozoon, malaria, haemoproteus, giardia,
cochlosoma, spironucleus (Hexamita), balantidium, trypanosomes, hemosporozoa,
besnoitia, chilomastix, caryospora, etc.
Nematodes: Ascarids, Capillaria, Syngamus, Tetrameres, Heterakis, Baylisascaris, etc.
Cestodes: Raillietina, Davainea, Hymenolepis, etc.
Trematodes: Prosthogonimus, Schistosomes, etc.
Arthropods: mites, fleas, lice, etc.
Protozoa
a. COCCIDIOSIS
Common disease of many species of birds caused by species of genera primarily Eimeria and
Isospora and are quite host specific
Chickens: disease of universal importance
– Eimeria tenella (ceca), E. acervulina (upper small int.), E. maxima and E. necatrix (mid
small intestine)
– Hemorrhagic, mucoid, necrotic, proliferative enteritis
– Numerous coccidia in different stages of development
Turkeys: common, lesions less severe than in chickens
– E. adenoides (ceca), E. meleagrimitis (mid small intestine)
– Mucoid enteritis, sometimes hemorrhagic and necrotic enteritis
Geese: E. truncata occurs in kidney
– Nephritis and urate deposits
– E. anseris causes enteritis
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Ducks: renal coccidia due to E. boschadis, etc.
Quail, partridges, and pheasants: various species of Eimeria causes enteritis
– In quail coccidiosis is commonly associated with ulcerative enteritis caused by
Clostridum colinum
Pigeons: E. labbeana causes enteritis
Psittacines:
– Species of Eimeria, E. dunsingi and Isospora can cause enteritis in budgerigars, lories,
parakeets, parrots, etc.
Passerines:
– Finches: Isospora lacazei has been associated with enteritis
Cranes:
– E. gruis and E. reichenowi causes granulomatous enteritis, hepatitis, splenitis,
pneumonia, myocarditis, etc. in whooping and sandhill cranes
b. HISTOMONIASIS
Also called black head, a common protozoal disease of turkeys and partridges
– Also in chickens, peafowl, quail, pheasants, rhea, etc.
Etiology: Histomonas meleagridis
– Cecal worm, Heterakis gallinarum and earth worms act as accessory hosts
Lesions: saucer shaped depressions or white foci in liver and fibrinonecrotic mucosa and
thickened wall of ceca
– Granulomatous hepatitis and typhlitis associated with spherical protozoa, 8 - 21 um in
diameter
– Nephritis, bursitis (bursa of Fabricius), pneumonia, proventriculitis, pneumonia,
peritonitis secondary to perforating typhlitis can be seen in turkeys
c. CRYPTOSPORIDIOSIS
Common protozoa of various species of birds
– Chickens, turkeys, quail, ratites, ducks, pheasants, peafowl, psittacines, passerines, etc.
C. baileyi, C. meleagridis and Cryptosporidium spp in Finches and probably others
Infect various body systems
– Cloaca, bursa of Fabricius and trachea most common
– Nasal cavity, sinus, bronchus, air sac, conjunctiva
– Proventriculus, intestine, ducts of pancreas, salivary and esophageal glands and bile duct
– Ureters, collecting tubules of kidney
Inflammation and hyperplasia of epithelium
d. SARCOCYSTOSIS
Systemic protozoal disease of psittacines caused by S. falcatula
– Opossum is the definitive host, cowbirds and grackles are intermediate hosts
– Old World psittacines highly susceptible
– Young new world psittacines, canaries, finches, pigeons are susceptible