11. Avian diseases caused by circoviruses, chicken infectious anaemia.

Question 1

Avian Circovirus diseases ?

Answer 1

Avian circovirus diseases

• Beak and feather disease virus
• Canary circovirus
• Duck circovirus
• Zebra finch corcovirus
• Goose circovirus
• Gull circovirus
• Pigeon circovirus
• Raven circovirus
• Starling circovirus
• Swan circovirus
• Psittacine beak and feather disease virus (BFDV)
• Pigeon circovirus (PiCV)
• Goose circovirus (GoCV)

Question 2

Ethiology?

Answer 2

Etiology

• Circoviridae, Circovirus genus
• Clinics, pathology and histology as in PMWS
• Cytoplasmic inclusion bodies in infected cells ➝ macrophages, lymphocytes
• Lymphocyte depletion
• High morbidity, low mortality
• Growing resistance with age
• Immune suppression and secondary infections

Question 3

BFDV Psittachine beak and feather disease?

Answer 3

BFDV ʹ Psittacine beak and feather disease

BFD (Beak and feather disease)

• Australia, cockatoo
• Young birds under 3 years old
• Old and new world parrots
• Horizontal and vertical transmission
• In dividing cells: feather follicles, cell division areas of beak and claws

Acute

• Lethargy, anorexia, respiratory signs, weight loss, vomiting, diarrhoea
• Death within 2-4 weeks because of secondary infections
• Frequently before the typical feather and beak deformities

Chronic

• Typical lesions sometimes obvious only after melting, loss of feathers, feather and beak deformities
• Can go on for years or die within 1 year because of secondary infections
• Surviving birds are persistent carriers and shed the virus

Question 4

Pigeon Circovirus?

Answer 4

Pigeon circovirus (PiCV)

• North America, later all around world
• Mostly between 1-12 months
• Clinical signs: lethargy, anorexia, beak, feather and claw deformities
• Only rarely: retarded growth
• Race performance decreases
• Horizontal and vertical transmission
• Acute:
• Similar to BFD
• Mortality between 2-5 days
• Mortality in young pigeons ➝ 0-100%
• Cells are destroyed in spleen, thymus and bursa

Question 5

Goose CV?

Answer 5

Goose CV

Goose circovirus (GoCV)

• 1999
• From 1 week old
• Clinical signs
• Retarded growth
• Decreased production
• Feather formation
• Higher mortality
• Confections with Rimerella anatipestifer, Aspergillus fumigatus
• Pathology
• Lymphocyte depletion and cystic atrophy in the bursa of Fabrici
• Globular or botryoid, basophilic intracytoplasmic inclusions within macrophages in the bursa of circovirus infected goose

Question 6

Chicken anaemia virus info?

Answer 6

Anelloviridae family

Chicken anaemia virus

• Anaemia + immune suppression
• Only chickens (up to 1 month old)
• Single serotype with minor genetic variations

Etiology

• Anelloviridae (Gyrovirus genus)
• VP1-3 proteins
• VP1: capsid proteins
• VP1 + VP2 (phosphatase) VN Ab induction
• VP3 apoptosis (activated T, B monocyte, blood cell progenitors)
• Resistant ➝ 80℃ in half hour

Question 7

Chicken Anaemia virus epidemiology?

Answer 7

Epidemiology

• Vertical ➝ sperm, egg
• Horizontal ➝ direct contact, faeces, fomites
• Shedding with egg and faeces up to 2 months (maximum at week 2)
• Infection

‣ Below 3 weeks ➝ disease/severe

‣ Over 3 weeks ➝ no disease/mild

Question 8

Clinical signs of Chicken Anaemia Virus?

Answer 8

Clinical signs

Clinical

• Anaemia-dermatitis syndrome
• Vertical transmission
• Horizontal after hatching
• 10-14 day old chickens
• Rare

Subclinical

• Resistance with age
• Horizontal transmission
• Frequent
• Decreases performance of productivity

Clinical signs

• Usually up to 1 month of age, after that gradual decline
• Incubation: 7-10 days, death within days
• Not typical, anorexia, lethargy, paleness, depression

Question 9

Pathogenesis of Chicken infectious anaemia?

Answer 9

Pathogenesis

• Per os ➝ intestine (respiratory) ➝ viraemia ➝ bone marrow ➝ anaemia, IS
• Per os ➝ intestine (respiratory) ➝ viraemia ➝ thymus (IS), bursa (IS), other organs

Question 10

Pathology and histopathology of Chicken Infectious anaemia?

Answer 10

Pathology

• Anaemia, oedema
• Haemorrhages in gizzard and proventriculus
• Thymus: atrophy
• Bursa: atrophy, mild or medium between 10-14 days of age, after vertical transmission
• Bone marrow: yellowish
• Liver: necrotic areas
• Histopathology: myeloid and lymphoid cells destroyed

Question 11

Diagnostics and differential diagnostics of Chicken infectious anaemia?

Answer 11

Diagnosis

• Symptoms and pathology only suspicion
• Virus isolation on lymphoid cells
• IF, PCR, hybridisation
• VN, ELISA, IP, ilF

Differential diagnosis

• Infectious bursitis ➝ diarrhoea, more expanded haemorrhages, thymus less affected
• Newcastle disease
• Avian influenza
• Viral inclusion body hepatitis ➝ adenovirus, necrosis, haemorrhages, pancreas, liver and spleen

Question 12

CAV vaccines?

Answer 12

Protection

• General rules
• Vaccination of hens (12-15 weeks old)

Vaccine

• Inactivated virulent
• Live, moderately attenuated
• By drinking (Cux-1) between 12-16 weeks old (younger ones can get disease)
• IM, SC (26P4) minimum 2 weeks old, 6 weeks before laying