47. Diseases caused by astroviruses.

Question 1

Astroviruses: Summary of the family

Answer 1

Astroviridae family

• Mamastrovirus genus
• Avastrovirus genus

Ø Envelope; ssRNA

Question 2

Diseases caused by Astroviruses: Notable diseases

Answer 2

1. Avian Nephritis
2. Duck Hepatitis
3. Astrovirus disease of Turkey

Question 3

Astrovirus: Mamastrovirus - Summary

Answer 3

• Human; Swine; Cattle; Cat
• Gastroenteritis

Question 4

Astrovirus: Avastrovirus - Summary

Answer 4

• Chicken astrovirus: Avian nephritis 1
• Duck Astrovirus
• Turkey Astrovirus

Question 5

Astrovirus: Avian nephritis - Occurance

Answer 5

Japan; USA; Europe; N. Zealand

Question 6

Astrovirus: Avian nephritis - Transmission

Answer 6

Faeces

Question 7

Astrovirus: Avian nephritis - Epidemiology

Answer 7

• Only chickens are susceptible
• Infection can occur in all ages
• Mortality: 1-10% in the first week

Question 8

Astrovirus: Avian nephritis - Pathogenesis

Answer 8

PO infection → Replicate in gut epithelium → Viraemia →

• Kidney: Epithelial cells of proximal tubules

Question 9

Astrovirus: Avian Nephritis - CSx

Answer 9

Seen in the first 4 weeks of life (more severe in young)

• Acute: Non-specific; General CSx; Diarrhoea; ↓ Weight gain
• Death

Question 10

Astrovirus: Avian Nephritis - Pathology

Answer 10

• Enteritis
• Nephrosis; Interstitial nephritis
• Chronic: Visceral urate deposition

Question 11

Astrovirus: Avian Nephritis - Dx

Answer 11

Epidemiology; CSx; Pathology; Histology

• Direct: RT-PCR; IF; IHC; Isolation
• Indirect: ELISA; VN; IF

Question 12

Astrovirus: Avian Nephritis - DDx

Answer 12

Nephropathogenic strains of infectious bronchitis

Question 13

Astrovirus: Avian Nephritis - Prevention

Answer 13

• Epidemiological measures
• Ø Vaccine available

Question 14

Astrovirus: Duck Hepatitis - CSx

Answer 14

Same as DVH caused by Picornavirus

Seen in young duckings

• Peracute: Large-scale death within hours
• Acute: Depression; Lethargy; Ataxia; Spasmodic padding; Death

Question 15

Astrovirus: Duck Hepatitis - Pathology

Answer 15

Same as DVH caused by Picornavirus

• Liver: Enlarged; Yellow; Dystrophy; Necrosis; Haemorrhage
• Spleen: Enlarged; Mottled
• Kidney: Swollen; Plethoric; Nephrosis

Question 16

Astrovirus: Duck Hepatitis - Dx

Answer 16

Same as DVH caused by Picornavirus

• Epidemiology; CSx; Pathology; Histopathology
• Direct: PCR; IF; Isolation
• Indirect: VN; ELISA

Question 17

Astrovirus: Duck Hepatitis - Prevention

Answer 17

Same as DVH caused by Picornavirus

• Epidemiological measures → Isolation at 4 weeks old
• Vaccine:
  
  • Inactivated: Layers → Booster
  • Attenuated:
    
    • ​Layers & Day-old ducklings
    • 7 Weeks old; 2-3 weeks before laying
  • Attenuated + Inactivated vaccination

Question 18

Astrovirus Disease of Turkey: Summary

• CSx
• Prevention

Answer 18

• Two Serotypes; Widespread
• CSx: Diarrhoea in 1-5 week-old animals
• Prevention: Epidemiological measures

Question 19

Astrovirus Disease of Turkey: Dx

Answer 19

Same as Avian Nephritis

Epidemiology; CSx; Pathology; Histology

• Direct: RT-PCR; IF; IHC; Isolation
• Indirect: ELISA; VN; IF