47. Diseases caused by astroviruses.

Question 1

Diseases caused by astroviruses?

Answer 1

Diseases caused by astroviruses

General characterisation of astroviruses

• Astroviridae family

• Mamastrovirus genus ➝ human, swine, cat ➝ gastroenteritis, mainly in winter
• Avastrovirus genus

‣ Chicken astrovirus ➝ Avian nephritis 2 and 2

‣ Duck astrovirus

‣ Turkey astrovirus

• 28-30 nm, icosahedral, not enveloped
• 7-8 kb +ssRNA
• Resists against pH 3 or 60℃ for 5 minutes

Question 2

Avian Nephritis Occurrence aetiology epidemiology?

Answer 2

Avian nephritis

Occurrence:

• Japan, US, Europe, New Zealand, widespread, Hungary since 1970s, widespread seropositivity

Aetiology:

• Avian nephritis 1 (& 2) virus, virulence variants

Epidemiology

• Shedding in faeces
• Only chickens are susceptible in ANY AGE GROUP

Mortality:

• 1-10% in chicken in the 1st week
• If immunosuppressive agents
• more severe signs

Question 3

Avian Nephritis Pathogenesis?

Answer 3

Pathogenesis

1. Per os infection
2. Gut epithelium ➝ replication
3. Viraemia
4. Kidney ➝ epithelial cells of proximal tubules

Question 4

Avian Nephritis Clinical signs?

Answer 4

Clinical signs

• Clinical signs in first 4 weeks of life
• In young animals more severe
• Day-old chicken

‣ Acute ➝ not specific, general clinical signs (generally from day 3)

‣ Diarrhoea, kidney lesions

‣ Decreased weight gain, growth retardation

• In chronic cases ➝ visceral rate deposit and death

Question 5

Avian Nephritis Pathology?

Answer 5

Pathology:

• Enteritis
• Nephrosis, interstitial nephritis ➝ swelling, paleness, urate deposition
• In chronic cases ➝ rate deposition

Question 6

Diagnosis of

Answer 6

Diagnosis

• Epidemiology ʹ clinical signs ʹ pathology
• Histology: kidney
• Detection of virus: RT-PCR, IF, IHC, isolation of the virus (difficult, primary chicken embryo kidney)
• Detection of Abs: ELISA, VN, iIF

Question 7

Differentation diagnosis and prevention control of avian nephritis?

Answer 7

Differentiation diagnosis:

• nephropathogenic strains of infectious bronchitis

Prevention, control

• General epidemiological methods
• No vaccines

Question 8

Duck Hepatitis?

Answer 8

Duck hepatitis

• 2 serotypes
• Clinical signs, post mortem lesions ➝ like duck hepatitis caused by picornavirus
• Diagnosis, prevention ➝ like duck hepatitis caused by picornavirus

Question 9

Astroviruses diseases of turkey?

Answer 9

Astrovirus disease of turkey

• 2 serotypes
• Widespread
• Clinical signs: diarrhoea in 1-5 week old animals
• Diagnosis: like avian nephritis
• Prevention: general epidemiological measures