46. Diseases of farm animals caused by hepatitis E virus.

Question 1

Hepatitis E Ethiology?

Answer 1

Hepatitis E

Etiology

• Hepeviridae, Orthohepevirus genus, Orthohepevirus A, C
• +ssRNA, 40nm icosahedral, non-enveloped
• Good resistance

‣ pH resistant

‣ 70℃ for 5 minutes but cannot stand cooling

• Biological properties

‣ Stenoxen ➝ Zoonotic

‣ Good antigenicity

• Diagnostics

‣ RT-PCR

‣ Isolation on cell culture is difficult

‣ ELISA

‣ WB

Question 2

Epidemiology?

Answer 2

Epidemiology

• Poor sanitary regions: human ➝ human, contaminated water transmits
• Developed countries: zoonotic genotypes

‣ Animal ➝ animal through faeces

‣ Animal ➝ human

๏ Direct contact with infected animal and/or its faeces

๏ meat, liver and raw meat products of infected animal

๏ Vegetables (salads), seafood contaminated with faeces/infected meat

Question 3

Pathogenesis?

Answer 3

Pathogenesis

- Animals

‣ Infection per os

‣ Virus replication: liver, shedding in faeces

‣ Viraemia ➝ meat during slaughter, extrahepatic replication

‣ Clinical signs, gross pathology lesions are absent (reproduction problems)

- Human

‣ Infection per os

‣ Virus replication: liver, shedding in faeces

‣ Viraemia

‣ Clinical signs

๏ Acute: subclinical or mild (Hepatitis A) symptoms or fatal outcome

๏ Chronic: extrahepatic symptoms ➝ neurologica signs

๏ Pregnancy: > 20% lethality in 3rd trimester

Question 4

Diagnostics and treatment of Hepatitis E?

Answer 4

Diagnostics

• Direct virus detection using faeces, liver, serum ➝ PCR
• Indirect virus detection ➝ ELISA, WB

Treatment

• Animals: not an option
• Human: supportive care ➝ acute hepatitis

Question 5

Prevention of Hepatitis E?

Answer 5

Prevention

• Animal/stable hygiene (faeces)
• Natural infection ➝ recovery ➝ seroconversion/maternal immunity (slaughter)
• Personal and kitchen hygiene, avoid the consumption of raw pork (products)
• Vaccine: clinical trials, human (to prevent/control epidemics by sewage)
• Significance: Zoonosis

‣ Potentially fatal infection

‣ Food safety

‣ Epidemiological and administration rules are not existing

Question 6

Chicken big liver and spleen disease epidemiology?

Answer 6

Chicken big liver and spleen disease ➝ ZOONOTIC

• Orthohepevirus B

Epidemiology

• Zoonosis
• Chickens (broiler parents in lay)
• Over 24 weeks of age

Question 7

Pathogenesis of Chicken big liver and spleen disease?

Answer 7

Pathogenesis

• Per os infection ➝ faecal contamination of drinking water

‣ Primary virus replication: intestinal mucosa epithel lymphatic tissue

‣ Viraemia

‣ Replication in liver and spleen ➝ clinical signs and pathology

‣ Shedding by faeces

Question 8

Clinical signs of Chicken big liver and spleen disease?

Answer 8

Clinical signs

• Chronic udder production or egg drops of up to 20%
• Anaemia
• Premature moulting
• Mortality: up to 1% /week for 3-4 weeks (normally only 0.25%)

Question 9

Pathology of Chicken big liver and spleen disease?

Answer 9

Pathology

• Enlarged liver, sometimes with subcapsular haemorrhage
• Enlarged spleen (over 1g/kg, often with pale foci)
• Not typical: lung congestion, ovarian regression, yolk peritonitis, pale foci and haemorrhages in pancreas

Question 10

Diagnosis and prevention of Chicken big liver and spleen disease?

Answer 10

Diagnosis

• RT-PCR
• qRT-PCR (direct)
• AGID
• ELISA (indirect)

Prevention

• Treatment: not an option (supportive care)
• Hygiene of drinking water
• General epidemiological measures