78. Avian metapneumovirus infections.

Question 1

History, Occurence ?

Answer 1

Avian metapneumovirus

• Paramyxoviridae, Pneumovirinae, Metapneumovirus genus, Avian metapneumovirus
• History, occurrence
• 1979-80 TRT turkey S. Africa, 1980- SHS Europe, Middle East
• 1986-1988 description of the virus, 1990- live vaccines, APV S. America
• Free: Australia, NZ, Canada (?)
• Worldwide ʹ 4 subtypes:
• A & B: Europe
• C: America
• D: dunno

Question 2

Diseases?

Answer 2

Diseases

• A) Turkey rhinotracheitis (TRT)
• B) Chicken rhinotracheitis (ART) ʹ different from SHS
• C) Duck rhinotracheitis
• D) Swollen head syndrome (SHS)

Question 3

Epizootiology?

Answer 3

Epizootiology

• Susceptible: turkey, chicken, duck etc.
• Morbid: 100% turkey, 10% hen
• Long distance transmission: wild birds
• All ages susceptible (but more frequent 4-9 weeks)
• Local transmission: horizontal ʹ air-borne, vertical ʹ no evidence (but found in oviduct and
• affects egg quality/production), quick spread in the flock
• Affecting factors:
• management, environment
• lentogenic NDV, E coli, B avium, Ornitho rhinotr, C psitacci, Mycoplasma

Question 4

Pathogenesis?

Answer 4

Pathogenesis

• Airborne infection, droplet infection
• replicate in oral/airways mucosa
• affects cilia
• (ciliostasis, inflammation, epithel damage)
• predispose to 2dary infections
• Viremia:
• reach oviduct
• inflammation, decrease egg production/quality, shell discoloured
• (white/spots)
• Immune reaction: good antigen Æ stops carrying
• Yolk immunity is not sufficiently effective for day old, but see delayed convalescence
• Co-infections are frequent (E. coli, M. gallisepticum, O. rhinotracheale)

Question 5

Clinical signs?

Answer 5

Clinical signs

• Turkey rhinotracheitis (TRT) Lacrimation, nasal discharge, cough, sneeze, sinusitis
• Egg production decrease by 70% and quality
• Complications can make more severe!
• Avian rhintotracheitis (ART)
• 2 mth chick
• Milder resp than turkey, sometimes Æ SHS
• Egg production/quality worse, white pigments
• Swollen head syndrome (SHS)
• With e coli
• Lacrimation, nasal discharge, sneeze
• Extended head edema, SC alatti edema
• Ocular edema, sinusitis
• Duck rhinotracheitis (DRT) Resp signs, egg production drop (not as common)

Question 6

Lesions?

Answer 6

Lesions

• Pulmonary oedema, discharge in the airways , suffocation
• Oviduct degenerations ʹ histo
• Swollen mucous membranes of upper respiratory tract, damage cilia
• Inclusion bodies

Question 7

Diagnosis?

Answer 7

Diagnosis:

• Need lab! Many with similar signs!
• Virus: RT-PCR, IF, ELISA, isolation hard
• Atb: ELISA, VN

Question 8

DD AND treatment?

Answer 8

DD:

• NDV,
• CRD,
• Haemophilus,
• O. rhinotracheale,
• infectious bronchitis,
• E coli,
• Avian Bordetella,
• Mycoplasma,
• Chlamydia
• can complicate but also can give such signs alone

Treatment: Antibiotics ʹ for complications

Question 9

Prevention?

Answer 9

Prevention:

• management, hygiene, vaccinations
• Vaccines: live attenuated ʹ A & B serotype, spray/drinking/conjunctival ʹ day old/later
• 4-6 wks
• inactivated ʹ for revaccinations, breeding flocks, after vaccinated with live
• (d 1, 4-6 weeks) can give inactivated 16-20 weeks just before laying
• good immunity yolk