Top 10 Poultry Part 1

What are common respiratory signs of Newcastle disease?

Gasping, sneezing, coughing, and facial edema.

What is the key etiological agent of Newcastle disease?

RNA avian paramyxovirus-1 (APV1 or PMV-1).

List some clinical signs associated with Marek's disease.

Sciatic nerve paralysis, 'grey eye', decreased growth rate, and decreased egg production.

What is the primary diagnostic method for Marek's disease?

Virus isolation and PCR for viral DNA in lymphoid tumors.

What type of virus causes high-pathogenicity avian influenza (HPAI)?

Orthomyxovirus, influenza type A.

Classic clinical signs of HPAI.

Peracute death, prostration, cyanosis of head appendages, diarrhea, neurologic signs.

What preventative measures are recommended for HPAI?

Autogenous vaccination and strict biosecurity.

How is infectious laryngotracheitis transmitted?

Horizontally through aerosol and fomites.

What are the clinical signs of infectious bronchitis in young birds?

Acute onset upper and lower respiratory signs such as sneezing and coughing.

What is the etiological agent of infectious bronchitis?

RNA coronavirus.

What is a notable characteristic of Marek's disease?

It is a lymphoproliferative disease caused by an oncogenic lymphotrophic alphaherpesvirus.

What happens to egg production in birds affected by Newcastle disease?

Decreased egg production with thin shells and watery albumen.

How can Newcastle disease spread quickly among flocks?

Through aerosol exposure and poor management practices.

What are some features that differentiate low-pathogenicity AI from high-pathogenicity AI?

Low-pathogenicity often shows mild signs, while high-pathogenicity causes severe, rapid onset symptoms.

What is the significance of having 'wrinkled eggs' in poultry?

It indicates a case of infectious bronchitis.

What is the role of supportive care in managing avian diseases?

To help alleviate symptoms while the birds recover or provide care pending depopulation.

What is the relationship between Marek's disease and vertical transmission of the virus?

No vertical transmission occurs; it spreads horizontally, mainly through inhalation.

Which strains of Newcastle disease are reportable in the USA?

Mesogenic and velogenic Newcastle diseases.

What can happen to recovered chickens from infectious laryngotracheitis?

They can become lifelong carriers and shed the virus when stressed.

Newcastle disease clinical presentation?

High mortality rate.

Acute onset of severe respiratory and/or NS and/or GI signs:

1. Respiratory signs:

   • Gasping, sneezing, coughing

   • Facial edema (square head)

   • Reddened low eyelid (over lymphoid patch)

2. Neurologic signs:

   • Paralysis, tremors, droopy wings

   • Torticollis, circling

   • Bright and alert despite severe neurologic deficits

3. GI signs: watery, green diarrhea

4. Sometimes sudden death

5. Decreased egg production with thin shells and watery albumen

Newcastle diz etiology?

RNA avian paramyxovirus 1 (APV1 or PMV 1)

Newcastle disease Dx?

1. Gold standard is virus isolation

   • Dead birds - lung, kidney, GI tract

   • Live birds - nasopharyngeal and tracheal exudate swabs

2. RT PCR for pathotyping and genotyping

3. Intracerebral pathogenicity index - inoculate day old chicks to determine virulence

4. Hemagglutination positive

Necropsy findings Newcastle diz?

Almost pathognomonic - multifocal necrosis, hemorrhagic intestinal mucosa (esp. at lymphoid foci - cecal tonsils)

Newcastle diz Tx?

None, cull all birds

Newcastle prevention?

1. Good management practices, spreads quickly through facility via aerosol exposure

2. Indoor operations better, outdoor flocks at higher risk

3. Vaccines in countries where virulent virus disease outbreaks occur

Newcastle disease virus strains?

APV1 labeled depending on how fast they kill chick embryos at innoculation:

1. Lentogenic (slow), used in vaccines and not reportable

2. Mesogenic (medium)

3. Velogenic (fast), further divided into

   • Viscerotropic GI velogenic Newcastle disease

   • Neurotropic (brain) velogenic Newcastle diz

CS vary with strain

What determines the Newcastle diz strains?

Surface glycoproteins - hemagglutinin-neurominidazse and fusion

What can newcastle diz cause in humans?

Transitory conjunctivitis

Marek’s disease CS?

Based on which organ/tissue T-Ly infiltrate:

1. Sciatic nerve paralysis (one leg forward, one backwards)

2. Grey eye (due to lymphocytic infiltration of the eye)

3. Young chicken (2-5mos)

4. Decreased growth rate and egg production

5. Enlarged feather follicles (cause for condemnation)

Cause of Marek’s disease?

Oncogenic lymphotrophic alphaherpes virus (genus Mardivirus). Virus causes lymphoproliferative diz/neoplasia in chickens.

Silent recovered chickens are lifelong reservoirs.

Mareks Dx?

1. Virus isolation, PCR (for viral DNA in lymphoid tissues), AGID

2. Histopath and immunohistochemistry

Necropsy Marek’s?

1. Enlarged peripheral nerves (esp. sciatic)

2. Lymphoid tumors in liver, spleen, gonads, hearts, lung, kidney, muscle and proventriculus

3. Bursa is rarely affected and usually atrophic (distinguishes from lymphoid leukosis)

Mareck’s Tx and prevention?

No tx, supportive care in pet poultry. Prophylaxis - vaccinate in ovo or day old chicks decreases virus shedding

How is Marek’s transmitted?

No vertical transmission; horizontal is mainly via inhalation of aerosolized chicken dander and can travel on wind between flocks.

Avian influenza CS?

Depends on the pathogenicity/strain

Low pathogenic AI: often subclinical

1. Mild to moderate RS

2. Poor weight gain

3. Egg drop

High pathogenicity AI: fowl plague

1. Peracute death, prostration

2. Cyanosis of head appendages, petechiation in viscera, oral/nasal bloody discharge

3. Diarrhea

4. NS

5. Hemorrhages of the limbs

6. Spreads rapidly

AI vause?

Orthomyxovirus, influenza type A.

AI Dx?

1. Virus isolation in eggs from clinical samples with rRT-PCR for typing

2. Hemagglutination +

3. Hemagglutinin and neuraminidase typing and subtyping by inhibition test using antisera

ILT Cs?

1. Acute outbreak of gasping, coughing, conjunctivitis, dyspnea, depression

2. ± Bloodstained beaks in chickens under 4 weeks

3. Decreased egg production

4. Mortality variable, often high

5. Chronic: poor weight gain in broilers

6. Latent infection in survivors, can recrudesce when birds are stresses

ILT Etiology?

Gallid herpesvirus I

ILT necropsy and histopath.?

Blood, mucus, caseous exudate or hollow cast in trachea. See intranuclear inclusion bodies.

ILT Dx?

1. In clinical cases virus isolation, PCR

2. Screen flocks with ELISA or virus neutralization serologic tests

ILT Tx?

No Tx. Immediately vaccinate adults during outbreaks, prevent with biosecurity and vaccination.

IB CS?

Youngest birds:

1. Acute onset of upper (sneezing, conjunctivitis, swelling) and

2. Lower (rales, coughing, dyspnea) respiratory signs

Breeders & layers:

1. Sharp decrease in egg production

2. Misshapen or wrinkled egg shells

Variable mortality, almost 100% morbidity

IB Etiology?

RNA coronavirus. Some strains cause reproductive issues, some are nephotrophic.

IB necropsy?

White urates in renal tubules

IB Dx?

1. Negative hemagglutination reaction

2. Virus isolation in chick embryo

3. Paired serology

IB Tx?

Non, supportive case

1. ABx for secondary infections

2. Prophylaxis

   • Vaccines

   • Strict biosecurity