Avian Diseases: New Castle Disease

• The following are study notes on various avian diseases

New Castle Disease (NDV)

• Pantropic acute contagious viral ailment affecting chickens, turkeys, pigeons, doves, pheasants, and psittacines.
• Zoonotic, causing erythema in the human eye.
• Caused by avian paramyxovirus serotype-1.
• Paramyxovirus also affects cattle and can cause human plaque.

Strains Affected

• Lentogenic strains cause mild or asymptomatic infections in chickens.
• Mesogenic strains cause disease and mortality in young chickens, reducing egg production in adults.
• Velogenic strains are viscerotropic, neurotropic, and lethal, causing 100% mortality in chickens of all ages.

Pathognomonic Lesions

• Manifests in three forms in chickens.
• Septicemia results in petechial hemorrhages in serous membranes (vasculitis in velogenic strains) and proventriculus and cecal tonsils which are pathognomonic.
• Respiratory form includes catarrhal tracheitis, pneumonia, conjunctivitis, and petechial hemorrhages on the heart and abdominal fat.
• Intestinal form involves focal hemorrhagic or necrotic enteritis (similar to coccidiosis) and enteritis with greenish diarrhea.
• Nervous form (encephalitis) leads to neuronal degeneration, gliosis, and perivascular lymphocytic cuffing.
• Recent cases show eosinophilic intranuclear and intracytoplasmic inclusions in conjunctiva, esophagus, lungs, brain, and adrenal ganglia of pheasants and brains of chickens with lentogenic strain.
• Eosinophilic intranuclear inclusions are found in hepatocytes in doves affected by lentogenic strain.

Avian Influenza (Fowl Plague)

• Viral disease known as fowl plague affects the respiratory, digestive, and/or nervous system of many bird species.
• H5 N2 strains cause severe drop in egg production.
• H5 N1 and H5 N8 strains are present in Egypt and highly pathogenic.
• H1N8, H8N7, H8N2 cause immune suppression but not active infection in Egypt.
• Caused by influenza virus type A of family orthomyxoviridae.
• Subtypes are determined by hemagglutinin (H) and neuraminidase (N) surface antigens.
• H5 (H5N2) and H7 (H7N1) subtypes are pathogenic, with H5N1 affecting chickens and humans.
• H1N1 (swine flu) affects turkeys, and H4N8, H4N6, and H3N8 are found in exotic birds.
• Clinical signs are affected by age, species, pathogenicity, and husbandry practices.

Pathognomonic Lesions

• Mild form includes catarrhal tracheitis, sinusitis, air sacculitis, conjunctivitis, and pneumonia.
• Systemic form lesions include hemorrhagic or septicemic signs.
• Cyanosis (purplish-blue coloration) and swelling of wattles and comb.
• Hemorrhages occur in skin of face, comb, wattles, trachea, intestine, proventriculus, and gizzard.
• Hemorrhages are present in muscles along the breastbone, heart, and abdominal fat.
• Clear straw-colored fluid accumulates in subcutaneous tissues, vasculitis.

Comparison of Newcastle Disease (NDV) and Avian Influenza (Fowl Plague)

Fowl Pox

• Infection causes decreased egg production, reduced growth, and blindness (cutaneous, respiratory, digestive, and ocular signs).
• Causes septicemic form in canaries with 70-90% mortality.
• Caused by Pox virus.
• Skin involvement starts from papule to vesicle to pustule to scape.
• Poultry has no pustule stage because no pus formation.
• Self-recovery but may become a diphtheria form if it affects the upper respiratory and digestive systems.
• Intra cytoplasmic inclusion bodies (Bollinger bodies)

Clinical Signs

• Starts as small whitish foci that develop into wart-like nodules around eyelids, head, beak, feet, legs, vent, and other featherless areas.
• Yellow diphtheritic membrane on mucous membranes of upper digestive and respiratory tracts, leading to difficulty breathing or swallowing.
• Mechanically to injured skin or by mosquitos

Gambaro

• Acute viral disease of young chickens (1-6 weeks) and secondary immunosuppression.
• Cause by Birnavirus
• Clinical Signs: diarrhea, vent picking, incoordination of movement
• Pathognomonic lesions: enlargement of Bursa and atrophy in later stages with caseated material
• Turkeys and ducks are sub-clinically infected.
• Hemorrhages in many parts of the body

Adeno Virus

• Includes various diseases with intra-nuclear inclusion bodies.

Inclusion Body Hepatitis

• Affects young chickens.
• Symptoms manifest 48 hours to 7 days post-infection.
• Intra-nuclear basophilic inclusion bodies mainly in liver, sometimes in spleen.
• Shows necrosis in liver.
• Kidney: Pale, swallow, hemorrhage

Turkey Viral Hepatitis

• Acute and highly contiguous disease is often subclinical.
• 25-100% Mortality possible.
• Isolated after 28 days on infection from bile, liver and blood

Hemorrhagic Enteritis in Turkey

• Bloody diarrhea & sudden death within 24 hours
• Septicemic lesions & enlarged mottled spleen
• Incubation 3-6 days.
• Isolated from spleen

Quail Bronchitis

• Acute highly contagious affect capitative & wild Quails
• Respiratory & nervous manifestations

Egg Drop Syndrome (EDS)

• Host: layer hen
• Flaccid oviduct
• Loss of shell
• 40% -100% decrease in egg production
• Endometritis

Infectious Bronchitis (IB)

• Contiguous viral disease affecting all ages.
• Respiratory symptoms.
• Drop in egg production and misshaped eggs.
• Coronavirus
• Affects upper respiratory tract, leading to inflammation (pharynx, sinusitis, laryngitis, bronchitis, not pneumonia).
• Has "nephrogenic form" that leads to nephritis and chalky material in ureter and renal pelvis.

Infectious Laryngotracheitis (ILT)

• Acute viral respiratory disease of primarily chickens and pheasants.
• Herpes viridae (DNA)
• Hemorrhagic laryngotracheitis with bloody plugs (cheesy plug in the tracheal lumen).
• Leads to death in about 70% of cases

Duck Virus Hepatitis

• Peracute viral infection of ducklings < 5 weeks.
• Picorna viridae cause.

Duck Viral Enteritis (Blue Peak)

• Acute viral disease of young and adult ducks, geese, and swans.
• High mortality, vascular damage, and nervous manifestation.
• Herpes virus (DNA) cause.

Marek's Disease

• Neoplastic viral disease that affects young chickens (until 5 months of age) and leads to great economic loss.
• Caused by a herpes virus (DNA).
• Several forms including: nervous, ocular, cutaneous, visceral, and mixed.

Diseases Caused by Avian Leucosis Sarcoma Virus

• Lymphoid leukosis
• Erythroblastosis
• Myelocytomatosis
• Osteomyosis
• Sporadic nephroblastoma and hemangioma
• Caused by oncorna virus

Lymphoid Leukosis (Big Liver Disease)

• Affects semi-mature and mature chickens (after 4 months).
• Gradual onset and persistent low mortality.
• Affects old age 14:36 weeks till 2 years.
• Liver is very large and can palpate from outside.
• Lymphoid Leucosis , erythroblastosis and myeloid leucosis are highly pathogenic

Avian lymphoid leucosis vs Marek's disease