Immunosuppressive Diseases

in Poultry

االمراض المثبطة للمناعة فى الدواجن

By

Mohamed Hossany Negm

Senior Technical Support Specialist

and Marketing

Master’s Degree, Poultry Science, very good

TEL:00201123223874

Faculty of Agriculture Zagazig University

Immunosuppressive Disease-General Indicators-

Increased incidence of complicated

respiratory disease

Increased E. coli problems

Increased condemnations-- airsacculitis and

Septicemia/Toxemia

Failure to resolve vaccine reactions

Failure to respond to medication

Immunosuppressive Disease-General Indicators-

Increased mortality and poor performance

Decreased serologic response to

vaccination

Increased incidence of secondary disease

Gangrenous dermatitis

Inclusion body hepatitis

Necrotic enteritis

Immunosuppressive Disease-Specific Indicators-

Early/permanent damage to bursa of Fabricius

<2 weeks of age

Early/permanent damage to thymus in young

chickens

General lymphoid cell depletion

Failure to respond immunologically to antigens

Vaccines

Experimental antigens- sheep red blood cells,

Brucella abortus

Immunosuppressive Disease-Specific Indicators-

Failure to respond to vaccination as

evidenced by lack of resistance to field

challenge following challenge

Failure to mount a cell-mediated immune

response (CMI)

Fowl Pox, ILT

Inability to clear bacteria from the

bloodstream following IV inoculation

Immunosuppression-Confusing Factors-

Introduction of new pathogen for which

current vaccines are not protective or

available.

Variant Infectious Bronchitis

Variant Infectious Bursal Disease

Very virulent Infectious Bursal Disease

Variant Mycoplasmas

Etc.

Immunosuppression-Confusing Factors-

Inappropriate or ineffective vaccination programs

Use of virulent vaccine

– ‘hot’ Gumboro vaccine

Maternal and/or vaccine titer to low at vaccination

Improper vaccination techniques

– Fine spray versus coarse spray

– Respiratory vaccines-IBV, NDV

– Gumboro vaccines

Misuse of vaccines that cause Immunosuppression or

interfere with immune response

Immunosuppression-Confusing Factors-

Development of resistance to commonly used antibiotics

Environmental factors

Sanitation

Biosecurity

Ventilation

Bird density

Down time between flocks

Breed differences

Avian Immune System

Bursa of Fabricius (B-lymphocytes)

Thymus (T-lymphocytes)

Liver

Spleen

Bone marrow

Lymphoid cell aggregates

Blood

LYMPHOID

PATCH

CECAL

TONSILS

HARDERIAN

GLAND

THYMUS

HEART

SPLEEN

BONE

MARROW

BURSA of

FABRICIUS

YOLK OR

YOLK

REMNANT

AVIAN IMMUNITY

Factors Affecting Function of

Immune System

Innate resistance

Age

Sex

Physiology

Genetics

Factors Affecting Function of

Immune System

Environment

Air quality

Temperature

Stress

Nutrition

Sanitation in hatchery and grow-out

Biosecurity

Infectious Diseases

Factors Affecting Function of

Immune System

Diet

Formulation

– Profound effect on function of immune system

Dietary toxins

– Mycotoxins

– Biogenic Ammines

– Rancid fat

Infectious Diseases that Affect the

Immune System

Infectious Bursal Disease

Chicken Anemia Virus

Marek’s Disease

Reovirus

Interactions

Infectious Bursal Disease

Clinical Form

Typically in birds 2.5-6 weeks of age

Classical and vvIBD virus strains- gelatinous

transudate on bursa of Fabricius, edema,

hemorrhage, followed by atrophy due to

lymphocyte destruction and depletion.

Mortality especially with vvIBD

Transitory immunosuppression

Infectious Bursal Disease

Subclinical Form

Occurs prior to 2 weeks of age

Characterized by atrophy of bursa without evidence of clinical disease

Most important form of disease in many parts of world, results in permanent and severe damage to bursa of Fabricius

The earlier the damage occurs to bursa of Fabricius, more severe the immunosuppression

Infectious Bursal Disease

Effects on immune responses to IBV, NDV

and ILT vaccines

NDV- decreased response to vaccination,

increased persistence of virus in trachea

IBV- reduced resistance to challenge,

increased virus persistence by several weeks

ILT- decreased response to vaccination, but

does not increase viral persistence

Effects of IBD Virus on Immune Response

Immune Response to NDV Vaccine following Infection with

IBDV at Different Ages

Treatment Mortality

IBDV

Challenge

NDV

Vaccine

NDV

Challenge

# dead/total

1 day 28 d 49 d 27/31

7 day 28 d 49 d 13/31

14 day 28 d 49 d 3/31

21 day 28 d 49 d 3/31

None 28 d 49 d 3/35

None ---- 49 d 33/33

Chicken Anemia Virus (CAV)

Loss of immature T-cells in thymus

Decreased erythropoiesis and increased

fat infiltration of bone marrow

Effects of CAV on Immune

Response

CAV infectious resulting from transovarian or

infection shortly after hatch can be

immunosuppressive

Responses to IBV, NDV, and ILT are affected

Increased susceptibility to bacterial infections

(gangrenous dermatitis)

Age associated resistance to CAV induced

immunosuppression in birds older than 2 weeks

Effects of IBDV on Susceptibility of

Chickens to CAV

IBDV alters age-associated susceptibility

to CAV and allows CAV to be

immunosuppressive in older birds

Decreased dose of CAV is necessary to

cause disease

Marek’s Disease Virus

Interactions with other infectious agents

CAV

Subgroup J virus (Myeloid Leukosis)

E. coli

Coccidiosis

Avian Reoviruses

IBD (Gumboro)

Respiratory disease viruses

Avian Reoviruses

Specific Reoviruses—Miss-B Reovirus

Isolated from bursa of SPF sentinels

Antigenically similar to S1133 Reovirus

High mortality and reduced body weights in

broilers infected at 1 day of age

Bursa and thymic atrophy

Liver necrosis, tenosynovitis

Virus widely disseminated in tissues for

several weeks post infection

Avian Reovirus

Avian Reovirus (Miss-B isolate) can suppress

immune responses to NDV and IBV

Susceptibility to CAV is increased by prior

Reovirus exposure

CAV, IBDV, and Reovirus interact to induce

more severe disease

Programs to Minimize Impact of

Immunosuppressive Diseases

Accurate diagnosis

Control pathogens that are known immunosuppressive agents IBDV

CAV

Marek’s Disease virus

Interactions

Manage environmental factors than can exacerbate immunosuppressive diseases

Consider and control influence of breed and nutrition on disease susceptibility

Programs to Minimize the Impact of

Immunosuppressive Diseases

The impact of Subgroup J viruses and specific

Reoviruses are less definitive but appear to

play a significant role in some flocks

Interactions of pathogens often result in

increased susceptibility