Identity

An acute, immunosuppressive viral disease of young chickens caused by the Chicken Anemia Virus (CAV). It targets hemocytoblasts in the bone marrow and T-lymphocytes in the thymus, causing aplastic anemia, generalized lymphoid atrophy, and severe immunosuppression.

Overview

Chicken Infectious Anemia (CIA) is a high-priority immunosuppressive virus characterized by its small, single-stranded DNA genome. The virus selectively induces apoptosis (via the VP3 apoptin protein) in bone marrow hemocytoblasts and cortical thymic T-lymphocytes. This results in severe anemia and a critically compromised cell-mediated immune system. Young chicks (<3 weeks) show clinical disease, while older birds suffer subclinical immunosuppression. Prevention relies entirely on ensuring breeder flocks are actively vaccinated (live CAV vaccines) prior to lay to ensure the vertical transfer of protective maternal antibodies to progeny, preventing devastating secondary infections.

Structured Facts

Classification

Viral > Infectious Pathogen

Epidemiology

• Severity: High (due to immunosuppression/vaccine failure)
• Affected Species: Poultry
• Affected Age: Young chicks < 3 weeks of age (clinical); older birds (subclinical)
• Transmission: Vertical (transovarian shedding for 3-6 weeks if breeder infected during lay); Horizontal (fecal-oral)
• Mortality: 10% to 20% (uncomplicated), >60% with secondary bacterial complications
• Morbidity: High in chicks from non-immune breeders
• Economic Importance: High (immunosuppression leads to secondary infections and vaccine failure)

Clinical Signs

• Early/Intermediate: Severe depression, progressive pallor of the comb, wattles, and skin, weight loss
• Advanced: Subcutaneous hemorrhages, localized necrotic dermatitis on wings ("blue wing disease"); targets Hematopoietic (bone marrow) and Immune systems (thymus)
• Postmortem Findings: Severe atrophy of the thymus and bursa of Fabricius; pale yellow, fatty bone marrow in the femur; subcutaneous/intramuscular hemorrhages in breast and thigh.

Diagnosis

• Field Diagnosis: Pale chicks with severe thymic atrophy and fatty bone marrow
• Laboratory Tests: PCR, ELISA (to monitor breeder flock titers), Histopathology (thymic cortical lymphocyte depletion)
• Differential Diagnosis: Infectious Bursal Disease, Aflatoxicosis, Sulfa drug toxicity

Treatment

• Medicines: None exist

Prevention

• Vaccination: Live CAV vaccines for commercial breeders (drinking water/injection) administered between 13 and 15 weeks of age (prior to lay)
• Biosecurity: Mitigated by standard Biosecurity Protocols
• Farm Management: Ensure maternal antibody transfer to progeny

Quantitative Data

• Morbidity Rate: High
• Mortality Rate: 10-20% (uncomplicated), >60% (complicated)
• Target Age: < 3 weeks

Relationships

• Vaccines: Live CAV vaccines (Breeders)
• Medicines: None
• Predisposing Relationships: Strongly synergistic with IBDV or Marek's Disease, leading to gangrenous dermatitis and secondary opportunistic infections.