Chicken Infectious Anemia (CIAV): Gyrovirus Pathology & Immunity
Veterinary reference covering Anelloviridae vertical transmission, thymic atrophy, bone marrow aplasia, and secondary bacterial coinfections.
Scientific Overview
Chicken Infectious Anemia Virus (CIAV) is an immunosuppressive viral pathogen of young chickens caused by a small non-enveloped Gyrovirus. CIAV destroys erythroblast precursor cells in bone marrow and T-lymphocytes in the thymus, producing severe aplastic anemia, subcutaneous hemorrhages, blue wing disease, and secondary bacterial mortality.
Etiology & Target Precursor Cells
Chicken Infectious Anemia Virus (CIAV) is defined as a circular single-stranded DNA virus belonging to the family Anelloviridae, genus Gyrovirus (encoding VP1, VP2, and apoptotic VP3/Apoptin proteins).
Primary vertical transmission occurs when non-immune breeder pullets become infected during early lay, passing virus to eggs. Chicks infected in their first 2 weeks lack maternal antibodies and develop acute clinical anemia (Balamurugan & Kataria, 2006).
Necropsy Pathology & Hematology
Clinical pathology signs in 2 to 4-week-old chicks:
- Aplastic Anemia: Packed cell volume (PCV / Hematocrit) drops below 20% (normal 30–35%). Blood appears watery and pale.
- Thymic Atrophy: Severe atrophy of the thymic lobes and Bursa of Fabricius due to Apoptin-induced lymphocyte destruction.
- Pale Bone Marrow: Femur bone marrow turns yellow or fatty-pink instead of normal dark red. Subcutaneous hemorrhages ('Blue Wing Disease') are common.
Breeder Immunization & Control
Control relies on vaccinating breeder pullets with live CIAV vaccines prior to egg production (between 13 and 15 weeks of age) to ensure uniform maternal antibody transfer to day-old offspring.
All scientific data, diagnostic criteria, and performance benchmarks presented on this page are derived from published peer-reviewed journals and official veterinary codes:
- Avian Pathology & Diagnostics: World Organisation for Animal Health (WOAH, 2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Paris, France.
- Poultry Diseases & Histology: Swayne, D.E., et al. (2020). Diseases of Poultry (14th ed.). Wiley-Blackwell / American Association of Avian Pathologists.
- Nutrition & Feed Chemistry: Leeson, S. & Summers, J.D. (2001). Commercial Poultry Nutrition (3rd ed.). University Books, Guelph, Ontario.
- Commercial Breed Standards: Aviagen (2024). Ross 308 & Cobb 500 Broiler Performance Objectives. / Lohmann Breeders (2024). Lohmann Brown Management Guide.