Introduction

Chicken anaemia virus, or CAV, is a member of the circoviridae

Circoviridae

The Circoviridae are a family of viruses. These are small, relatively poorly-studied viruses, with circular, single-stranded DNA genomes of approximately one to four kilobases-Virology:...

 family. It is a non-enveloped icosahedral single stranded DNA virus.

Infection causes anaemia, bone marrow atrophy

Atrophy

Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...

, and severe immunosuppression

Immunosuppression

Immunosuppression involves an act that reduces the activation or efficacy of the immune system. Some portions of the immune system itself have immuno-suppressive effects on other parts of the immune system, and immunosuppression may occur as an adverse reaction to treatment of other...

 in poultry

Poultry

Poultry are domesticated birds kept by humans for the purpose of producing eggs, meat, and/or feathers. These most typically are members of the superorder Galloanserae , especially the order Galliformes and the family Anatidae , commonly known as "waterfowl"...

 as the virus affects the production of red blood cells (RBC), white blood cells (WBC) and platelets. Clinical signs of CAV infection are predominantly found in young chicks due to vertical transmission

Vertical transmission

Vertical transmission, also known as mother-to-child transmission, is the transmission of an infection or other disease from mother to child immediately before and after birth during the perinatal period. A pathogen's transmissibility refers to its capacity for vertical transmission...

 from the breeder hens whose maternal antibodies

Passive immunity

Passive immunity is the transfer of active humoral immunity in the form of readymade antibodies, from one individual to another. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta, and can also be induced artificially, when high levels...

 have not yet formed following exposure. Clinical disease is rare today because of the widespread practice of vaccinating breeders, but the subclinical form of the disease - which normally affects birds more than two weeks of age following horizontal transmission

Horizontal transmission

Horizontal transmission is the transmission of a bacterial, fungal, or viral infection between members of the same species that are not in a parent-child relationship....

 of the virus via the oro-faecal route

Fecal-oral route

The fecal-oral route, or alternatively, the oral-fecal route or orofecal route is a route of transmission of diseases, in which they are passed when pathogens in fecal particles from one host are introduced into the oral cavity of another potential host.There are usually intermediate steps,...

 - is ubiquitous. Additionally, the virus is very resistant in the environment, making elimination very difficult. It is not a zoonosis

Zoonosis

A zoonosis or zoonoseis any infectious disease that can be transmitted from non-human animals to humans or from humans to non-human animals . In a study of 1415 pathogens known to affect humans, 61% were zoonotic...

.
The vaccine has the ATCvet code

The disease/virus has many names including chicken anaemia, blue wing disease, anemia dermatitis syndrome, chicken/avian infectious anaemia, hemorrhagic aplastic anaemia syndrome, infectious chicken anaemia, chicken infectious anaemia virus and chicken anaemia agent.

Clinical Signs & Diagnosis

Clinical signs include a pale comb, wattle, eyelids, legs and carcass, anorexia

Anorexia (symptom)

Anorexia is the decreased sensation of appetite...

, weakness, stunting, unthriftiness, weight loss, cyanosis

Cyanosis

Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...

, petechia

Petechia

A petechia is a small red or purple spot on the body, caused by a minor hemorrhage ."Petechiae" refers to one of the three major classes of purpuric skin conditions. Purpuric eruptions are classified by size into three broad categories...

tion and ecchymoses, lethargy and sudden death. Neurological signs include dullness, depression and paresis

Paresis

Paresis is a condition typified by partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it also can be used to describe the muscles of the eyes , the stomach , and also the vocal cords...

. Subclinical infection my cause reduced growth rates and other health problems.

A presumptive diagnosis can be made based on the clinical signs and a low haematocrit reading (<27%). Virus isolation, increased antibody titres

Antibody titer

An antibody titer is a measurement of how much antibody an organism has produced that recognizes a particular epitope, expressed as the greatest dilution that still gives a positive result. ELISA is a common means of determining antibody titers....

, immunoperoxidase

Immunoperoxidase

Immunoperoxidase is a type of immunostain used in molecular biology, medical research, and clinical diagnostics. In particular, immunoperoxidase reactions refer to a sub-class of immunohistochemical or immunocytochemical procedures in which the antibodies are visualized via a peroxidase-catalyzed...

 staining, ELISA

ELISA

Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...

, PCR or indirect Immunofluorescence

Immunofluorescence

Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on biological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows...

 can be used to confirm the presence of the virus.
Post mortem

Autopsy

An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...

 finding should show significant atrophy

Atrophy

Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations , poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, disuse or lack of exercise or disease intrinsic to the tissue itself...

 of the lymphoid organs, haemorrhage throughout the tissues and pale watery bone marrow.

Treatment & Control

There is no specific treatment for infected birds. Culling

Culling

Culling is the process of removing animals from a group based on specific criteria. This is done either to reinforce certain desirable characteristics or to remove certain undesirable characteristics from the group...

 of infected birds is normally performed in infected commercial flocks. Birds that have been infected develop immunity

Immunity (medical)

Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...

 to the virus.

Vertical spread of the disease can be controlled by the vaccination

Vaccination

Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...

of breeding hens with both live attenuated and wild vaccines. These vaccines reduce the vertical transmission rate. Appropriate hygiene and biosecurity measures should be employed to control the disease.