Diseases associated with this family include: PCV-2: postweaning multisystemic wasting syndrome; CAV: chicken infectious anemia.

[3][4] Viruses in the family Circoviridae are non-enveloped, with icosahedral and round geometries, and T=1 symmetry.

[3] There are two main open reading frames arranged in opposite directions that encode the replication and capsid proteins.

[2][3] A stem loop structure with a conserved nonanucleotide motif is located at the 5' intergenic region of circovirus genomes and is thought to initiate rolling-cycle replication.

A cyclovirus—cyclovirus-Vietnam—has been isolated from the cerebrospinal fluid of 25 Vietnamese patients with CNS infections of unknown aetiology.