AASV Board Approves Porcine Circovirus Position Statement

At its fall meeting, the AASV Board of Directors approved a proposed name change and case definition involving Porcine Circovirus type 2 (PCV2).

The Porcine Circovirus ad hoc committee, formed by the AASV Board at its annual meeting in Kansas City, proposed that the association adopt the name Porcine Circovirus Associated Disease (PCVAD) for the variety of clinical presentations currently described coincident with PCV2 infections. This was an attempt by the committee to recognize the variability in clinical signs currently associated with exposure to this virus in pigs. The Board approved the motion.

In addition, the committee also proposed a formalized case definition to describe the minimum findings necessary to associate a given clinical presentation with exposure to PCV2. To derive this case definition, the committee elected to follow the methodology utilized by the Centers for Disease Control and Prevention (CDC) when describing the emergence of a previously unrecognized disease. The recommendation was also approved by the Board. The case definition is presented below.

Porcine Circovirus Associated Disease (PCVAD) Case Definition

This case definition is considered to be a dynamic document which will be altered as additional information becomes available. The CDC model of describing the clinical expression of a new disease when a definitive diagnosis is not known was used in developing the format for the following case definition involving PCVAD.

PCVAD can be subclinical or include one or more of the following clinical manifestations concurrently:

  1. Multisystemic disease with weight loss (formerly known as PMWS)
  2. High mortality: Doubling of historical mortality rate without introduction of a new known pathogen.
  3. Respiratory signs including pneumonia
  4. Porcine Dermatitis and Nephropathy Syndrome (PDNS)
  5. Enteric signs including diarrhea and weight loss
  6. Reproductive disorders including abortions, stillbirths and fetal mummification (diagnosis requires the presence of fetal myocarditis associated with PCV2 antigen in lesions)

PCVAD is a broad categorization of multisystemic diseases that are confirmed by documentation of the following histopathological findings in affected pigs:

  1. Depletion of lymphoid cells in lymphoid tissues of the growing pigs.
  2. Disseminated granulomatous inflammation in one or more tissues (e.g. spleen, thymus, intestines, lymph nodes (sternal, bronchial, inguinal and mesenteric), lung, kidney, liver, tonsil, etc.).
  3. Detection of PCV2 within the lesions of growing pigs.
  4. PCV2 associated reproductive disease diagnosis requires the presence of PCV2 antigen in fetal myocarditis lesions.