Saturday, 5 March 2011

New porcine circovirus found in American pigs - APE

News of yet another circovirus in pigs, found in Kansas, is now reaching the media.

It is possible to trace a vague reference to APE being found in Northern Ireland in veterinary sources during 2010. That really matters. The only health testing station for British live export pigs was in Northern Ireland and closed down by constant circovirus outbreaks years ago.

The discovery of yet another killer circovirus underlines just how serious circovirus in pigs is – and the significance of the British cover-up of an epidemic in 1999 and since.

That initial outbreak of circovirus was recorded in veterinary circles, including by the OIE, but otherwise the situation in Britain did not reach the lay media. Later, a couple of years later, though, the past president of the OIE (United Nations) did complain about Britain’s behaviour over the outbreak. He maintained it should have been made internationally notifiable at Britain's request. Circovirus is still not notifiable.

Circovirus is not just a problem for pig farming. The repercussions spread far and wide, not least in the increasing antibiotic resistance in drugs used to restore us to health from illness and, indeed, even alive.

KSU report here

A new disease syndrome associated with porcine circovirus type 2 (PCV2)

Ada G. Cino-Ozuna1, Steven Henry2, Richard Hesse1, Jerome C. Nietfeld1, Jianfa Bai1, H. Morgan Scott1, Raymond R.R. Rowland1*

1. Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66506
2. Abilene Animal Hospital, Abilene KS 67410

Porcine circovirus-associated disease (PCVAD) encompasses a group of progressive wasting syndromes linked to porcine circovirus type 2 (PCV2). In late 2009, “well doer” nursery and younger finisher pigs from PCV2-vaccinated herds in the U.S. Midwest experienced peracute syndrome, called acute pulmonary edema (APE), with mortality reaching 20% in some affected groups. Clinical signs included the rapid onset of respiratory distress followed by death.

Often, pigs were found dead with no previous indication of disease signs. The clinical cases were submitted to the Kansas State Veterinary Diagnostic Laboratory (KSVDL) as part of a routine infectious disease investigation by a private veterinarian. Polymerase chain reaction (PCR) and immunohistochemistry (IHC) were used to assess PCV2 infection. All APE pigs were positive for PCV2 DNA in sera and tissues with some Ct values as low as seven. A common microscopic lesion was fibrinoid necrosis of the blood vessel wall with surrounding regions showing evidence of pulmonary edema. In most of the affected pigs, there was diffuse lymphoid depletion, and a few pigs possessed rhinitis.

In conclusion, this peculiar presentation of PCV2 infection in nursery and young finisher pigs is a likely consequence of the failure to pass maternally-derived antibodies (MDA) to the newborns, which is due to the declined levels of antibody in breeding damns vaccinated at 6 to 8 weeks of age, making newborns susceptible to PCV2 infection prior to vaccination.