Porcine Circoviral Disease – From Inception to Successful Control
Porcine Circovirus Diseases (PCVD) were first described in the 1990’s in Canada as Postweaning Multisystemic Wasting Syndrome which affected grower and nursery pigs by respiratory disease, wasting, enlarged lymph nodes, pallor, enteritis and jaundice. It is caused by porcine circovirus type 2 (PCV2) which has multiple strains. In young pigs, passively acquired PCV2 antibody is protective for 6-8 weeks. Affected farms have higher fetal mummification rates, stilbirths, abortions, prenatal myocarditis and variable amounts of PCV2 antigen in fetal sera and tissues. To diagnose PCVD, the classical clinical signs, histopathological lesions and PCV2 antigen associated with lesions should be present. Diagnosis can be difficult due to multiple ongoing infections. The impact of PCVD and coinfections can be reduced by good production practices and also the use of PCV2 vaccines. These vaccines have high efficacy when given to piglets and reduces the viral load, viremia, lesions, mortality and improves growth rates. Often the vaccine is given around weaning at 3 weeks of age. If mortality levels remain high after implementing vaccinations, diagnostics should be used to identify coinfections.