MERCK ANIMAL HEALTH
TECHNICAL SERVICES BULLETIN
Significance & Diagnosis of Porcine Circovirus
Type 2 (PCV2) as a Reproductive Pathogen of Swine
Key Points:
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Porcine circovirus type 2 (PCV2) is a pathogen of swine that has been associated with several disease processes including
reproductive failure (1, 2, 3).
As a reproductive pathogen of swine, PCV2 has the ability to cause mummified piglets, stillborn piglets, low viability piglets and
elevated pre-weaning mortality (2, 3, 4).
PCV2 infection is characterized by months of viremia in infected pigs and is capable of being vertically transmitted (from dam to
offspring) in utero as well as in colostrum and milk. It is important for sows and gilts in breeding herds, as well as replacement
gilts, to be free of PCV2 viremia during gestation and lactation.
When Circumvent® PCV or Circumvent PCV M (Merck Animal Health) are given to replacement gilts at five and eight weeks of
age with a booster prior to breeding, no tested piglets from 82 litters were found to be viremic with PCV2 (9). These results are in
stark contrast to the PCV2 survey work by Shen et al (5).
Vertical transmission is a potentially important means of PCV2 transmission in swine breeding herds.
Prevalence of Vertical Transmission of PCV2
One survey of the prevalence of PCV2 viremia in dams and newborn piglets in clinically normal breeding herds demonstrated that 6
percent of dams and 43 percent of piglets in five different herds were positive for the presence of PCV2 by polymerase chain reaction
(PCR) testing (5).
PCV2 Control in Swine Breeding Herds
To prevent potential reproductive failures and vertical transmission of PCV2 to offspring, it is important to effectively immunize the
breeding herd and replacement gilts against PCV2 infection and/or viremia.
It has been demonstrated that intentional exposure of pigs to live PCV2 by serum injection does not prevent disease or viremia (6).
There is a quantitative (amount) and qualitative (quality) difference in the immunity resulting from Circumvent PCV or Circumvent PCV
M use compared to other PCV2 vaccines (7).
It has also been demonstrated that vaccination of gilts with CircoFLEX® (Boehringer Ingelheim Vetmedica, Inc) with subsequent
PCV2 challenge does not prevent viremia in gilts, nor does it prevent vertical transmission of PCV2 to offspring (8).
Vaccination of breeding herd members and replacement gilts with Circumvent PCV has been demonstrated to be an effective tool for
the control of PCV2-associated disease and reduction of vertical transmission of PCV2 in breeding herd members and offspring (9).
PCV2 Diagnostic Series #1: Diagnostic Evaluation of PCV2 Status of Replacement Gilts
Purpose of Testing:
This diagnostic evaluation assesses the PCV2 status of a group of replacement gilts.
Target Animals:
Newly or recently delivered gilts to isolation/acclimation barns that have a vaccination history of:
1. Partial dose Circumvent PCV or Circumvent PCV M vaccination
2. CircoFLEX vaccination
3. No vaccination against PCV2, although this is rare
Number of Gilts to Test:
30 individual blood samples
Test to Request (Each test costs $25-$30):
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PCR for PCV2 on 1:5 composite, pooled samples
Six PCV2 PCR tests will be run from 30 individual gilt blood
samples
Laboratory to Use:
Any diagnostic lab that does a significant volume of swine diagnostic
work will be able to perform a PCV2 PCR.
Possible Outcomes:
1. If all collected samples are NEGATIVE:
■■ No further testing or action required
■■ Monitor additional replacement gilt groups periodically, or if
source changes
■■ Evaluate newborn piglet’s PCV2 status
2. If some or all collected samples are POSITIVE:
■■ The potential for vertical transmission of PCV2 exists
■■ Evaluate PCV2 vaccination protocol of gilts in multiplication
system and in isolation/acclimation phase. Implement a
Circumvent PCV or Circumvent PCV M vaccination program
■■ Evaluate PCV2 status of newborn piglets
■■ Vaccinate future replacement gilts with Circumvent PCV or
Circumvent PCV M, according to label directions and booster prior
to breeding
PCV2 Diagnostic Series #2:
Diagnostic Evaluation of the PCV2 Status of
Mummified, Stillborn, or Weak-born Piglets
Purpose of Testing:
This diagnostic evaluation assesses the PCV2 status of mummified,
gestational stillborn or weak-born piglets.
Target Animals:
Laboratory to Use:
Any diagnostic lab that does a significant volume of swine diagnostic
work will be able to perform a PCV2 PCR.
Possible Outcomes:
1. If all collected samples are NEGATIVE:
■■ No further testing or action required
■■ Monitor suspect piglets, mummies, or stillborns as clinical signs or
production records dictate
2. If some or all collected samples are POSITIVE:
■■ Vertical transmission of PCV2 exists
■■ Discuss vaccination of the breeding herd with Circumvent PCV or Circumvent PCV M with a veterinarian
■■ Evaluate PCV2 vaccination protocol of gilts in multiplication
system and in isolation/acclimation phase. Implement a
Circumvent PCV or Circumvent PCV M vaccination program
■■ Vaccinate future replacement gilts with Circumvent PCV or
Circumvent PCV M, according to label directions and booster prior
to breeding
■■ Discuss the impact of weaning PCV2 viremic piglets on the farm’s
PCV2 vaccination program with a veterinarian
If you have any questions, contact Merck Animal Health Swine
Business Unit Sales Representative or Technical Services.
References
Opriessnig, T. et al. (2007) Journal of Veterinary Diagnostic
Investigation 19: 591-615.
Woods, A. et al. (2009) Journal of Swine Health and Production
17(4): 210-216.
Pittman, J. (2008) Journal of Swine Health and Production 16:
144-148.
Brunborg, I. et al. (2007) Journal of Veterinary Diagnostic
Investigation 19: 368-375.
Gilt (parity 1) farrowed mummies, gestational stillborn fetuses and/or
unsuckled or low viability piglets.
Shen, H. et al. (2010) Preventive Veterinary Medicine 97(3-4):
228-236.
Tissue of Choice for Diagnostic Testing:
Thomas, P. et al. (2007) Journal of Swine Health and Production
15(6): 330-338.
Number to Test:
Almond, G. et al. (2010) International Pig Veterinary Society 0.070 p.
108.
Myocardium or unsuckled piglet sera
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Collect no more than two samples of myocardium or serum per
clinically affected litter
Collect appropriate samples from up to 15 litters
Test to Request (Each test costs $25-$30):
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Madson, D. et al. (2009) Theriogenology 72(6): 747-754.
Hobson, B. et al. (2011) American Association of Swine
Veterinarians Poster Session: Veterinary Students.
Serum: PCR for PCV2 on 1:4 composite samples
Myocardium: immunohistochemistry (IHC) for PCV2
Merck Animal Health
Summit, New Jersey 07901
www.merck-animal-health-usa.com Technical Service: 1-800-211-3573 Customer Service: 1-800-356-7470
Copyright © 2013 Intervet Inc., a subsidiary of Merck & Co., Inc. All rights reserved. SW-PCV-TB-006-2 (04-12)