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With increased incidence of porcine circovirus associated disease (PCVAD), many producers are taking a hard look at their entire disease management program in order to reduce exposure, severity and mortality from the disease.

One management approach is the use of vaccine to immunize pigs early, before exposure and the potential onset of disease symptoms. Recently, Boehringer Ingelheim Vetmedica, Inc., introduced Ingelvac® CircoFLEX™ in North America. Labeled for pigs 3 weeks of age or older, the 1 mL, single-dose vaccine has a duration of immunity of at least 4 months, protecting pigs from an early age beyond the critical period in grow finish.

Ingelvac CircoFLEX can be administered at weaning, without interference from maternal antibodies, priming the pig’s immune system against circovirus type 2 infection in early nursery.

Nursery pigs 5 to 10 weeks of age and finishers, two to three weeks after placement, have suffered clinical signs and lesions from PCVAD. The disease is characterized by respiratory, digestive, hemolymphatic, vascular and renal lesions associated with porcine circovirus type 2 (PCV2) infection. Affected pigs will present all or some of the following: cough, diarrhea, anemia, icterus, poor body condition, generalized lymphadenopathy and skin lesions. But the most significant clinical sign of infection is death.

Herds in eastern Canada were among the first in North America to experience explosive outbreaks of PCVAD, particularly in Quebec and Ontario starting in the fall of 2004.

It was in Quebec where a research team led by Boehringer Ingelheim Canada veterinarian Dr. Robert Desrosiers chose a large herd to field-test efficacy of the vaccine.

That 2006 trial involved nearly 3,800 pigs ranging from 19 to 59 days of age.1 The herd was PRRS and Mycoplasma hyopneumoniaenegative, but had consistently experienced PCVAD in the finishing phase, usually three to four weeks after placement. Sow performance was excellent, averaging 27 pigs per year, and nursery mortality was about 1 percent.

At the start of the study, every nursery pig received an injection on the same day – either a 1 mL placebo or 1 mL of Ingelvac CircoFLEX vaccine. All pigs were vaccinated. The crew was hired so that “farm staff would not know which pigs were vaccinated with Ingelvac CircoFLEX.” Pigs normally left the nursery at an average of 62 days of age, so those injected at 59 days were introduced into the first finishing unit only three days after treatment.

History repeated itself in the trial as placebovaccinated pigs began to show clinical signs of PCVAD about three to four weeks after entering all four finishing units (80 to 90 days of age). Clinical signs included wasting, lack of response to treatment, paleness, diarrhea and death. Some showed skin lesions suggesting porcine dermatitis and nephropathy syndrome.

Gross lesions included enlarged lymph nodes, particularly mesenteric; lungs that failed to collapse normally and that had interlobular edema; kidneys that were enlarged or with multiple white spots; lesions of enteritis suggestive of ileitis or salmonellosis; and edema of the mesentery. A few pigs also had enlarged spleens with thickened, hardened and dark red to black areas. Histological and immunohistochemistry results showed about 90 percent of pigs had lesions and antigenic loads compatible with a PCVAD diagnosis, confirming that this was the main condition.

It quickly became obvious which pigs received the Ingelvac CircoFLEX vaccine. Groups designated as the A pigs had a significantly higher mortality rate (dead and euthanized) than pigs in the B, or vaccinated, group (see chart).

Death loss, in fact, was reduced by 75 percent across all vaccinated age groups and by 95 percent among the youngest vaccinated group.

Dr. Desrosiers and his coworkers concluded that vaccine efficacy was excellent, whether pigs were vaccinated as young as 19 to 22 days or as old as 45 to 59 days of age.

Immunity also was quick to develop since pigs vaccinated only about four weeks before clinical signs appeared seemed to be protected.

Field studies are continuing in the U.S. to determine optimal timing of the vaccine.