Control of Coinfections
Chlortetracycline (CTC)-treatment used in the M. hyopneumoniae-PCV2-coinfection model provided evidence that the CTC treatment is highly efficacious in reducing lesions associated with PCV2 and M. hyopneumoniae coinfection (Halbur et al., 2005). At 6 weeks of age, pigs were inoculated intratracheally with M. hyopneumoniae, followed by intranasal inoculation with PCV2 at 8 weeks of age. At 8 weeks of age, half of the pigs received a CTC feed additive at an approximate dose of 22 mg/kg. The CTC-treated and coinfected pigs had significantly less severe clinical disease, macroscopic and microscopic lung lesions compared to the non-treated coinfected pigs.
A recent study evaluated the losses or gains associated with the use of three different commercially-available M. hyopneumoniae bacterins in pigs experimentally co-infected with M. hyopneumoniae and PCV2. Two hundred ninety-six M. hyopneumoniae-negative pigs were randomly assigned to one of four treatment groups. Three commercial vaccines, administered as per label direction, were tested: two bacterins containing an oil-based adjuvant and one bacterin containing an aqueous-based adjuvant. The M. hyopneumoniae challenge resulted in severe macroscopic and microscopic lesions in the non-vaccinated pigs. Pigs in all vaccine treatment groups had significantly higher mean body weight and average daily gain on 100 and 131 DPI, compared to the unvaccinated controls (Halbur et al., 2005).
Timing of use of adjuvanted bacterins may also be important in herds with recurrent PCVAD. Pigs should be vaccinated two to four weeks prior to expected PCV2 exposure as opposed to at or shortly after exposure, performed best (Opriessnig et al., 2006).
Rodibaugh (2002) described changing a lepto-parvo-erysipleas program from weaning to pre-farrowing in a herd with approximately 7-8% mortality due to PCVAD. After intervention, the mortality rate declined to 2-3% (Rodibaugh, 2002).
Conventional pigs were experimentally coinfected with PCV2 and PPV and the effect of PPV vaccination in reducing disease and lesions associated with PCV2/PPV coinfection was investigated (Opriessnig et al., 2004). PPV vaccination was done 24 and 10 days before PCV2/PPV virus challenge with a killed PPV vaccine. Clinical signs consistent with PMWS (fever, respiratory disease, jaundice, weight loss) were seen in vaccinated and non-vaccinated PCV2/PPV coinfected pigs (Opriessnig et al., 2004).
Halbur PG, Opriessnig T, Thomas P: Best practices for control of PCV2-associated diseases. In: Proc Swine Disease Conf Swine Pract, Ames, Iowa. 13:98-107, 2005
Opriessnig T, Fenaux M, Yu S, Evans RB, Cavanaugh D, Gallup JM, Pallares FJ, Thacker EL, Lager KM, Meng XJ, Halbur PG: Effect of porcine parvovirus vaccination on the development of PMWS in segregated early weaned pigs coinfected with type 2 porcine circovirus and porcine parvovirus. Vet Microbiol. 98:209-220, 2004
Opriessnig T, Halbur PG, Yu S, Thacker EL, Fenaux M, Meng XJ: Effects of the timing of the administration of Mycoplasma hyopneumoniae bacterin on the development of lesions associated with porcine circovirus type 2. Vet Rec. 158:149-154, 2006
Rodibaugh M: Defining today’s disease complexes. Nat Hog Farm. 12:32, 2002