Dr. Chamba Pardo and colleagues from the University of Minnesota share results of the implementation of sow vaccination to control influenza infections in pigs at weaning through a special issue article published in Transboundary and Emerging Diseases.
- Sow vaccination against IAV was effective at reducing the number of infected groups of pigs at weaning, and the number of positive nasal swab pools within a group.
- Both prefarrow or whole herd vaccination protocols, and use of commercial or autogenous inactivated vaccines, yielded significant and similar reduction of IAV infections in pigs at weaning.
- Sow vaccination can help control IAV infections in pigs at weaning and, thus, minimize transmission to growing pigs and other farms.
While producers and veterinarians spend a lot of resources trying to figure out the best influenza A virus (IAV) sow vaccination strategy for their herds, vaccination is then often implemented without any follow‐up measure of effectiveness on influenza infection parameters post‐vaccination. In this study, the effects of sow vaccination protocols and type of vaccines on IAV infections in pigs at weaning from a cohort of 52 breed‐to‐wean farms were prospectively assessed. The final aim was to provide information on the effectiveness of the various vaccination protocols implemented under field conditions.
Materials & Methods
A cohort of 52 breeding herds belonging to different pork‐producing companies at different locations in the United States were voluntarily enrolled according to their IAV history and sow vaccination protocol. Each enrolled farm submitted 30 nasal swabs collected from pigs prior to weaning on a monthly basis for 6 months, between January 2013 and November 2013 (prospective longitudinal study). On each herd, one pig was sampled in each litter by conveniently selecting 30 litters located in the farrowing room(s) housing the oldest piglets prior to wean in the farm. Nasal swabs were tested for IAV by reverse transcription (RT)‐PCR.
For more information regarding the experimental design, sample collection and testing, please refer back to the full manuscript on the journal’s webpage.
Results & Discussion
Of the 52 farms, 48% (n = 25) tested IAV positive for at least one monthly sampling event during the study. Overall, of 9,150 nasal swab pools (3 individual nasal swabs/pool), 15% (458/3050) of pools tested IAV positive. At the farm level, 44% (14/33) of the vaccinated farms and 58% (11/19) of the non‐vaccinated farms tested IAV positive at least once. Thus, there were no statistical differences in the number of positive farms between vaccinates and non‐vaccinates, and between farms with different vaccination protocols and vaccine types. At the group level, however, the proportion of IAV‐positive groups of pigs at weaning in vaccinated farms was lower (16%) than that in non‐vaccinated ones (40%). The odds of groups of pigs testing IAV positive at weaning were significantly lower in vaccinated farms compared to non‐vaccinated ones.
In summary, sow vaccination against IAV was effective at reducing the number of infected groups of pigs at weaning, and the number of positive pools within a group. Compared with no vaccination, both prefarrow or whole herd vaccination protocols, and use of commercial or autogenous inactivated vaccines, yielded significant and similar reduction of IAV infections in pigs at weaning.
To read the results and discussion in more detail, refer to the full manuscript here.
Although vaccination is the main measure to control influenza A virus (IAV) in swine, there is limited information on the efficacy of sow vaccination on reducing IAV infections in pigs at weaning. We assessed the effect of sow vaccination on IAV infection in pigs at weaning in a cohort of 52 breeding herds studied prospectively. Herds were voluntarily enrolled according to their IAV history, sow vaccination protocol and monitored during six months (prospective longitudinal study). On each herd, nasal swabs were collected monthly from 30 pigs at weaning and tested for IAV by RT-PCR. IAV was detected in 25% (75/305) of sampling events. Of 9,150 nasal swab pools (3 individual nasal swabs/pool), 15% (458/3050) of pools tested IAV positive. IAV infections in pigs at weaning were lower in vaccinated herds compared to non-vaccinated ones. Moreover, no significant differences were seen between prefarrow and whole herd protocols, or the use of commercial versus autogenous IAV vaccines. Prefarrow and whole herd vaccination protocols reduced the odds of groups testing IAV positive at weaning in comparison with no vaccination. Our results are relevant when considering implementation of sow vaccination to control influenza infections in pigs at weaning and, hence, minimize transmission to growing pigs and other farms.