This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.
How does PRRS incidence vary based on farm status? This is the question answered in this week’s edition of the Science Page. Three different formulas were used to calculate the incidence in each of the group over type. First, the initial number of farms of each status at the beginning of the year was used as the denominator. Then, the denominator was changed to the total number of farms that entered each status since the beginning of the year. Lastly, weekly incidences calculated for each of the group since the beginning of the year were added. Calculations went back for the last 3 years.
Key points from this week edition:
- Cumulative incidence is higher in those farms that are under status 2, 2vx and 2fvi.
- The incidence is lower in farms that had recently an outbreak or those that are completely negative.
- Different ways of calculating incidence by herd status lead to the same overall conclusion.