Science page: Investigating PRRS summer outbreaks in the US

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.

This week we are sharing an investigation into PRRS summer outbreaks by Dr. Juan Sanhueza and the MSHMP team.

Key Points

  • Each year approximately 3% of the sow farms have a PRRS outbreak during the summer.
  • The incidence of summer PRRS breaks has been constant over the last 9 years.
  • There are geographical areas with higher or lower risk of summer breaks.
prevalence of summer PRRS outbreaks per year
Figure 1. PRRS summer outbreak incidence per year between 2009 and 2017.

A summer outbreak was defined as a PRRS case that happened between June 21st and September 21st of the year. The mean incidence of PRRS summer outbreaks was 3.2% between 2009 and 2017, ranging between 1.6% and 4.4%. The trend was stable among the years. (Figure 1) Not all areas are equal against summer outbreaks. Indeed, the region of Southern Minnesota – Northern Iowa is more at risk of outbreaks than others like Southern Iowa or Eastern North Carolina. (Figure 2)

areas with higer lower PRRS risk in the summer
Figure 2. Geographical areas with higher (red) and lower (blue) PRRSV incidence risk

Biosecurity measures against PRRSV should therefore be a concern all year round for swine producers!

 

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