The Co-Infection Conundrum: How Bad Can Bad Get?

Sep 08, 2025

For years, the swine industry has talked at length about multiple pathogens and multiple infectious agents. JD Fiechtner, senior key account veterinarian for Boehringer Ingelheim, says only recently has the industry begun to fully realize the impacts of two infections affecting the pig at the same time.

“For a long time, we thought of them separately, as just a one plus one – an additive component,” Fiechtner explains. “What the industry is realizing now is that we are seeing worse outcomes from these infections when they’re together than when we just considered them independent of each other.”

Two recent studies back up the compounding impact pigs face when hit with more than one pathogen at a time. Scientists looked at the impact of co-infections of porcine reproductive and respiratory syndrome (PRRS) plus Lawsonia intracellularis and PRRS plus porcine circovirus type 2d (PCV2d).

“Most everybody is dealing with PRRS infections, and there is not any one answer to manage that disease,” Fiechtner says. “It’s very common, and it’s very common to be frustrated with it.”

A Dynamic Discovery
In the first study, scientists evaluated the highly virulent PRRS 1-7-4 strain in combination with PCV2d. The study revealed that giving a PCV2d vaccine as prevention or protection results in better economic outcomes in co-infected PRRS pigs. Not only did they see a decrease in mortality, but they also saw a decrease in the number of pigs treated for health challenge signs that would require an antibiotic or other supportive therapy.

“We call this dynamic pig health, because it is a dynamic system within the pig,” he says. “It’s not just one issue. You have to consider all the aspects of disease. That’s why looking at the overall pig and the overall challenges when making your intervention strategies is very important.”

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