Porcine Reproductive and Respiratory Syndrome (PRRS) is a viral disease infecting sows and pigs which can lead to reproductive failure in breeding age herds and can cause pneumonia and increased mortality in young animals. It is the most economically significant disease to affect U.S. swine production since the eradication of classical swine fever.

To attempt to control and prevent PRRS, we must fully understand the disease and how biosecurity and management both play a role in reducing the economic impact of the virus.

The virus is one of the most important swine diseases of the past 50 years. In the U.S. alone, the total cost to the industry has been estimated at $664 million per year.

PRRS virus

The PRRS virus is a small, enveloped RNA virus classified in the virus family, Arteriviridae. Early studies identified two different genotypes of the virus. However, one of the aspects that makes PRRS so hard to prevent and control is its high mutation rate, making it difficult to effectively treat.

PRRS can affect all pigs no matter the age. Sows and gilts, and even some boars, can experience reproductive impairment or failure. Young, growing pigs are more likely to have the respiratory syndrome, but it can also occur in naïve finishing pigs and breeding stock.

Persistence is the single most significant epidemiological feature of the PRRS virus. The PRRS virus produces a chronic, ‘persistent-like’ infection in carrier pigs that can last longer than 200 days. According to Iowa State University’s College of Veterinary Medicine, some field observations suggest that most infected pigs eventually become immune and eventually clear the infection, ceasing to shed virus by 60 days post-infection.


Carrier pigs represent a constant threat of transmission to susceptible herd mates. Most commonly, the PRRS virus is transmitted from close contact between infected pigs and the rest of the herd. The PRRS virus has been found in many different porcine secretions and excretions including blood, semen, saliva, feces, aerosols, milk, and colostrum. Pigs can maintain infection for prolonged periods of time making the virus highly contagious.

In addition to transmission from close contact between animals, herd-to-herd transmission can occur. Replacement seedstock and boar semen can be direct routes of infection. The virus can also be transmitted via indirect routes such as coveralls and boots, contaminated transport vehicles, insects, and waterlines.

Control & Biosecurity

Controlling PRRS is more than simply vaccinating against the virus and sourcing seedstock inputs from PRRS negative herds. Virus variation, geographically dense swine populations, and unresolved transmission issues prevent there from being a single successful strategy to prevent, control or treat PRRS. Biosecurity is an extremely important management tool to prevent infection, maximize immunity, and minimize exposure as much as possible.

Before repopulating stock, it is essential to clean and disinfect your facilities. Biofilm provides a protective home that helps pathogens resist disinfection. The PRRS virus can live within biofilm and you cannot thoroughly disinfect your facility without completely removing biofilms found on surfaces and in waterlines.

Sterilex’s patented PerQuat technology was the first chemistry to receive EPA-registered anti-biofilm claims for industrial and public health use sites. Dissolving the biofilm structure and fully removing it from a surface is a proactive approach in preventing the repopulation of biofilm and microbial contamination.  FortiSolve provides efficacy against biofilm, and kills and inactivates organisms such as PRRS and other swine pathogens.

While control programs should be tailored to fit each farm’s situation, useful techniques to control secondary infections include early weaning and isolation of piglets, various PRRS vaccination protocols, regular serologic monitoring, and improving biosecurity practices.


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