In the case of piglets, the key consequence of PRRSV infection is a respiratory disease which main associated lesion is interstitial pneumonia.
The final outcome of the infection is determined mostly by the participation of other complicating agents, particularly bacteria although interactions with other viruses (e.g. Porcine Circovirus 2) have been demonstrated.
Differences among isolates with regard to the severity of the respiratory disease exist.
Gross lesions observed following PRRSV infection vary widely and may be dependent on the virus isolate, genetics of the infected pig, and stress factors (environment and health status of the pig herd). Lung lesions vary from none to diffuse consolidation and are commonly complicated by lesions resulting from concurrent bacterial infections which can localize separate or intermixed.
The economic impact of PRRS is substantial and global. The disease’s economic impact occurs through pig death losses, poor reproductive performance, poor growth rates and increased use of medications. Studies in the United States have estimated economic losses due to PRRS at $664 million per year — $1.8 million per day
. Studies estimate that the costs due to PRRS may range from $27 to $156 per litter, and approximately $4.32 per marketed pig.
Cost of PRRS in growing pigs:
- Significant decrease in average daily gain (ADG)
- Significant increase in death loss
- Represents a loss of $4.32/pig (performance loss & medication cost)