A Systematic Review: Is Porcine Kobuvirus Causing Gastrointestinal Disease in Young Pigs?

SIMPLE SUMMARY: In 2008, researchers described a new virus, porcine kobuvirus (PKV). Some viruses are very harmful, while others infect animals without having any significance for their health. Some researchers have suspected that porcine kobuvirus causes gastrointestinal disease (e.g., diarrhea) in pigs. Therefore, this paper tried to answer the question: Is porcine kobuvirus a cause of gastrointestinal disease in young pigs? A systematic literature review was conducted, meaning that a database was searched for all reports of research studies investigating kobuvirus in pigs. In general, there was not much research of good quality that could possibly answer the question. Therefore, the study concluded that there is a lack of good evidence supporting the idea that PKV causes gastrointestinal disease. The absence of such documentation does not mean that we can conclude the opposite: that PKV is not causing gastrointestinal disease. That said, the sparse research available did indicate that PKV has a limited ability to cause diarrhea. ABSTRACT: Since porcine kobuvirus (PKV) was first described in 2008, researchers have speculated whether the virus is of clinical importance. This systematic literature review answers the question: Is porcine kobuvirus a cause of gastrointestinal disease in young pigs? A case-control study showed that PKV was not associated with neonatal diarrhea. A cohort study suffered from a very small sample size (n = 5), and in an experimental trial, the effect of PKV inoculation could not be separated from the effect of being inoculated with porcine epidemic diarrhea virus. In 13 poorly defined observational studies, more than 4000 young pigs had been assigned a diarrhea status and their feces analyzed for PKV. Unfortunately, the studies lacked well-characterized unbiased samples, and thus the strongest possible inference from these studies was that a very strong association between PKV and diarrhea is unlikely. PKV was commonly detected in non-diarrheic pigs, and this could indicate that PKV is not a sufficient cause in itself or that reinfection of individuals with some immunological protection due to previous infections is common. Conclusively, there is a lack of good evidence of PKV being a cause of gastrointestinal disease, but the sparse available evidence suggests that PKV is of limited clinical importance.