| Porcine Reproductive and Respiratory Syndrome (PRRS) is a globally significant viral disease of swine. The link between outbreaks in separate farms within an area remains unclear despite biosecurity measures. We have investigated the vector potential of stable flies in the transmission of PRRSV under laboratory conditions. We first determined that blood seeking stable flies are attracted to pigs by olfactory cues. We determined stable flies could acquire the virus through a bloodmeal, and the amount of virus in the flies declined with time, indicating the virus does not replicate in fly digestive tissues. Transmission of the virus to naive pigs failed in all attempts. The volume of blood contained in the closed mouthparts of the stable fly appears to be insufficient to deliver an infective dose of the virus. We further examined the fate of PRRS virus in the hemolymph of the flies following a midgut barrier bypass. Virus levels were up to 9,500 times greater in the hemolymph when compared to those detected in the digestive tract at the same time point. Further study to test the saliva of inoculated stable flies for presence of the virus is needed to determine if PRRS virus can enter and escape stable fly salivary glands. Although stable flies are unlikely vectors of PRRS virus between animals, they may play a role in virus dissemination by harboring the virus and contaminating the environment. |
