21 Feb 2014

How Do Fish Catch a Virus? They Eat It

0 Comment

Viral hemorrhagic septicemia virus (VHSV) is just as unpleasant as it sounds for fish, leading to considerable losses of fish both in the wild and at some European fish farms. VHSV virus fish Unfortunately, this disease has recently spread to the Great Lakes region but scientists are still unsure how it is transmitted. In a recent paper in the Journal of Aquatic Animal Health, researchers at Cornell University tested the idea that perhaps the virus can be transmitted when fish eat infected fish. The scientists fed VHSV-positive Fathead Minnows or Round Gobies to Tiger Muskellunge and compared their infection rate to other Tiger Muskellunge who just shared water with infected fish for 30 minutes or were fed uninfected minnows. While 6 out of 16 Tiger Muskellunge who ate infected Fathead Minnows caught the virus, only 1 out of 16 Tiger Muskellunge who shared water with infected minnows tested as positive, and none of the Tiger Muskellunge fed uninfected minnows were positive. The only similar studies were performed back in the 1980s, when VHSV-infected pike fry were fed to adult pike and 30% of them died within two weeks.  No Tiger Muskellunge caught VHSV from the Round Gobies, possibly because they were infected with a much lower dose of the virus. The authors conclude that predation of baitfish like minnows may be a significant factor in transmission of VHSV and its continued persistence in the Great Lakes ecosystem. Experimental Transmission of VHSV Genotype IVb by Predation, by Rodman G. Getchell, Emily R. Cornwell, Geoffrey H. Groocock, Po Ting Wong, Laura L. Coffee, Gregory A. Wooster, and Paul R. Bowser. Journal of Aquatic Animal Health 25:221-229.