Potential Reservoirs and Risk Factors for VHSV IVb in an Enzootic System: Budd Lake, Michigan.
Viral hemorrhagic septicemia virus genotype IVb (VHSV IVb) has caused major, sporadic fish die-offs in the Laurentian Great Lakes region of North America since 2005. Presently, factors affecting VHSV IVb persistence in enzootic systems are not well understood. Even with annual surveillance, the virus can go undetected for several years after an outbreak before again re-emerging, which suggests that the virus is maintained in the system either below detectable levels or in untested reservoirs. The aim of this study was to identify potential reservoirs of VHSV IVb in Budd Lake, Michigan; VHSV IVb was first detected in Budd Lake in 2007 but remained undetected until 2011. Additionally, we explored the susceptibility of naive fish introduced into a water body enzootic for VHSV IVb by stocking age-0 Largemouth Bass Micropterus salmoides at varying densities into enclosures in the lake. The virus was not detected among samples of the fishes Notropis spp. and Lepomis spp., cylindrical papershell mussels Anodontoides ferussacianus, leeches (subclass Hirudinea), sediment, or water. However, the virus was successfully isolated from amphipods (family Hyalellidae) and Largemouth Bass held in the enclosures. Our finding of VHSV IVb in Hyalellidae amphipods in combination with other research that has detected the virus in Diporeia spp., a large benthic amphipod important as a food resource to Great Lake fishes, suggests that benthic macroinvertebrates are a reservoir for VHSV IVb in infected systems. If there are environmental reservoirs for VHSV IVb in infected systems, they are likely unevenly distributed. Findings of this study add to our understanding of the seemingly complex ecology of this deadly and economically detrimental virus. Received February 22, 2016; accepted October 16, 2016.
a Department of Fisheries and Wildlife , Michigan State University , 480 Wilson Road, East Lansing , Michigan 48824 , USA.
Elizabeth
E
Throckmorton
b Quantitative Fisheries Center, Department of Fisheries and Wildlife , Michigan State University , 293 Farm Lane, East Lansing , Michigan 48824 , USA.
Travis
T
Brenden
a Department of Fisheries and Wildlife , Michigan State University , 480 Wilson Road, East Lansing , Michigan 48824 , USA.
Amber K
AK
Peters
c Michigan Department of Natural Resources , Post Office Box 30028, 525 West Allegan Street, Lansing , Michigan 48933 , USA.
Tammy J
TJ
Newcomb
d Michigan Department of Natural Resources, Fisheries Division , Post Office Box 30446, Lansing , Michigan 48909 , USA.
Gary E
GE
Whelan
a Department of Fisheries and Wildlife , Michigan State University , 480 Wilson Road, East Lansing , Michigan 48824 , USA.|e Department of Pathobiology and Diagnostic Investigation , Michigan State University , 1129 Farm Lane, East Lansing , Michigan 48824 , USA.
Mohamed
M
Faisal
D000818:Animals; D004197:Disease Reservoirs / Q000662:veterinary / Q000821:virology; D005399:Fishes; D005618:Fresh Water; D006114:Great Lakes Region; D060106:Lakes / Q000821:virology*; D008824:Michigan; D029141:Novirhabdovirus / Q000302:isolation & purification*; D012307:Risk Factors