The Viral Hemorrhagic Septicemia virus is just what is sounds like: a virus. Viruses, technically, are not living. Viruses are drifting pieces of genetic material, namely DNA or RNA, that are encapsulated within a protein coat. The do not eat, transpire, or carry out any other metabolic processes attributed to life.

Even reproduction is not a task that a virus can accomplish on its own, which is why it requires a host. For VHS, the hosts in this parasitic relationship are the fish.

Infection of the host begins with contact with the virus. Fish can be exposed to, and contract the virus in a number of different ways. Exposure to feces, urine, or other fluids from infected fish (such as milt) can transfer the virus. The virus can enter into the fish via an open wound or through the gills (though rare), and transfer of the virus also occurs when a fish eats an infected fish. Contaminated eggs can also spread the disease, and bait fish brought in from infected waters can as well. This is a main reason for why local governments are trying to get out the word on VHS, and educate fishermen and other marine life workers.

Photo Courtesy of Physorg.comAfter reaching the fish, the Rhabdovirus (contains negative-sense, single-stranded RNA) then proceeds to infect cells of major organs. The virus uses it’s RNA to force the cell into making more of the virus. When the cell has made enough of the virus, the virus bursts out of the cell, which leads to necrosis (cell death).

 VHS (red) invading Gill Epithelium

This widespread necrosis has very damaging effects on the fish, including hemorrhaging of organs or muscle tissue, and swelling of organs or tissue. Sometimes the effects of the virus can be seen externally on the fish as well, such as red spots seen on the surface of the fish.

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