There was a lot of mystery surrounding a disease which was rampaging through European Salmon farms, a disease which was wasting their hearts and muscles. Finally, through the use of Genome sleuthing, the mystery has been solved.

The disease is caused by a previously unknown virus. This identification does not mean that there is now also a cure for the disease, however it is a great step forward into solving the problem. Now that scientists have pinned down the disease and the genome, it is only a matter of time before a cure will be found.

“It’s a new virus. And with this information now in hand, we can make vaccines,” explained director of Columbia Univerity’s Center for Infection and Immunity, Ian Lipkin.

A couple of years ago, some Norwegion fisheries got into touch with Lipkin and asked for his aid in discovering what was going on in their Norwegion Salmon farms. They wanted to know what was causing the HSMI (Heart and Skeletal Muscle inflammation), the scientific name for an affliction which was identified in 1999 on one of their farms.

The fish which are infected are physically stunted, and have muscles so weak that they often have trouble swimming about, or even circulating blood around their bodies. This disease often results in death, so there is a great cause or concern. The reason there is so much concern is that the original outbreak was followed by 417 other in Norway and the United Kingdom, and every year there are more reports of the disease.. What is even more disturbing is that there have been reports of wild salmon being infected, which means that salmon which escape the farm are infecting the already low numbers of wild stocks. If something is not done to fix this problem, it could quite possibly spiral out of control, and have a devastating effect on not only local ecosystems but on the entire salmon market as we know it. “If the potential hosts are in close proximity, it goes through them like wildfire,” said Lipkin.

Lipkin and his team, which have already had great success in identifying mystery viruses, rigorously examined samples taken from infected salmon pens. They were looking for the DNA sequences which resemble sequences found in other viruses, and hopefully finding the HSMI-causing sequence. Lipkin compared the grueling process akin to solving a Sunday paper crossword. The researchers eventually found what they were looking for, and dubbed the virus piscine reovirus, or PRV. The virus was unveiled and explained in the issue of Public Library of Science one, published on the 9th of July.

Some viruses which are rather similar have been discovered on poultry farms, and cause muscle and heart disease in chickens. “Analogies between commercial poultry production and Atlantic salmon aquaculture may be informative,” The researchers wrote in the article. “Both poultry production and aquaculture confine animals at high density in conditions that are conducive to transmission of infectious agents.”

The results from these investigations might just be useful when the Obama administration comes up with its national policy for regulating aquaculture.

For the first time, a viral hemorrhagic septicemia virus (VHSV or VHSv) has been identified in fish from Lake Superior, the largest of the five Great Lakes of North America.

The virus was identified by researchers at the Cornell University’s College of Veterinary Medicine and the finding has also been confirmed by the United States Geological Survey’s (USGS) Western Fisheries Research Center in Seattle.

The virus causes viral hemorrhagic septicemia (VHS) in fish and can result in significant losses in wild and captive raised fish populations.

“VHS is one of the most important diseases of finfish,” says James Winton, a VHSV expert working at the Western Fisheries Research Center. “It not only affects the health and well-being of populations of several important native fish species, but it can also impact trade, and, should it spread into the U.S. aquaculture industry, could do substantial damage as happened in Europe and parts of Japan.”

The infection is one of only nine fish diseases that must be reported to the World Organization for Animal Health. Until 2005 it was not known to exist in the Great Lake system but that year it caused several massive die-offs. Since then the virus has been detected in all of the Great Lakes except Lake Superior, and was for instance the culprit when 40,000 freshwater drums died in Lake Ontario over the course of just four days. In addition to the Great Lakes, the virus is also present in the rivers of Niagara and St. Lawrence and in inland lakes in New York, Michigan and Wisconsin.

Previous genetic research carried out by scientists in Canada and the United States show that the VHS virus was probably introduced to the Great Lakes during the last 5-10 years.

Experts now fear that current federal and state restrictions placed upon the movement of fish and fish products won’t be enough to prevent the virus from reaching native fish in the 31 states of the Mississippi River basin.

A team of U.S. scientists has documented the first transmission of the lethal phocine distemper virus from the Atlantic Ocean to a population of sea otters living along the coast of Alaska.

The presence of phocine distemper virus has been confirmed in nasal swabs take from live otters and through necropsies conducted on dead otters found along the Alaskan coast. The findings also indicate that the virus was passed between seal species across Northern Canada or Arctic Eurasia before reaching the otters in Alaska’s Kachemak Bay.

Prior to this study, PDV had never been identified as the cause of illness or death in the North Pacific Ocean and researchers suggest that diminishing Arctic sea ice may have opened a new migration route for both animals and pathogens.

The study was carried out by researchers from two California universities and the Alaskan branch of the U.S. Fish and Wildlife Service. It has been published in ”Emerging Infectious Diseases”, a journal published by the U.S. Centers for Disease Control and Prevention.

What is phocine distemper virus (PDV)?

Phocine distemper virus (PDV) is a paramyxovirus of the genus Morbillivirus. It is dangerous for pinniped species, especially seals, and is a close relative of the canine distemper virus (CDV).

PDV was first identified in 1988 when it caused the death of approximately 18,000 harbour seals, Phoca vitulina, and 300 grey seals, Halichoerus grypus, in northern Europe. In 2002, the North Sea lost approximately 21,700 harbour seals in new a PDV outbreak – estimated to be over 50% of the total population.

Infected seals normally develop a fever, laboured breathing and nervous symptoms.