Sunday, July 14, 2013

Potential Hot Spot for Avian Flu Transmission Identified in Western Alaska

From USGS News Release:

ANCHORAGE, Alaska — Low-pathogenic avian influenza viruses with Eurasian genes have been found among birds in the Yukon-Kuskokwim Delta of western Alaska, supporting the theory that the area is a potential point of entry for foreign animal diseases such as the more highly pathogenic H5N1 strain, according to a new study by U.S. Geological Survey scientists.

The Yukon-Kuskokwim Delta is an important breeding ground for many bird species and is located where multiple migratory flyways converge, providing opportunities for avian pathogens to spread. Among these pathogens are H5N1 avian influenza, which occurs in both low-pathogenic and the more dangerous highly pathogenic forms.  

After the outbreak of the highly pathogenic H5N1 strain of avian influenza in wild birds of China in 2005, the USGS and the U.S. Fish and Wildlife Service, in cooperation with the Yukon-Kuskokwim Health Corporation,  the Kawerak Tribal Corporation and other partners, conducted four years of testing wild migratory birds in western Alaska for the highly pathogenic H5N1 strain. 

In a paper published by the USGS and the USFWS scientists no highly pathogenic forms of avian influenza were found in more than 24,000 samples tested from 82 species on the Yukon-Kuskokwim Delta from 2006 to 2009, however, 90 low-pathogenic strains of the virus were obtained from these Alaskan samples.  Low-pathogenic avian influenza viruses are common among wild birds and do not cause mortalities to the degree often seen with highly pathogenic forms of the virus, said USGS research geneticist Andrew Reeves, lead author of the paper. The significance of this study is that it demonstrates that viruses with genes of Eurasian origin can enter North America via migratory birds. 

In addition, researchers discussed how low pathogenic virus samples from birds further from Asia contained fewer genes attributable to Eurasian strains.  

"This finding supports a 'dilution-by-distance' idea we've hypothesized in other studies," Reeves said. "Birds sampled further from Asia, such as in the lower-48 United States, very rarely contain avian influenza viruses with Eurasian genes, but in Alaska they are more common."  

"Many of the bird samples used in the study were provided by subsistence hunters in 11 villages throughout the Yukon-Kuskokwim Delta who collected samples from many species, including ducks, geese, swans and shorebirds," said Kim Trust of the USFWS.  

"Without our partners in western Alaska, we would not have the robust data set that supports the findings in this paper," Trust said.  

Reeves added that the current study provides support for retaining the Yukon-Kuskokwim Delta as a high-priority region for the surveillance of potentially harmful avian pathogens. 

The paper in the Journal of Wildlife Diseases, "Genomic analysis of avian influenza viruses from waterfowl in western Alaska, USA," by Andrew Reeves, John Pearce, Andrew Ramey, Craig Ely, Joel Schmutz, Paul Flint, Dirk Derksen and Hon Ip of the USGS and Kimberly Trust of the USFWS, is available online.

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Saturday, July 13, 2013

A Conversation About MERS Coronavirus: Dispatch Radio

With the latest case count of Middle East respiratory syndrome coronavirus (MERS-CoV) now standing at 80, there has been a great deal of attention given to this relatively new viral outbreak.

On the Saturday, July 6 Dispatch Radio program, I had the opportunity to talk to Professor of Microbiology and Immunology at Columbia University, Dr. Vincent Racaniello, about MERS.
Listen to the podcast here. The interview starts at the 23:10
There has been a lot of comparisons between the MERS coronavirus and the related Severe acute respiratory syndrome (SARS) that sickened over 8000 and killed 775 a decade ago. I asked Dr. Racaniello to explain the difference between the two viruses concerning  ability to cause disease, how lethal they are and human-to human transmission.
Racaniello says SARS appeared in China in 2003, infected thousands, killed nearly 800 and “then for reasons we still don’t understand, it disappeared.”
That virus [SARS] was not bad at spreading among people, 10% lethality, which is high. About a year ago, a new coronavirus emerged in the Middle East, the MERS coronavirus.
“So far it’s not particularly good at spreading person-to-person, with about 80 infected, Racaniello adds.
However, he does point out that the data is not really available to clearly answer that.
With the numbers of MERS cases at 79 (at the time of the show), I asked Racaniello if he thought the numbers may be higher due to undetected cases.
“Absolutely, he said. I think that the 79 cases are the ones where the people have got very sick, they’ve gone into hospitals and they’ve been diagnosed with this virus infection.
“With most viruses, many, many people get infected and have either mild symptoms, so they never go to a health care provider, or they have no symptoms at all and we have no way of detecting that for the MERS coronavirus yet because we don’t have the right diagnostic test.
“But as soon as those are developed, then we can go out into populations and say, how many people are in fact infected, and it could be that thousands of people have been infected with very little disease, which of course would bring the mortality rate pretty far down.”
Concerning the source of MERS, some have attributed it to bats, at least one report suggested a link with camels. “The bat story comes from the fact that when you sequence the genetic information of viruses and tell which are related to other viruses.
“The closest relative of this virus, aside from other coronaviruses that infect humans, is a virus isolated from a bat in 2008. It suggest, but it doesn’t prove, the virus may have originated in bats. SARS coronavirus originated in bats as well.
“Bats harbor a lot of diverse coronaviruses so it wouldn’t be unusual the virus jumped from bats, he said. People in general don’t really contact bats very frequently, so the idea that there is an intermediate animal went through. In the case of the SARS coronavirus, we think the virus went from a bat, to a Palm civet then to people, and it could be that in this case with the MERS coronavirus, it originated in bats, and it may being going through camels, as there has been reports of individuals getting sick after being close to camels.”
However, Racaniello points out that there are many cases where patients don’t have a contact history with animals of any kind. “So you have to wonder if the virus isn’t spreading in people already”, he adds.
I asked Racaniello about the diverse conclusions and statements from scientists from the Pasteur Institute in France who suggest that MERS-CoV does not yet have pandemic potential, and the statement in May by  WHO Director-General Dr Margaret Chan at the 66th World Health Assembly (WHA) who stated, “The novel coronavirus is a threat to the entire world.”
Who is closer?
“I think the Pasteur scientists are probably closer, Racaniello answers. Listen, it’s infected 80 some people, in the scheme of the world, this is not very much.
“As far as we know, this virus can’t spread efficiently among people so that’s why we say it doesn’t have pandemic potential.”
Racaniello does note that Dr. Chan is speaking as head of WHO and has to be very cautious. “If this virus somehow changed, it could acquire pandemic potential, so she’s sending out a message to health organizations globally that we need to keep an eye on this virus and get ready in case it should get more serious.”
The question, What is the threat of MERS entering the United States and are we prepared? was posed to the professor.
“That’s a very interesting question, I think it might of already come into the US, with global travel being as easy as it is. It’s very easy to imagine that someone has been infected in the Middle East, has no fever, no symptoms, has flown to the US shedding virus on the plane and within the US.
“So far, we don’t have any evidence that’s happening, but it certainly could be going on and we wouldn’t be able to detect it, especially if people haven’t been sick yet.
“It’s quite likely that the virus is here already, or will soon be brought into the US. Then the question would be, what would happen?
“Like we’ve seen in the Middle East, mainly really sick people have been infected with this virus, so you could imagine the same happening to a very sick person here in the US. You might get a few cases here of infection and that would trigger a lot of panic I think.”
Racaniello says, “Unfortunately, we don’t have any therapeutics for it–we don’t have a vaccine, we don’t have any antiviral drugs, the best we could do is try to limit people traveling and interacting with one another. But as you probably could guess would be virtually impossible.”
Without vaccines or antiviral drugs, it’s really hard to stop viral spread.
“I would guess if this virus came in to the US in a form that could transmit effectively among people, it would spread pretty efficiently. The good news is that hasn’t happened yet, even with global travel”, Racienello said.
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