Emerging infectious diseases don't appear out of thin air. Mostly (75%), they come from animals. In the language of science, they are zoonoses. So veterinary pathologists see themselves on the front line of early warning against emerging disease and runaway pandemic disease. Consider bird flu:
So is the threat real? "Whether the bird flu virus will spread to North America is unpredictable at this time," says Corrie Brown, Diplomate of the American College of Veterinary Pathologists (ACVP) and a University of Georgia professor of veterinary medicine. "Although the likelihood of this mutation is unlikely, history cautions us to the possibility. The longer the bird flu virus is in circulation, the greater the risk for a pandemic." (PharmaLexicon)
Hmmm. Possible but not likely but we can't predict. OK. Not sure what the evidence for the likelihood estimate is, but I'll take that as an expression of professional judgment. Here's some more:
Most emerging diseases are infectious with zoonotic (animal-to-human) potential, occurring at the interface between wildlife, domestic species, and humans. Why are zoonotic diseases more prevalent today? The main reasons are:
(1) Increasing numbers of humans
(2) Expanding globalization of trade
The tripling of international commerce over the past 20 years, combined with runaway population growth, has created a synergy for microorganisms to move freely and quickly from their commonly inhabited domains into unexpected niches, often with lethal results.
Wouldn't quarrel with those two points but I'd also add a third:
(3) Increasing encounters of humans with animals they had only rarely, if ever, encountered before. When the rain forests in Indonesia are cut down for wood or agriculture, humans insert themselves into new habitats with new disease reservoirs. Ebola and HIV are likely examples.
The American College of Veterinary Pathologists has its own list of "Bird Flu Facts" and it's interesting to see what they are from their perspective:
- The biggest threat is to the poultry industry
- Reduced production would impact everyone's pocketbook
- The U.S. Department of Agriculture has stringent control measures in place at the borders and is working closely with the poultry industry to boost biosecurity
- We still need to be concerned about it infecting wild birds
- Mortality of mute swans, ducks, geese, raptors and other wild species associated with the bird flu virus infection in Europe has led to a number of deaths among meat-eating species, including tigers, leopards, domestic cats and humans, who most likely contracted the virus by feeding on carcasses of infected domestic or wild birds
- Risk of human infection with the virus in its current form appears to be quite low, as is human-to-human transmission
- The virus could become easily transmissible among humans through mutation or reassortment with a human influenza virus
Two deserve some mention. There seems to be quite a bit of faith that the US Department of Agriculture is on top of this problem. A General Accountability Office report last week questioned this and the USDA seemed to acknowledge they might not quite "have their ducks in a row" (sorry). The second is the implication that meat-eating species, "including tigers, leopards, domestic cats and humans" contracted H5N1 infections from "feeding on carcasses of infected domestic or wild birds." Do the veterinary pathologists believe there is risk from eating infected poultry? Many veterinary pathologists have poultry producers as clients. I wonder how this slipped by.
Maybe we weren't supposed to notice.
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The risk is from eating raw poultry. If it's handled and cooked properly, there shouldn't be a risk. But with an estimated 2-4 million cases of salmonellosis in the US every year, recommended food handling practices clearly aren't being followed.
Sister H.: There are two issues, here, one of which you have identified. The other is the contention that there is no gastrointestinal route to infection. We discussed all of this here pretty often in the past (didn't provide links because I was too lazy), but you are quite correct in saying that consumers are not necessarily in the clear from infected poultry if they do not handle it properly during preparation. Improper food handling is clearly quite common given the high incidence of foodborne infection in the US.
Revere. Thanks again.
It is the old 'push-pull' thing again...slivers from climbing back on the fence each time H5N1 knocks them off...
...no wonder Regulators and Governments don't believe in the threat...which is kind of funny given the potentials ...
...you got to love human nature!!
"Whether the bird flu virus will spread to North America is unpredictable at this time," says Corrie Brown, Diplomate of the American College of Veterinary Pathologists (ACVP) and a University of Georgia professor of veterinary medicine.
What Dr. Brown is saying I think, is that it is unpredicable whether the bird flu virus will arrive in North America in birds...an interesting statement considering there is a connection in flyways and H5N1 has clearly demonstrated its ability to infect all of the rest of the world in basically twelve months.
I will give her the point however...but then I would ask her how likely it is that H5N1 will arrive with a humans as the vector rather than birds...
...I think if we could get past the 'sound bite' and expand on her view point a bit...the nuance might be quite different.
I don't think any scientist...who does not have a conflict of interest...could look at the last twelve months and not be very concerned...as H5N1 was completely silent last year at this exact time... and stayed quiet until Janurary 2007...in fact the debate from Sept-Dec 2006 was whether H5N1 had gone away and the threat was over.
If the sound bite chosen from an interview is completely non-representative of the overall opinion in the interview...which may have happened in this case...how can the person interviewed correct the situation?
Maybe what we have here could be called a stealth pandemic.The thought of the virus slowly creeping over the world gradually poisoning our environment, and becoming endemic over the entire planet and infecting more and more species is a very scary thought.How would we get rid of it?
"Corrie Brown, Diplomate of the American College of Veterinary Pathologists (ACVP) and a University of Georgia professor of veterinary medicine."
Must have been too busy to have seen this? US already has H5N1.
http://wildlifedisease.nbii.gov/ai/
Of course, for a Highly pathogenic H5N1
avian influenza Early Detection Data System, it is odd the table http://wildlifedisease.nbii.gov/ai/LPAI-Table.jsp
is labelled
"LOW PATHOGENIC "NORTH AMERICAN" H5N1 AVIAN INFLUENZA STRAIN IN WILD BIRDS PRESUMPTIVE AND CONFIRMED TEST RESULTS" so there seems no place to put a "high-path" result- not that the terms have anything to do with whether or not the virus is a danger to humans...
..." If the genetic sequence matches that of a known highly pathogenic AI virus, the sample is considered to be highly pathogenic."...
And, I guess, if they do not have an exact sequence match, they need say nothing??
Or, just; "Low-path: not related to HP-H5N1?"
As if an H5N1 strain and an H5N1 strain are not "related"?
Wayne. Excellent point!!
In my opinion, for what it is worth, there is nothing we can do...it is like a forest fire that gets out of control...it starts feeding on itself.
...it will never go away (like H1N1-1918 that is still with us today)
...it will run until it exhausts all avaliable 'fuel'...
...and that is the difference that makes H5N1 absolutely unique among influenza viruses including H1N1-1918...
...it has the ability to infect all avian species and all mammalian species at the same time...and relatively efficiently...
...and that has never been seen before in any pathogen...as far as I know.
4) Increased number of chickens and other poultry, swine and other domestic animals.
I can't find the exact numbers (I saw them once upon a time) but this is a rough estimate "The number of chickens slaughtered globally has increased by around 15 billion over the past decade." I am sure that means increased by 15 billion per year.
http://www.ciwf.org.uk/campaigns/primary_campaigns/broilersatw.html
Also of surprising note "43% of World's Chicken Come from Brazil"
http://www.brazzilmag.com/content/view/1137/53/
That puts a lot of chicken/people combinations closer to home.
Sister H - when we think of proper food preparation we think of nicely packed breasts and legs of chicken - use a separate board, clean it good etc. What we forget is the people who slaughter them and get them to that grocery friendly state. Easy to forget as they are poor people and increasingly from south of the border (legal and illegal). Given that a poultry processing factory in SC or NC (can't remember) had a fire a few years back and a bunch of people were killed because the exit doors were locked (don't want anyone sneaking out for a break or a cig), I think we can assume that when they hire aliens they are no better and perhaps worse in their push to be "efficient". Thus those folks will have plenty of opportunity to be exposed to all parts of the chickens and turkeys they handle.
Since we slaughter our own chickens I can tell you the beheading, debowling, defeathering, and cutting up process are pretty hard to accomplish without some "improper" handling.
PS to my comment above - one might not care what happens to those aliens chuncking off the heads of the chicken we eat, but the wife of one of the poultry slaughterhouse workers might be a nanny for someones kids and so it goes from the poor to the rich - which is why we need good public health for everyone.
"Nothing we can do"? Maybe we can prepare, to improve our odds. Vitamin D has been reported as protective against seasonal flu, to the point that some speculate that the "flu season" is the "low vitamin D season", due to less UV exposure which photosynthesizes the vitamin. Don't overdo the sunscreen! If you do get sick, having family/friends prepared to care for you might help you survive and recover to care for them.
To the factors mentioned, another must be added. The changes in the ecology of how we raise animals, particularly the relatively recent expansion of large confined animal feeding operations (CAFOs) with tens of thousands of animals densly packed, is an important factor in the story of emerging infectious diseases. These are the sites where the LPAI to HPAI shift is most likely to occur through recombination, for example.
Ron, good point. these large confined operations are now in countries without the will or resources to do good biosecurity. And as we saw with Bernard Matthews, even in countries where the resources are available, the capitalist mindset removes some of the will to practices good biosecurity.