When we consider the spread of bird flu, we often focus on the basic reproductive number, R0, the average number of new cases that a single infected individual would produce in a completely susceptible population. But individuals are not the only possible unit of analysis. One could consider infected farms, too. That's what researchers at Imperial College London and the London School of Hygiene and Tropical Medicine did in their analysis of the spread of the H7 subtype (H7N3, H7N7, H7N1) of avian influenza virus in Italy, the Netherlands and Canada. The results of several years of data showed that we are operating at the knife-edge of the threshold of outbreaks in terms of R0:
Dr Tini Garske , from Imperial College London's Institute for Mathematical Sciences says: "Our analyses suggest that in the event of an outbreak of highly pathogenic avian flu in a very dense poultry farming area, additional measures may be needed in order to halt the epidemic. In the case studies we looked at we found that pre-emptive culling and de-population of nearby at-risk areas succeeded in containing the outbreak, where other less drastic measures had failed."In order to analyse the transmissibility of HPAI the researchers estimated the farm-to-farm 'reproductive number' of the virus. The reproductive number is a measurement of how many farms an affected farm infects during an outbreak.
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"We found in our case studies that the average reproductive number, prior to controls, was between 1.1 and 2.4. Although this average did fall when standard measures were introduced, it remained close to the threshold value of 1. Therefore, stronger action may be necessary to ensure the disease is eradicated." (Imperial College, news release)
Bird flu has both a public health dimension and a veterinary/poultry industry dimension. They are connected because this is currently a zoonotic disease, i.e., one endemic in animals that passes to humans. It could become either endemic or epidemic in humans, too, which is the big fear, but a virus that decimates the poultry industry is also a major threat to a source of inexpensive and high quality protein and the economy of many countries and firms. These analyses suggest that controlling the spread of influenza virus in poultry remains a daunting task. We are still not sure how to do it with confidence.
One less talking point for the poultry industry.
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World Bank funds new bird flu plan
This is off the radar in rich countries like the US, but is a huge issue in the developing world (what a hollow ring those words have!)
So Revere do you still say vaccination and culling wont work? It would seem tht this stuff even in the factory farm environments is still able to make it in via feet and/or sale of birds. Its getting in somehow in just about every case.
My big rub with culling is that we pay big bucks to countries in SE Asia to stem the tide and they cull because there is compensation. Then almost immediately on the heels of that, they either start growing or they buy infected breeder stock. Never ending cycle and at some point in time coins are going to stop flowing. The rise in chicken prices worldwide is going up and they are absolutely going to increase the supply via boats in the Java Sea, or by hiding the birds in the boonies to grow more.
I also believe we are now moving into a new phase. That being that culling immediately while very important of infected flocks there will be no compensation. Compensation for birds is stupid and its a bottomless pit. They make more off of the comp packages than they do off the bird normally. And they'll lie here in the US about how many birds. Ever worked on a chicken ranch? I did for a summer and its a nasty business and I couldnt count them accurately within 100. RFID might help but look for this one to spin out of control fast.
There is a whole industry here in the US that is about to take a huge hit if high path BF arrives. Tyson for starts. Its the same as it would be if BSF arrived definitively. Hundreds of thousands of workers in the production, the same in the consumer industry such as McDonalds/Burger King.
They dont want to find it and they arent looking either.
a virus that decimates the poultry industry is also a major threat to a source of inexpensive and high quality protein and the economy of many countries and firms.
And this at a time when the traditional source of inexpensive protein for many Third World countries, oceanic fisheries, are in precipitous decline due to overharvesting.
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This editorial misrepresents the problem as insufficient measures to protect the poultry industry as a food resource. The study says premptive culling works, which is to say that the solution to the problem of the threat to people is NOT protecting the poultry industry from losses. But do we protect human food resources by protecting concentrated production of poultry? Not according to Gates Foundation, which is focused on supporting small farms to end hunger.
The best solution to both hunger and the danger of evolving efficent B2B is to ban concentrated poultry production.
I agree that intensive farming, i.e., concentrated poultry raising is what got us into trouble in the first place. What would be the equivalent of organic bird farming?
Here is a link to description of "organic" meat in Australia.
http://www.chicken.org.au/page.php?id=6
In practice, the prohibition on vaccines for organic precludes concentrated production, while the lesser standard labeled "free-range" only requires that the animals have access to an outside run for some time each day. However, "free-range" is prohibited by many countries on the pretext of protecting poultry from H5N1 from wild birds, even where no wild birds with H5N1 have been detected.