Enough already of the wild birds witchhunt! When even experts are reduced to looking for an "avian version of the Stealth Bomber", it's clear there should be more focus on another potential culprit for harbouring and spreading H5N1. Farming, for instance.
Suppose we could interrogate farming, what might we ask. Let me count the questions. (Others may think of more.)
Six main questions here:
1) Why does the poultry industry continue to spawn highly pathogenic avian influenzas? 2) What role might poultry vaccines play in sustaining and spreading H5N1? 3) What roles might transport of poultry and other captive birds, and poultry equipment, play in spreading H5N1? 4) Does chicken manure - especially chicken manure used in fishponds - play a role in spreading H5N1 beyond poultry farms? 5) Do officials tend to play down or not report H5N1 outbreaks resulting from poultry industry, but readily blame wild birds? 6) Is there an FAO report into the role of farming in the recent spread of H5N1; and if not, why not?
1) We've known for years that poultry farming can spawn highly pathogenic avian influenzas. Strains that are of little or no consequence in wild birds can evolve to become highly lethal to poultry, and to other species - rarely including humans.
Why, then, do we continue to see such virulent strains evolving in poultry farms; why aren't we seeing efforts to transform poultry farming techniques? (Seems it's too late to guard against wild viruses entering poultry)
2) Until H5N1, eradication of infected flocks has been the main means of eradicating HPAI; but with H5N1, poultry vaccines are being widely used. What roles - if any - are poultry vaccines playing in sustaining and spreading the nasty H5N1 variant (genotype Z and near allies)?
Even with good vaccines, infected poultry can retain H5N1, but at levels below those needed for transmission (presentation by Robert Webster). With substandard vaccines, poultry may not show symptoms, but may harbour H5N1 at transmissible levels, thus promoting spread in live markets.
To what extent has the use of vaccines enabled the "Z" H5N1 to survive for nearly a decade - perhaps mostly as a "silent epidemic" (New Scientist)? Does H5N1 survive like a peat fire - mostly almost unseen, but flaring up when into susceptible populations, whether unvaccinated poultry or wild birds?
Where are vaccines used, both iegally and ilegally [eg poultry vaccines have been smuggled into Thailand]; and to what extent are substandard vaccines used? [In China, vaccination reportedly cheaper than using antibiotics, so surely tempting for at least large-scale farmers elsewhere]
Correct use of poultry vaccines should include deployment of sentinel birds - non-vaccinated poultry, in case H5N1 is indeed present (and even spreading). Are these indeed always used in conjunction with vaccines - or are there "accidental sentinels" - non-vaccinated poultry, wild birds.
3) Previous studies have shown that avian influenzas can be readily transported within the poultry industry (an FAO document suggested that once bird flu enters poultry, the mode of transportation shifts "from the flyways to the highways and byways") What movements of poultry (and captive birds that may be directly or indirectly infected by poultry) may be involved in spread of H5N1? What is known of legal movements: how extensive, what are the key routes?
What of illegal poultry/captive bird movements? With Italy recently seizing a consignment of smuggled Chinese poultry including 36,000 duck eggs, these may be extensive. How easy is it to take, say, eggs across international borders?
What, too, of special cases such as fighting cocks, implicated as partial culprits of h5n1 bird flu spread in Thailand? To what extent are vaccinated poultry (including those given substandard vaccines) traded in markets, moved along legal and illegal trade routes?
As well as eggs and birds, even poultry equipment such as crates contaminanted with droppings can spread avian flu. How extensively are these moved?
4) Is there a link between use of chicken manure, including in aquaculture, and spread of h5n1 beyond poultry farms?
How widely used is chicken manure as fertilizer/feed for aquaculture? After recent news report told of chicken manure being dumped by the truckload in a lake in Vietnam (at least 100 tonnes of chicken excrement a day), to increase fish production, cursory enquiries revealed it is also used in Yugoslavia,
Might H5N1 infected chicken manure be the cause of the deaths of mute swans in Croatia, and perhaps Romania? In Croatia, swans that were evidently healthy during a prior stopove in Hungary died after landing on fishponds. In Romania, a BBC news report included, "like the fish farm behind Maliuc, where 86 dead swans have been found in the last week alone."
5) Is there a strong tendency for local and even national officials to play down or even fail to report outbreaks in and resulting from poultry farms - but a willingness to quickly blame wild birds (with or without any actual evidence)? If so, does this significantly distort the picture regarding the true major culprit for sustaining and spreading H5N1 (genotype Z)?
6) FAO has produced a report into the apparent role of wild birds in the spread of H5N1. Why - to my knowledge - is there no equivalent FAO report on the role of farming?
Post edited by: martin, at: 2005/11/12 03:09