From Nial Moores
Dear Pro-Med, Aiwatch, colleagues,
As a bird researcher and professional conservationist living and working in South Korea, I am writing again, in response to a very recent posting on Pro-Med, reproduced on AIwatch (pasted below).
The Pro-Med mailing group is perhaps the single most important source of up-to-date medical information on H5N1, and I therefore wish to express sincere thanks to Pro-Med for maintaining this information flow. Because of my respect for the mailing group, I have mailed on a couple of past occasions the kind of information that has been requested by the group: e.g. specific information on species of birds.
Up to now though, it appears that this information has largely not been posted; nor perhaps has it been taken particularly seriously. For example, although I recently mailed to Pro-Med about the three species of magpie that are actually found in Liaoning Province (the area of one outbreak in NE China), Pro-Med then apparently decided not to include that information, but instead to expand their inquiry to include several more species of magpies, even forest-dwelling species from Indo-China (because they are listed on the Avi-Base list for "China"). Please be aware: ALL of these magpie species are non-migratory; Eurasian Magpies Pica pica however have been infected before by H5N1 (in South Korea); they are scavengers often found around poultry farms etc and they are abundant in that presently-affected part of China.
Moreover, I outlined in my last mail (which I hope was received: it was apparently not posted) four broad categories that might help in the consideration of spread (local or otherwise) among wild bird species. These are:
Domesticated/caged wild birds;
Scavenging species (e.g. Crows, Eurasian Magpies);
Species that often feed in polluted waterways near towns, farms, sometimes also scavenging on dead animals (e.g. Grey Heron, Little Egret, Chinese Pond Heron, Black-headed Gull etc);
Colonial nesters/flocking waterbirds (e.g. Bar-headed Goose, Great Cormorant etc).
These categories might well produce a more useful tool for considering infection in wild birds than by looking at the purely species or genus-level.
For many ornithologists (not all), long-range spread of H5N1 by wild birds remains but a poorly supported hypothesis; spread by wild birds to poultry apparently remains even less well-proven; local infection of wild birds by poultry or poultry products appears proven beyond reasonable doubt (e.g. dead wild birds found near affected poultry farms comprised e.g. non-migratory Large-billed "Japanese" Crows Corvus macrorhynchos in Japan; non-migratory Eurasian Magpie Pica pica in South Korea).
Information on the other hand from affected areas of Russia of "hunted" wild birds testing H5N1 positive apparently does not include information on the particular type of H5N1; even on whether the birds were showing signs of illness or not when hunted (and it is indeed surely reasonable to assume that sick birds will more easily be hunted than healthy ones). In this form, this "evidence" surely does little to prove that healthy wild birds can carry and spread HPAI H5N1 (all the more when it was set in the context of trying to prove such a connection: an obvious attempt at self-fulfilling prophecy): and yet this is somehow used as some kind of proof by many.
Rather, the news posted on Nov 5 on Pro-Med, showing that the virus found in a DEAD Grey Heron in Romania very closely matched that found in poultry in Novosibirisk, DEAD wild birds (and presumably poultry) in Qinghai (with these in turn linked back to earlier outbreaks in Chinese poultry), Turkey and previous Romanian isolates is all CLEAR evidence of a link.
Is it fair to suggest that there are perhaps only three likely causes of this link, of movement of the virus between these geographically well-separated areas?
Spread by movement of infected poultry or products, caged birds etc;
Spread by wild birds;
Spread by both wild birds and movement of poultry and products etc.
The first mechanism, spread by movement of infected poultry and products or caged birds, has been proven many times in earlier outbreaks of HPAI, and also of HPAI H5N1.
The second (and third), - involvement of wild birds in a wide geographical spread - surely requires a migratory bird able to carry the virus long distances, huge distances.
Simple question: What wild bird species migrates in that way? From SE China to NW China, to Southern Russia, then direct to Turkey and Romania.
Simple answer: none.
The possibility has therefore been suggested that the disease might be being spread in relays by wild birds. This too is a hypothesis worthy of consideration, but it seems rather weak from the outset.
Please consider the following:
Many wild birds (individuals and species) seem susceptible to HPAI H5N1, and many wild birds are killed by it. Outbreaks like Qinghai, which killed thousands of waterbirds, and lack of evidence of H5N1 in tested healthy wild birds, suggests this virus remains for now highly pathogenic to wild birds.
Many waterbirds concentrate at favored wetlands;
Many migrant species re-use favored staging sites seasonally;
Many bird species occupy broad zones for breeding, such as alpine and tundra habitats, e.g, from northern Scandanavia all the way across to NE Siberia, then move more or less the shortest distance post-breeding to winter in more temperate zones (better understood by looking at species' ranges mapped on globes rather than flattened maps). Many populations and species from different flyways therefore mix during at least some part of their biological cycles.
Wild bird HPAI H5N1 carriers would surely repeatedly come into contact with susceptible, uninfected wild birds, from their own and other flyways, and infect them, creating a relay effect. However, if the carriers were indeed still able to migrate say north to breeding areas, they then should also be able to migrate back south to their original wintering areas via regularly used staging sites, or at least would come into contact with others of the same populations that would migrate back along the same route, creating further outbreaks en route and back at or near the site of original infection. This would create a pattern of multiple outbreaks spreading along different flyways, in different directions, more or less simultaneously. Less of a single relay, and more a series of relays running simultaneously.
Over time, spread by wild birds would thus very likely create a recognisable pattern of outbreaks.
These outbreaks likely:
Would involve frequent, either recurrent or persistent outbreaks in wild birds, at key sites;
Would involve whole flyways with such outbreaks in wild birds at key sites;
Would likely involve rapid spread to other flyways remote from the Eurasian landmass - into African and American Flyways etc;
Would at the least involve some mirror image of wild bird outbreaks (e.g. outbreaks in SE Europe matched by outbreaks in E Asia), as birds move SE and SW from infected breeding areas.
This is not at all the pattern that is yet emerging, however. Spring outbreaks in Qinghai in 2005 were not repeated in autumn; birds breeding at Qinghai, now wintering in India and elsehwere , have not been identified as the cause of new outbreaks; wild bird outbreaks have so far not been shown to be persistent or repeated; there have been absolutely no mirror outbreaks, no outbreaks in wild migratory bird species in East Asia to match those in SE Europe this autumn; no spread yet identified to other continents away from the Eurasian landmass. And yet it is already November, when much of the main autumn, southward migration of waterbirds from Siberia has already passed its peak....
Is it not right to ask therefore: Why have no such patterns evolved, even since the first related outbreaks of HPAI H5N1 in 1996/1997? Don't contemporary outbreaks instead still seem to match better spread from one, or now two, main poultry disease epicentres, as depicted by Shortridge and Melville in Lancet in 2004?
Simplistically put, cannot the present pattern still be typified as one largely of: disease endemic in poultry; movement of infected poultry to largely uninfected areas; local infection of environment or wild birds by said poultry; resultant outbreak in wild birds; death of wild birds; end of outbreak in wild birds; local culls of poultry; persistence in regional poultry.
Surely, for scientists negative data (i.e lack of patterns in wild bird spread) should have considerably more value, or at least as much value, as poorly-detailed and heavily biased reports, often verging on the level of anecdote?
However, the absence of patterns which can be hypothesised to be made by spread of H5N1 by wild birds has seldom been seriously refered to, if at all, by Pro-Med or other responsible media.
Recent discussions too in a variety of media on the outbreak in Croatia with its Mute Swans has failed to highlight recent information that the bird whilst banded in Hungary appeared fit; that the outbreak was confined to a fish-farm. It has not (as far as I am aware) included intensive inquiries by the medical community on the possible use of chicken manure and other poultry products as fertiliser for fish ponds...Rather, the focus has stubbornly remained on trying to find which wild birds might be the carriers.
Respectfully, a Pro-Med moderator asks for a bridging of the gap " between virologists, epidemiologists and ornithologists." For this to be better achieved, everybody needs to step back, and start again looking at the spread of H5N1 with a fresh and open mind: this will surely be invaluable in finding ways to help stop the spread of this disease. There is a need to look closely at local environmental factors (yes, including to keep considering how poultry and poultry products might be infecting given locales), and also to ask why outbreaks in wild birds seem to peter out over time?
Respectfully too, those on this list and elsewhere need to to consider openly the evidence provided by a fair number of ornithologists that suggest local infection of wild birds by poultry still appears to remain the most probable source of infection in wild birds in almost all cases up to the present (the one obvious exception for now remaining the outbreaks in Mongolia in late summer 2005: short-lived as they were).
If relevant persons start to approach H5N1 outbreaks in this way, appealing for wider information on a variety of environmental factors, incorporating information provided by ornithologists and others that are aiming also to search out real causes, then surely we will all feel the gap being bridged - as it absolutely needs to be.
Let us work more closely together, promote biosecurity and changes to the inhumane treatment of poultry and caged birds, to benefit wildlife as well as poultry and people, and cut through some of these myths.
Nial Moores, South Korea
Director, Birds Korea