#4096
imported_Martin
Participant

Rather odd situation, with Deborah MacKenzie of New Scientist – now gungh-ho re blaming wild birds for spreading H5N1 it seems (see also thread New Scientist dodgy re H5N1 spread to Europe – has confidently written of wild ducks carrying H5N1 to Nigeria, even though (as yet) not one wild bird in Africa has tested positive for H5N1.

Nial Moores of Birds Korea sent Deborah an email, questioning this; cc’d me, and Deborah has replied, likewise including me among recipients. Interesting email from her – indeed plausible that ducks from H5N1 hit areas in summer may have arrived in Nigeria for winter.

But, well, here’s email I’ve sent her:

Thanks for the email; glad you are willing to look at this in some detail. However, your argument is not solid. And, curiously, you ignore the absence of H5N1 across a swathe of land, from Iran east to Japan, where most of north Asia’s waterbirds winter, yet there are no outbreaks in migratory wetland birds. Hong Kong is a notable site here: has some 50,000 waterbirds, including pintail (garganey pass through on migration): not one healthy wild bird has tested positive, among over 16,000 [by some reports; PNAS for some reason gives 13,000 I think, without re-checking.] Currently getting H5N1 in birds, inc poultry; maybe after higher poultry demand at Chinese New Year; and mentioning this, seen report that Nigerian smuggling can increase around Hajj. Hong Kong is at a crossroads for migrants in southern China, right at the epicentre of H5N1 outbreaks. Had H5N1 in birds, inc two urban parks (ornamental waterfowl, at least 2 wild little egrets, which likely residents). So, blithely ignoring not easy. Further, PNAS paper is overall strongly counter to ideas wild birds spread H5N1. Witness regional forms of H5N1: if wild birds could indeed carry and introduce to poultry (and do so readily), why do we see these? It seems curious logic to say poultry trade spreads over short distances, but wild birds over long range.

There is long distance trade, inc smuggling – cf large batch of smuggled poultry from China arriving in Italy. "one detects the presence of the virus chiefly because it causes outbreaks in poultry if the wild birds contact them" – wild birds contact poultry? Where? [maybe it does happen in Nigeria – but people hunt waterbirds there, so might figure wild birds avoid humans as much as possible] "The ducks themselves, at least those that made it through migration, dont die of it, so you wont see it that way." – questionable; are ducks that die of it, plus can get significant death rates – very high in Qinghai – in birds sharing wetlands with them. "A very low prevalence of sampling, if there is even that, cannot prove absence," No need for sampling at Qinghai – the virus made its presence very clearly known. Elsewhere, it is scarce or rare in wild; get some die-offs but need monitoring to find them.. "Flu is highly contagious. It spreads from bird to bird." Ah, now here’s an important one. You refer to "flu" – and make this rather casual statement. Regular wild bird flus do indeed seem highly contagious, among waterbirds (with caveats; seasonal changes, can get variations depending on bird type). But, evidence is that H5N1 in wild birds is not highly contagious. Qinghai the exception. But otherwise, we don’t see H5N1 readily spreading among wild birds. Hong Kong again – has had dead waterbirds found at/near wetland with the waterbirds, but no spread. (Just lately, a dead little egret a few km from Deep Bay.) Mongolia’s Erkhel – "the disease appeared self-limiting in wild birds", researchers had to look hard to find it., and then o only in dead birds Thailand openbill storks – only few amongst large numbers of birds Romania: infected swans on ponds did not infect other waterbirds sharing ponds (this by lack of deaths, also as several of these birds tested)

Romanian swans excreting low amounts of virus. Webster’s ducks with H5N1 that didn’t readily kill them likewise excreted low amounts; High amounts respiratory tracts – but ducks not prone to sneezing/French kissing.

"Selling their birds off at market is what they are reportedly doing even now." – so, do you think others with infected birds, or near infected birds, might have sold them off at markets? To people from non-infected areas. Nigeria had banned poultry imports; yet domestic demand surely still there. Surely tempting to smuggle in birds at bargain prices.

"especially the Z genotype that has been responsible for virtually all commercial poultry outbreaks in east Asia" – This is the Z genotype. One of its variants, but it’s Z. " birds at Poyang Lake in southeast China in March, some of which migrated to Qinghai." – Which ones migrated this way? I know of none that migrate Poyang to Qinghai. I’ve studied some of the Poyang winter birds on migration along east coast of China (can be certain re Siberian cranes) – a long way from Qinghai. [I’ve asked Guan Yi and Robert Webster just which species they say migrated; so far, just told "migratory ducks". Detail is important with virology; also important here re wild birds.]

"timing of the outbreaks in Siberia, Turkey, the Black Sea and Nigeria exactly fit the known movements of some species" Not so with the timing of the outbreaks in Siberia. Link from Qinghai to Siberia doesn’t work: especially timing, in July, when birds from Qinghai not migrating north [many of geese flightless at this time]

"They are kicking birds around because they are rural people, that is how that culture treats animals," – how astonishingly patronising. I have seen rural people interacting with wild birds; maybe hunt n trap and so on, but never this. New Scientist not read there, perhaps, but New Sci taken as authoritative, reaches newspapers and other media

"Were there geese, which do die of this virus, at Poyang as there were at Qinghai?" – Yes, many thousands, including much of world population of swan goose. Also geese, cranes etc. All sharing shallow wetlands, at high densities.

"the Poyang and Qinghai viruses differ from any that have ever been seen in poultry in China." By no means all poultry in China have been tested. Witness PNAS – north China, inc between Poyang and Qinghai, just a blank on the map. I’ve asked Guan Yi; they lack data. So, you are only making guesses re virus in poultry n China. The team found 4 distinct forms in mainland China (seen Guan mention 250 strains); how to be certain a form in north isn’t as per Qinghai?

"The commercial transport of poultry should transport genotypes pretty much at random – smugglers dont genotype infected birds before they ship" – Why at random? If birds from n China to Russia/Kazakhstan, and then onwards by transport links such as railway – and the timings indeed fit this pattern too – would be same strain.

"the only spread long distance so far has coincided with migratory pathways, " Not so; has been spread to Indonesia, Tibet (one case traced to poultry shipped 1500km, Lanzhou to Lhasa), more recently the spread to Russia and so on. Again, it baffles me why this notion re long distance spread by wild birds, short distance within poultry trade. This is not borne out by bulk of PNAS paper – notice re an introduction to Vietnam, evidently by transport from China. But, convenient for officials. [cf with foot n mouth; reached continent from UK – but there, no flying cows as convenient scapegoats]