#4062
Martin W
Participant

comments re this grebe and some other wild birds in Russia that were reported to have H5N1
First by Richard Thomas of Birdlife International;

Quote:
> >[Readers are referred to 2 drafted scientific papers from the D.I.
> >Ivanovsky Institute of Virology, Russian Academy of Medical Sciences. The
> >papers have been opened for discussion at:
> >.
> >
> >The papers include details on “indication of influenza A/H5N1 virus by
> >RT-PCR of cloaca/trachea samples” from 5 species of wild birds “without
> >clinical features”, collected near the center of the epizootic in the
> >Novosibirsk region (July 2005).
> >
> >The birds were: Mallard (_Anas platyrhynchos_), 6/12 positives; Pochard
> >(_Aythya ferina_), 12/33 positives; Great crested grebe (_Podiceps
> >cristatus_), 1/2 positive; Coot (_Fulica atra_), 0/5 and Common tern
> >(_Sterna hirundo_), 0/2. Out of a total of 54 non-clinical wild birds, 19
> >(35.2 percent) were positive.
> >
> >The papers also report the isolation of the A/H5N1 strain
> >A/Grebe/Novosibirsk/29/05 from a Great crested grebe “without clinical
> >features”, collected near the center of the epizootic in the Novosibirsk
> >region (July 2005). – Mod.AS]
>
> I strongly urge you to read the above papers – and please comment.
Needless to say the blame is laid firmly and squarely on wild birds. There’s
some very important information lacking from the papers, but some very
interesting information included too.
>
> Particularly lacking is any indication as to how the poultry and wild
birds came into contact. I also couldn’t see any indication of timescales of
the episode: clearly poultry were dying before wild birds became infected,
and it is stated many wild birds later died, but it doesn’t say how long
afterwards.
>
> I am particularly amazed to see that just over a third of the wild birds
tested were positive (more than 95% of the poultry were positive). There is
some analysis of the genetic strains involved. Of particular interest is
that the strain in poultry is said to be very close to the Qinghai strain.
This means that the strain from the Qinghai area was transported to
Novosibirsk by some means. Given the location, time of year and lack of
spread in other directions from the Qinghai area, wild bird
migration–whilst it can’t be ruled out–would seem to be highly unlikely.
>
> Hence, poultry or something that had come into contact with infected
poultry/faeces in the QInghai area is far more likely. A quick look at the
atlas and you will see Novobirsk is on a railway connection to Lanzhou, the
large city close to Qinghai.
>
> Interestingly, FAO has reported Lanzhou as the source of an avian
influenza outbreak in Lhasa, in January 2004 – hence there is already a
precedent for long distance movement of infection from the Qinghai region
(Lanzhou to Lhasa is 1,500 km). The Lhasa outbreak was actually at a poultry
market. [Imagine if those birds hadn’t died at the Lhasa market, but had
been bought by several farmers/local people in the region. We’d have a
sudden near simultaneous outbreak across farms/backyard chickens in Tibet. I
wonder where the blame for the outbreak would be placed?]
>
> There is no indication in either paper as to whether the poultry involved
were recently transported to Novosibirsk, bred locally or purchased at a
poultry market supplied from elsewhere. This should be investigated, as
should other possible links – perhaps through infected animal/fish-farm
feed. I’m sure you’ll not be surprised to learn that Lanzhou is a major
producer of feed too.
>
> Cheers
> Richard

a response to this, from a virologist:

Quote:
I am afraid one possiibility for many positives in the wild bird species is cross contamination and false positives when PCR alone is used to identify infection. An aliquot of the cloacal sample could be sent to another laboratory for verification.

Post edited by: martin, at: 2006/01/30 07:43