- "Since the last issue of AIDEnews, outbreaks were
suspected or confirmed in Omsk, Tambov, Cheliabinsk, Altai, Kurgan Regions
in November, and in Kurgan, Astrakhan and Kalmykia Regions in December.
In Astrakhan Regions (in the Volga Delta near the border with Kazakhstan)
and in Kalmykia, around 600 dead swans have been found.
- Research undertaken by the Russian Vektor Center's zoonotic
infections laboratory indicated differences between viruses isolated in
Novosibirsk Region: virus isolated in the summer/autumn of 2005 is almost
identical to the strain that caused an outbreak in northern China in spring
2005 but the virus found in the second outbreak was similar to virus found
in Viet Nam in 2002-2003."
- The above comments indicate that there are now at least
three versions of HPAI H5N1 circulating in Europe. The most common
version is closely related to the bar headed geese isolates from Qinghai
Lake. These isolates have an HA cleavage site sequence of GERRRKKR
which has been reported for isolates in Romania, Turkey, Croatia, Ukraine,
and Russia (Tula). This cleavage site matches earlier isolates from
Novosibirsk, Mongolia, and Kazakhstan and has been associated with wild
bird flu sequences.
- The latest Ukraine OIE report however, describes isolates
that have a genetic background similar to the above wild bird flu isolates,
but with a cleave site of RERRRKKR, which matches the most common cleavage
site in Asia including the original Guangdong goose sequence from 1996.
- The comments above indicate a third H5N1 species related
to isolates from Vietnam in 2002-2003 has been detected in the Volga Delta
region. The earlier Vietnam isolates (A/Chicken/Vietnam/Ncvd8/2003(H5N1)
, A/DuckVietnam/Ncvd1/2002(H5N1)) were also HPAI, but had a unique HA
cleavage site, REIRRKKR, which had also been detected in a teal from China
(A/teal/China/2978.1/2002(H5N1)) as well as swine from Fujian province
(A/swine/Fujian/F1/2001(H5N1), A/swine/Fujian/F1/2003(H5N1)) isolated in
2001-2003. Russia has not filed an OIE report of the outbreaks in
the Volga Delta / Kalmykia regions, so it is unclear if those isolates
have the REIRRKKR or RERRRKKR cleavage site, but clearly the HPAI
H5N1 in Europe is becoming more diverse.
- This diversity highlights the need for more surveillance
of wild birds in Europe, the Middle East, and Africa because the introduction
of HPAI H5N1 into these regions presents new opportunities for recombination
and the generation of novel genes which may have an increased efficiency
of human-to-human transmission.
- Recent reports from the Ukraine indicated the H5N1 isolated
on the Crimea peninsula was unique and birds died 2-8 hours after symptoms,
which included blindness in waterfowl. These novel isolates also
point toward the need from more sequence data from poultry outbreaks in
China. Novel HA cleavage sites have been reported in whooper swan
isolates from Mongolia as well as a chicken in Hunan, which was linked
to the first reported human H5N1 case in mainland China.
- H5N1 is clearly rapidly evolving in Asia and Europe
and timely reporting of sequence data is increasingly important.
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