More H5N1 Spread in Rostov
Recombinomics Commentary
December 25, 2007
A fifth case of bird flu has been confirmed at a farm in the Rostov Region, south Russia, close to the site of previous outbreaks, the regional emergencies ministry said. "The outbreak at two smallholdings was registered on Saturday, samples were taken and sent for analysis, they came back positive for bird flu," the ministry said.
All 79 birds on the smallholding have been culled. A quarantine zone has been introduced in the Tselinsky district near the site of the first case of the deadly virus.
The first bird flu outbreak was discovered in late November at the Gulyai-Borisovskaya poultry farm in the Rostov Region. The farm's entire population of 500,000 chickens was culled. Later a bird flu outbreak was registered at a smallholding close to the farm.
Another outbreak was then discovered at a farm in the Tselinsky district.
The Rostov Region is particularly vulnerable to bird flu as part of the Krasnodar Territory, which is on a route taken by migrating birds in winter. In September, the region was hit by the H5N1 strain and 230,000 birds were culled.
The above comments describe the continuing spread of H5N1 in Rostov (see satellite map). As noted, this is the fifth outbreak in the past few weeks. In September, there were outbreaks in Krasnodar on a poultry farm. The sequence of an isolate from the farm traced back to the massive outbreak over the summer of 2006 at Uva Lake, the largest lake in Mongolia (see satellite map). The outbreak was on a par with Qinghai Lake a year earlier, but neither Russia nor Mongolia filed OIE reports on the outbreak. However, sequences from wild bird isolates in both countries were published. The sequences were related to earlier isolates in Afghanistan and India as well as isolates from Azerbaijan.
However, the sequences from Krasnodar clearly linked back to the wild bird outbreak at Uva Lake. Similar isolates were described by FLI in Germany when they analyzed sequences from multiple wild bird outbreaks in Germany over the summer. Recently those sequences were released, and as described by FLI, they linked back to Uva Lake and were closely related to the Krasnodar chicken isolate. Recently a sequence from a whooper swan in Krasnodar was released. The HA sequence was identical to the poultry isolate and the sequences for all eight gene segments were 99.95% identical.
H5N1 is also spreading in Germany at this time, and another report from FLI indicated it was also similar to the summer sequences related to Uva Lake. This strain appears to have become dominant. Recently, sequences from the outbreak in late 2006 outbreak in South Korea were released, and they also are closely related to the Uva Lake sequences.
Sequence from other outbreaks this year (Kuwait, Czech Republic, France, England) have not been released, but all have been described as having a close relationship to the Uva Lake strain.
The increased reporting of recent H5N1 outbreaks in Saudi Arabia, Romania, Poland, and the spreading outbreak in Rostov, couple with the bird and human outbreak in Pakistan, suggests reported H5N1 in wild birds, poultry, and people will be on the rise in coming weeks. Recent alerts have been issued in Pakistan, Egypt, and Jordan.
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