Subject: 廈村雞場禽流感報告 Epidemiology Report of H5N1 in Ha Tsuen [Print This Page] Author: HKBWS WY Time: 8/04/2009 16:38 Subject: 廈村雞場禽流感報告 Epidemiology Report of H5N1 in Ha Tsuen
2008年12月新界廈村一家雞場爆發H5N1型高致病性禽流感流行病學報告
Epidemiology Report of the Highly Pathogenic Avian Influenza H5N1 Outbreak in December 2008 in a Chicken Farm in Ha Tsuen, New Territories
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調查組的結論如下：
(1) 病毒如何傳入雞場
(i) 由於雞場及其附近有水禽及其他禽類出沒，而雞場中的樹木和露天滲水池容易招引野鳥，包括大型水禽（鷺及白鷺），所以病毒可能是透過受感染野鳥的糞便傳入雞場。雖然受感染的17號禽舍有防鳥網覆蓋，但該禽舍入口附近的一段通道位於有橫枝伸展的樹木下。該禽舍的設計可能會使野鳥糞便污染禽舍內的露天區域。
(ii) 2008年12月4日至6日從北方及東北方吹來的强風及陣風，或會將樹木上可能受污染的灰塵及樹葉從鄰近17號禽舍的北門吹入該禽舍。污染物可能在禽舍一角聚集，而該處也是初步出現較高家禽死亡率的地方。
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The Investigation Group’s conclusions are as follows:
(1) Introduction of virus into farm
(i) The virus could have been introduced to the farm by droppings of infected wild birds given the presence of aquatic birds and other birds on and around the farm and the presence of trees on the farm and uncovered soak away pits that are attractive to birds, including large aquatic species (herons and egrets). Part of the aisle of the infected shed no. 17, although covered by bird protection nets, was under some branches of the trees near its entrance. This design of the shed could have allowed the droppings of wild birds to contaminate the exposed area inside the shed.
(ii) The strong winds and gust from the north and north-east from 4 to 6 December 2008 could have deposited potentially contaminated dust and leaves from the trees into the nearby shed no. 17 via its north opening. These contaminated materials could then have gathered at the corner of the shed where the initial high mortality in poultry occurred.
...... 完整報告請按 Please click for full reportAuthor: ajohn Time: 9/04/2009 11:09
I'm very surprised that the HKBWS should have picked out the statements suggesting this infection was from wild birds. This is similar to the scare tactics often used by the global (and HK) media that wild birds are responsible for spreading the infection across the world. This gives a misleading view of the contents of this report - I recommend that people read the report if they are interested in the actual conclusions.
Findings of the investigation include:
The source of infection is not proven. See section 6.4 of the report: "There are a number of possible routes of introduction of infection, including wild birds and the entry of items or people from outside the farm, coupled with or facilitated by biosecurity lapses". Wild birds may be a source, but the findings also suggest that biosecurity measures were not always applied, and there remains the possibility of infection from other sources (eg visitors to the site who have not been properly disinfected).
Genetic testing of the virus show that it is unrelated to most recent cases in wild birds in Hong Kong. The closest strains genetically involved a peregrine in March 2008 and a poultry market in June 2008, although these were not directly linked to the Ha Tsuen infection.
Birds (eg sparrows) may have been involved with the immediate spread of H5N1 within the farm, as they had access into the sheds. This is not the same as these wild birds being the source of the infection onto the farm.
I think the report is actually fairly balanced and does not jump to conclusions about the infection. The summary given in the previous post, however, does imply that wild birds are to blame.
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