Don't Ask Don't Tell H5N1 Surveillance in Japan
Recombinomics Commentary 10:24
April 29, 2008
A Japanese national institute of animal health confirmed Tuesday that the H5 strain of the bird flu virus detected in several dead and dying swans in northeastern Akita Prefecture last week belongs to the highly virulent H5N1 strain.
Three dead swans and one dying swan were found on Monday last week near Lake Towada, with the virus being detected in three of them. Another dead swan and two dying swans were later found on the shores of the lake from Wednesday to Saturday.
The above comments confirm H5N1 in dead or dying swans in Japan. The confirmation was not a surprise (see satellite map). In three of the last five seasons South Korea has reported H5N1 on farms and each season H5N1 was subsequently found in Japan. In 2003/2004 the sequences were closely related. Japan hasn’t released sequences from last season, but the sequences will almost certainly be closely related to the sequences from South Korea, which were the Uvs Lake strain of H5N1. It is likely that H5N1 this season will also be closely related to the Uvs Lake strain.
However, this season the H5N1 was detected as wild birds migrate out of South Korea and Japan, instead of the fall / winter when birds are arriving. The detection delay this season raises surveillance issues in both countries. In Japan the H5N1 was detected in the absence of a reported outbreak in domestic poultry. The increased surveillance was in response to the record breaking outbreaks in South Korea. Thus, H5N1 can be circulating undetected when surveillance is at the “normal” level, but is easily detected when surveillance is “enhanced”.
This “don’t ask don’t tell” approach to H5N1 surveillance is widespread. England found H5N1 in wild birds (swans and a Canada goose) when surveillance was “enhanced”, and Switzerland found H5N1 in a asymptomatic pochard in an area of enhanced surveillance.
These examples of H5N1 in wild bird populations in regions where there are no reported outbreaks in domestic poultry provide more evidence for widespread H5N1 in wild bird populations that are only detected under “enhanced surveillance”, which is usually not present, even in countries such as England and Japan. Other countries rely on conservation groups which use collection and testing procedures that are known to produce an over abundance of false negatives.
The latest data in Japan demonstrate that surveillance that is not enhanced is well into the abysmal category, where it has been for many years.
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