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H5N1 Surveillance Concerns in Japan and Alaska
Recombinomics Commentary 22:24
May 2, 2008
The detection of H5N1 in southeastern Russia and northeastern Japan has raised concerns of H5N1 migration into new regions. In the past H5N1 in central or eastern Russia was limited to southern Siberia near Chany Lake in Novosibirsk, or Uvs Lake in Mongolia. Although low path H5 has been detected in southeastern Russia near Lake Khanka in Russia or Xingkai in China, the first confirmed case of H5N1 was reported last month. Similarly, H5N1 in Japan was limited to central and southern regions. The confirmed H5N1 in Akita and suspected H5N1 in Hokkaido represent new areas and raise concerns that H5N1 is expanding its geographical reach into North America via the Aleutian Island (see satellite map).
There have not been any confirmed H5N1 outbreaks in North America, although the circumstances surrounding the H5 PCR positive dead gosling on Prince Edward Island suggest H5N1 may already be circulating in North America, but hasn’t been confirmed. The testing protocols in North American surveillance continue to raise concerns because testing of fecal samples or cloacal swabs is not sensitive, especially for clade 2.2, which is the H5N1 circulating in migratory birds.
The outbreaks in southeastern Russia and northwestern Japan are the closest confirmed H5N1 cases to North America. The case in Hokkaido is approximately 800 miles from the Aleutian Islands, which has focused attention of surveillance in Alaska. The public protocols indicate that testing will involve fecal samples and cloacal swabs, even though these approaches are likely to generate false negatives. Similarly, Japan plans to increase testing of fecal samples to 20-100 per site, which is also unlikely to detect H5N1.
The approaches are curious because the lack of sensitivity is well known. The failure of these approaches to detect H5N1 in live birds near dead and dying H5N1 positive waterfowl raised serious concerns over these approaches, and multiple studies have demonstrated that pharyngeal and throat swabs are more sensitive than cloacal swabs. Since the studies in Alaska include collection of cloacal swabs, the rationale behind not also taking pharyngeal or tracheal swabs is unclear.
Collection of more pharyngeal or tracheal swabs would be useful.
Recombinomics Paper at Nature Precedings