Commentary
H5 Spread to Benin
Recombinomics Commentary 12:47
August 27, 2008
Live chickens purchased at the market in Lokossa as part of the routine surveillance and of the training of managers and other laboratory officials on biomolecular techniques at the Veterinary Laboratory of Parakou.
Causal agent Highly pathogenic avian influenza virus Serotype H5
The above comments from the Benin OIE report describe two chickens that are H5 PCR positive. It is likely that the birds were infected with H5N1 clade 2.2.3 Uvs Lake strain recently reported at multiple locations in northern Nigeria (see satellite map). These outbreaks have a striking parallel with outbreaks in Europe a year earlier.
In June of 2007, a presentation at the Options VI meeting on influenza declared wild birds in Europe to be H5N1 free, based on live bird surveys by various bird conservation groups. These assays, especially when screening fecal samples or cloacal swabs have a notoriously poor record, beginning with testing of wild birds at Erhel Lake in Mongolia in 2005 by these same groups. In the summer of 2005 dead wild birds at the lake were positive for H5N1 clade 2.2, but the testing of live birds at the lake failed to find any H5N1 positives. H5N1 subsequently migrated to the south and west, spreading clade 2.2 into over 50 countries west of China.
Included in this spread were multiple countries throughout Europe, which were H5N1 positive in early 2006. However, the frequency of positives markedly decline in late 2006 and early 2007, which led to the announcement at the talk. However, within minutes of the conclusion of the talk, the Czech Republic reported H5N1 at a poultry farm, which was quickly followed by reports of H5N1 in dead wild birds at multiple locations in Germany, as well as neighboring countries of the Czech Republic and France. The H5N1 was the Uvs Lake strain of clade 2.2.3, which had not been previously reported in Europe. The strain was initially found at Uvs Lake in Mongolia and adjacent locations in Tyva, Russia in the summer of 2006. In the fall of 2006, the strain was found in South Korea and Japan, followed by outbreaks in early 2007 in Kuwait. After the reports of Uvs Lake clade 2.2.3 in the summer of 2007 in Europe, it then became the dominant strain throughout Europe in late 2007 and early 2008.
Last month the Uvs Lake was reported for the first time in Africa, when H5N1 was detected at multiple locations in northern Nigeria. It is likely that the H5 positive poultry in southern Benin is also the Uvs Lake strain of clade 2.2.3.
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