H5N1 Common Source in Aswan Egypt
Recombinomics Commentary
March 21, 2007
The two most recent confirmed H5N1 cases in Egypt are from the Aswan Goveronate. One patient (10F) was admitted March 13 with symptoms. The most recent confirmed case (2M) was admitted three days later with symptoms which developed on March 15. Although the latest WHO update indicated the epidemiological data failed to link the two cases, the sequences from the 10F, A/Egypt/2321-NAMRU3, and 2M, A/Egypt/2331-NAMRU-3, have identical NA sequences and the HA sequences differ by a single nucleotide.
The two sequences from Aswan are readily distinguished from earlier human and poultry isolates from Egypt. Although all isolates are the Qinghai strain (Clade 2.2) of H5N1 and have multiple regional markers clearly identifying the Egyptian origin of the isolates, the Aswan isolates have evidence for both reassortment and recombination. The NA sequences are similar to earlier NA sequences from Beni Suef and Fayyoum. However, the HA sequences have a novel cleavage site that matches the cleavage site reported in whooper swans in Mongolia in 2005. Although other isolates, including those from the Gharbiya cluster, link back to Mongolia, none of the prior isolates have the novel Mongolian cleavage site.
The virtual identity in the sequences from the patients in Aswan indicate they were infected by a common source. More information on the epidemiology would be useful. The infection of two children in Aswan who were hospitalized three days apart is cause for concern, although the sequences lack M230I, and the presentations thus far indicate a mild course.
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