Qinghai H5N1 Confirmed in Ghana
Recombinomics Commentary
May 2, 2007
Sophia Twum-Barimah, a spokeswoman for WHO in Ghana's capital, Accra, said the virus was first detected by a Ghanian lab and then confirmed by an Egyptian research center.
The above comments indicate US NAMRU-3 has confirmed H5N1 in Ghana. This confirmation was not unexpected. Countries neighboring Ghana have had confirmed cases of H5N1 last year and this year, including a human case in Nigeria.
The sequences from the Nigerian case are the only sequences from western Africa this year. The HA sequence had a number of regional polymorphisms from last season. However, the polymorphisms had been previously been localized to other regions, including a number that were in Egyptian isolates in 2006 and 2007.
The added diversity due to recombination in the Nigerian sequence mimicked results in Egypt, raising concerns that the added genetic complexity would lead to an increase in human cases.
The confirmation by NAMRU-3 should generate sequence data on the new isolates, which will provided needed monitoring on the evolution of the Qinghai H5N1 strain found throughout Europe, the Middle East, and Africa.
Monitoring of changes in regions such as Egypt and western Africa are important because migratory bird flyways overlap in these regions. In Egypt, the more recent isolates were more complex and diverse in 2007 when compared to 2006. Moreover, the same polymorphism, NA G743A, was acquired by multiple strains in Egypt, highlighting rapid evolution via recombination.
The overlapping flyways create environments that speed such evolution because of increased frequencies of dual infections.
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