They say the H5N1 strain of bird flu currently circulating the globe is not the only cause for concern. A team from the Centres for Disease Control say that the H5N1 strain currently circulating is not the only virus that could potentially trigger a pandemic. The strain, H7, also mainly affect birds - a deadly version of the H7N7 strain hit poultry in the Netherlands in 2003, and a less severe form, H7N2, broke out in the UK last year and in the period 2002 to 2004 several outbreaks of H7N3 and H7N2 have been reported.

Each of these outbreaks have had a minimal affect on humans with only one death and reported incidents of about 80 eye infections and a few mild respiratory infections.

An analysis of a case in 2003 in New York has shown that the H7N2 virus has the unusual capability of replicating in the respiratory tract of mammals which indicates that it could possibly be transmissible from person to person.

An animal study also revealed that this particular H7N2 strain could be passed from animal to animal which suggests that the virus could be acquiring an ability to bind to sugars found on the cells of the human windpipe which has happened before in all three of the 20th-century flu pandemics.

The scientists say the findings suggest that the H7 class of viruses have begun to adapt and recognise the receptors that are preferred by the human influenza virus and this is why continued surveillance and research into these viruses is imperative.

[28 May 2008 14:55]

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