(email received 31 March 2005)Did you see the BBC documentary on TV last night?
There was a unanimous opinion amongst the international experts that the threat of a human epidemic is real and imminent as a result of three epidemiological reflections of changes in this virus over the past 8 years:
1. Increasing geographic spread of outbreaks
2. Endemic (enzootic) establishment of the virus in both domestic and wild bird populations
3. Widening host range (pigs, cats, ferrets, humans etc)
These trends are in themselves foreboding enough, especially when the virulence of this H5N1 virus strain for humans appears to be so far undiminished at 50-70%, but the final factor which seals the inevitability of future genetic mutation and spread of the H5N1 virus are the lifestyle factors and poverty in many of the currently affected countries in S.E. Asia. The programme showed overcrowded and closely intermingled populations of people, chickens, ducks and pigs. Also shown were people eating raw duck's blood (a gastronomic delicacy in some regions!) and live animal and bird markets with livestock overcrowded and stressed.
Our own (http://www.sunflower-health.com) correspondent in Hong Kong reports that live birds are again being sold in markets, despite the temporary ban implemented following the human deaths there in the 1990s. Live birds are also being imported into Hong Kong from southern China. A local expert on the BBC programme predicted that a more human-adapted mutated strain of influenza could spread around the world within two weeks.
The experts interviewed did not place any faith in current public health (slaughter and movement controls) measures to control the H5N1 virus. Vaccination of the human population offered some hope, though limited because of the restricted availability of vaccine stocks, especially in the countries most at risk of a human epidemic starting. The impossibility of predicting the exact antigenic genetic form of a more human-adapted mutant also made vaccine stocks a hit-or-miss or "low protection" proposition.
Current research programs into the Bird 'flu problem are working on improved vaccine development. A research project was shown which is combining H5N1 with human influenza strains under laboratory conditions in order to predict the form and behavior that a recombination virus (potentially resulting from dual infection of a person or pig with a common human and an avian influenza strain) might take. More info about H5N1 HPAI in poultry, humans and swine at http://www.pighealth.com/influenza2.htm