SCIENTISTS FIND MUTATIONS THAT LET BIRD FLU ADAPT TO HUMANS
By comparing influenza viruses found in birds with those of the avian virus that have also infected human hosts, researchers have identified key genetic changes required for pandemic strains of bird flu. The new work, reported in the Nov. 16 issue of the journal Nature, illustrates the genetic changes required for the H5N1 avian influenza virus to adapt to easily recognize the receptors that are the gateway to human cells.
Circumstantial evidence links Spanish flu and encephalitis lethargica, or sleeping sickness Both pandemics were globally distributed and closely related in time. Local, regional, and national epidemics of Spanish flu preceded "similar sized" outbreaks of encephalitis lethargica. Deaths were greatest in the 20- to 40-year age groups for Spanish flu and in the 20- to 50-years for sleeping sickness. A large number of victims of encephalitis lethargica had had influenza in 1918.
The World Health Organisation has urged Chinese and foreign scientists to stop squabbling and share information to figure out how to combat a new H5N1 bird flu virus strain that is spreading unchecked in poultry flocks. Chinese officials and scientists rejected a paper published last week by Hong Kong and U.S. scientists who said a new vaccine-resistant "Fujian-like" H5N1 strain had emerged in poultry in China and may spread across Asia and Europe. In an interview with Chinese media published on Tuesday, two Chinese scientists fired strongly worded rebuttals, saying there was "no scientific basis" for the views and conclusions in the paper. They accused the foreign researchers of "unscientific methods" and said China's vaccination programme was effective. H5N1 remains a disease in birds although it has killed over 150 people since late 2003. However, experts fear it could start a pandemic and kill millions if it ever learns to transmit efficiently among people. Research so far into the Fujian strain shows it poses no heightened danger to people.
Scientists have discovered a new strain of bird flu that appears to sidestep current vaccines. It's infecting people as well as poultry in Asia, and some researchers fear its evolution may have been steered by the vaccination programs designed to protect poultry from earlier types of the H5N1 flu. The discovery by Yi Guan of the University of Hong Kong and colleagues is reported in Tuesday's issue of Proceedings of the National Academy of Sciences. The new variant has become the primary version of the bird flu in several provinces of China and has spread to Hong Kong, Laos, Malaysia and Thailand, the researchers report. It is being called H5N1 Fujian-like, to distinguish it from earlier Hong Kong and Vietnam variants.
The Ho Chi Minh Pasteur Institute has decoded 24 samples of the H5N1 strain of avian influenza, taken from both birds and humans. The results indicate a number of different mutations in the virus.
"The H5N1 type that infected people and waterfowl in early 2005 has several mutations focusing in the important functional parts of the surface proteins. There has been a mutation allowing the virus to breed effectively on mammal tissue and become highly virulent." - Report published on the Institute's Web site.
And in Taiwan, another strain of avian influenza, H7N3, has been found, which is highly pathogenic and able to infect humans.
H5 and H7 are the only avian influenza subtypes known to be found in highly pathogenic outbreaks of the disease.