( CNN ) -- Two teams of scientists say they have found a key area of the H5N1 bird flu virus which seems to be vital to its ability to copy itself , and hope the discovery could lead to new drugs to fight the infection . Human-to-human transmission of avian flu is rare , but in some cases , the virus has passed from poultry to humans . The discovery is generating excitement among scientists who are looking for a new weapon against the bird flu virus that typically kills more than half its human victims . Two separate groups of scientists -- one in China , one in France -- used a highly technical process to identify protein that seems to be involved in its ability to replicate itself . That gives researchers a new target , as they try and develop new medications . The announcements , detailed in the British-based journal Nature , come at an uneasy time for those who follow the bird flu strain called H5N1 . So far this disease is mainly affecting birds in some countries and the number of human cases remains small , but the virus has shown no sign of growing milder since it first infected people back in 1997 . It continues to decimate bird flocks in sporadic outbreaks , mostly in Asia , and occasionally breaks into the human population . China 's Ministry of Health reported eight human cases last month , including four deaths . Since 2003 , the World Health Organization has confirmed 404 human cases worldwide . Nearly two-thirds of the victims have died . While H5N1 does n't make headlines the way it did in 2005 , health officials say the continuing severity of the infections means the alarm is still on . Influenza viruses , in general , spread easily . If H5N1 were to acquire the genetic ability to pass easily from person to person , it could turn into a major catastrophe . Many countries have stockpiled both vaccines and antiviral medications , for such a scenario . The same medications that are used to treat regular flu , oseltamivir ( Tamiful ) and zanamivir ( Relenza ) , also seem to be effective against H5N1 . But that 's no reason to rest easy . All flu viruses tend to mutate rapidly , which is why the flu vaccine one year , wo n't protect you against the next year 's flu . Those rapid mutations mean the virus tends to develop a resistance to any widely used medication . Dr. Anthony Fauci , Director of the U.S. National Institute of Allergy and Infectious Disease , told CNN , `` It always happens that eventually , sooner or later , the [ flu ] virus will develop varying degrees of resistance . You just hope that it 's kept to a minimum . '' The findings in Nature may lead to another option to fight bird flu , but an actual new drug is years away . A vaccine could be effective , but they first have to know what strain of flu they 're fighting . The current strategy of health officials around the world is to try to contain isolated cases before they spread . The best case scenario would be , that this H5N1 killer remains primarily a disease for the birds .
Experts say they have found key component of the H5N1 bird flu virus . It is hoped this will lead to better medication to fight the infection . China reported its first human-to-human infection in 2005 . Since 2003 , the World Health Organization has confirmed 404 human cases .