Leading avian influenza scientists from around the world say more research is needed to understand the H5N1 bird flu virus to be able to effectively diagnose and treat the disease. That's the conclusion of scientists attending a two-day World Health Organization (WHO) meeting to review what steps need to be taken to prevent the virus from becoming easily transmissible among humans.
The avian flu experts agree, better diagnostic tests must be developed to identify those people who are carrying the H5N1 virus, but do not show symptoms. They note the virus is not stable and keeps changing its form.
The head of WHO's Animal and Human Influenza Program, Mike Perdue, says the same is true for anti-viral drugs. He says hospital and clinical studies have discovered some resistance to the two primary anti-viral drugs used to treat human cases of the deadly H5N1 strain of bird flu. These are Tamiflu and Amantadine.
"So, there is an urgent need to look at other anti-viral avenues, either different ways of delivering current drugs, or new variations on the drugs that are available," said Perdue.
In most cases, Perdue says, Tamiflu continues to save lives, but he notes the drug must be used very early in the infection to be effective.
Bird flu is taking a huge economic toll. Some 230 million birds have been destroyed to prevent the disease from spreading among poultry, and to limit human exposure. In the first 18 months of the pandemic, between 2003 and 2004, WHO reports, the global agriculture sector lost more than $10 billion. Those most affected are small farmers, who have had their livelihoods wiped out.
Purdue says the virus has not been seen in migratory birds for many months, and it is not clear whether it will reappear this year. He attributes this to heightened surveillance in countries where bird flu has surfaced.
"So, they have started looking closer at their poultry production practices relative to the migratory bird flight patterns," he added. "We have also had more interest in the illegal trade of poultry and poultry products, which some people say is also a significant mechanism for transmitting the virus. So, it is just this heightened awareness of the fact that the virus is being spread by unique vectors or transmission routes, I think, has increased the likelihood that they will keep it out of the poultry population."
For now, avian influenza is still a disease of animals. Only people who have had close contact with poultry infected with the deadly H5N1 strain of the virus have become ill and died. Scientists say if they can solve the problem in animals, they can solve it in humans. To date, the World Health Organization reports 251 human cases of bird flu, among whom 147 have died.