May 24, 2006 -- What is the avian flu?
It is a flu virus that originated in Asian birds at some unknown point. All flu viruses have two major components, an H component and an N component. This virus is H5N1. It lives harmlessly in ducks but is highly lethal in some other birds, including chickens.
Since 1997, over 120 million birds have died of the flu or been destroyed in an effort to stop the spread.
H5N1 is also highly lethal in humans, who can contract it by handling infected birds.
When did the avian flu spread to humans?
In 1997, 18 humans were infected with H5N1 flu. Six patients died. The virus subsided but did not go away. In 2003-2004, new outbreaks in both birds and humans occurred. By the end of 2004, Asia had reported 44 cases, 32 of which were fatal.
According to the World Health Organization, in 2006 so far, there have been 74 cases and 48 deaths. The grand total since 2003 is 218 cases with 124 deaths.
Has it been found in other animals besides birds?
Yes, it has been found in tigers, pigs and domestic cats. This is a concern because H5N1 could mix with another flu in these animals and mutate into a form that is more easily transmissible to humans.
Has the H5N1 virus been detected in North American birds?
As of spring 2006, there have been no cases detected in commercial birds, wild birds or humans in North America.
Why is there so much concern over H5N1?
H5N1 has a high degree of lethality. If the virus in animals mutates to a form that is easily transmissible to humans, it could quickly kill millions of people worldwide.
Have there been cases of human-to-human transmission?
Yes, there was at least one case, perhaps two, in Asia, of human-to-human transmission of H5N1 influenza reported in 2005. But the virus is not yet in a form that will transmit easily between humans.
Is it inevitable that H5N1 will mutate into a pandemic form?
No. It remains a very real possibility, and there is no way to tell for sure when, or even if, it will happen. Some experts believe that since it has been many years now without the virus mutating much, the threat of easy human-to-human transmission is diminished. But it is still possible.
History has told us that some form of flu epidemic is nearly certain in our future. But which virus it is -- H5N1 or some other virus -- remains unclear, and the exact timing of the epidemic is impossible to predict.
Is there any treatment for H5N1 flu?
There is no guaranteed cure. Currently, patients are quarantined and a variety of treatments are used to manage the respiratory symptoms and fever. There has been some anecdotal evidence that the antiviral medicine oseltamivir (Tamiflu) can reduce symptoms in infected patients, but treatment must be administered early. In a 2004 report of 5 patients treated several days after infection with Tamiflu, 4 of the patients died.
Tamiflu has only been scientifically evaluated in mice. A study from July of 2005 finds that, when given Tamiflu for 8 days, 80% of mice survived. Only 50% of mice treated for 5 days survived, suggesting that longer treatment may be more beneficial.
There have been no studies on Tamiflu's effectiveness against H5N1 in humans.
Does Tamiflu prevent infection of H5N1?
No. Tamiflu won't keep the virus from infecting a person. It works by minimizing the spread of the virus within the body, thereby reducing the severity and duration of symptoms.
Is Tamiflu approved by the FDA to treat H5N1?
Tamiflu is approved to treat influenza A and influenza B type viruses. H5N1 is an A-type virus, so Tamiflu is an appropriate potential treatment per the FDA. However, Tamiflu was FDA approved based on its ability to treat other types of A viruses, not H5N1. Tamiflu's effectiveness in humans with H5N1 has never been tested.
Are there any other treatments effective against H5N1?
Animal and lab studies suggest that Relenza, which is in the same class of drugs as Tamiflu, may also be effective against H5N1. A third antiviral medication, RWJ-270201, has also been shown in lab studies to be effective against H5N1.
Why are governments stockpiling Tamiflu?
Despite the uncertainty, Tamiflu is the most effective treatment we have right now. It may also offer some protection against other potential pandemic flus. Currently, the Infectious Disease Society of America recommends that the U.S. stockpile enough antiviral treatment to treat at least 50 percent of the population. The World Health Organization believes a better number would be 80 percent.
What about creating a vaccine against avian flu?
Scientists are working on a vaccine, but creating an effective vaccine is difficult. To spread to a pandemic type of flu, the H5N1 virus that is infecting people now would have to mutate. Once it mutates, any vaccine created specifically for H5N1 may no longer be effective. So creating a vaccine based on the current H5N1 strain is of limited use.
Also, vaccines take several months to create. Once an outbreak occurs, a vaccine may not be created in time to be of use.
What other steps should governments be taking to prepare for a flu pandemic?
The major important thing is for governments to have a plan. Having a stockpile of antiviral medication is useless unless there is a way to distribute the drugs to people who need them. Surveillance is also highly critical; if we can catch a flu pandemic early, there is a better chance at stopping it or lessening its severity. Governments need to have an alert plan. They need a way to communicate quickly and effectively to hospitals, doctors and the general public what do to in the event of a dangerous flu outbreak.