H5N1 virus does not usually infect people, but more than 200 human cases have been reported. Most of these cases have occurred from direct or close contact with infected poultry or contaminated surfaces; however, a few cases of human-to-human spread of H5N1 virus have occurred. So far, spread of H5N1 virus from person to person has been rare and has not continued beyond one person.

Humans can become infected with avian influenza from direct or close contact with infected poultry or surfaces contaminated with secretions and excretions from infected wild birds or domestic poultry. Because all influenza viruses have the ability to change, scientists are concerned that HPAI virus one day could be able to infect humans and spread easily from one person to another, in which case the pandemic threat will be inevitable.

New human flu viruses can arise from bird flu viruses that then change to a form that can infect humans and spread readily from person to person. Current bird flu outbreaks in Asia, Europe and Africa are caused by a type of flu virus called "H5N1." Human infections and deaths due to the H5N1 virus have occurred, although the virus has at this time not developed the ability to pass easily from person to person and cause outbreaks in humans.

About one in five people infected by the virus develop West Nile fever, a typically mild illness that causes fever, muscle aches, fatigue, headache and joint pain. These persons recover fully and do not require hospital care. A smaller number of infected persons, 1%, develop encephalitis or meningitis with symptoms of high fever, neck stiffness, confusion, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis.

The H5N1 virus does not usually infect humans. In 1997. However, the first case of spread from a bird to a human was seen during an outbreak of bird flu in poultry in Hong Kong, Special Administrative Region. The virus caused severe respiratory illness in 18 people, 6 of whom died. Since that time, there have been other cases of H5N1 infection among humans.

The H5N1 virus currently infecting birds in Asia that has caused human illness and death is resistant to amantadine and rimantadine, two antiviral medications commonly used for influenza. Two other antiviral medications, oseltamavir and zanamavir, would probably work to treat flu caused by the H5N1 virus, but additional studies still need to be done to prove their effectiveness.

There currently is no commercially available vaccine to protect humans against the H5N1 virus that is being seen in Asia and Europe. However, vaccine development efforts are taking place. Research studies to test a vaccine to protect humans against H5N1 virus began in April 2005, and a series of clinical trials is underway. For more information about the H5N1 vaccine development process, visit the National Institutes of Health website.

No. Currently available vaccines will not protect against disease caused by the A(H5N1) strain in humans. The WHO and many other organisations worldwide are working towards producing a vaccine against avian A(H5N1) influenza. Candidate vaccines have been produced, which are being evaluated in humans. However mass production of a vaccine will probably not take place unless there is evidence of efficient spread between humans.

Although it is unpredictable when the next pandemic will occur and what strain may cause it, the continued and expanded spread of a highly pathogenic—and now endemic—avian H5N1 virus across eastern Asia and other countries represents a significant threat. Avian H5N1 influenza infection in humans was first recognized in 1997 when this virus infected 18 people in Hong Kong, causing 6 deaths.

In February 2004, CDC provided U.S. health departments with recommendations for enhanced surveillance (“detection”) in the U.S. of avian influenza A (H5N1). Follow-up messages, distributed via the Health Alert Network, were sent to the health departments on August 12, 2004, and February 4, 2005; both alerts reminded health departments about how to detect (domestic surveillance), diagnose, and prevent the spread of avian influenza A (H5N1).

Scientists cannot say that there will definitely be an outbreak in the United States, although most believe that it will happen. It is not possible to predict an exact date. Scientists have identified a number of events that they would expect to see as we approach an outbreak and they have already observed many of them. Therefore, it is wise to start preparing now.

The U.S. Centers for Disease Control (CDC) currently advises travelers to countries with known outbreaks of avian influenza A of the H5N1 strain to avoid poultry farms, contact with animals in live food markets, and any surfaces that appear to be contaminated with feces from poultry or other animals. Human cases of avian influenza infection have been reported in several countries, including Azerbaijan, Cambodia, China, Egypt, Indonesia, Iraq, Thailand, Turkey and Vietnam.

To date, the high pathogenic H5N1 strain of the avian flu virus has resulted in the deaths of millions of domestic birds. Despite the millions of people who have had close contact with domestic fowl during the past 10 years in Asia, just over 325 people have been infected worldwide. This is an extremely low rate of infection. However, human health officials are concerned with the greater than 50 percent mortality rate of people that have been infected.

The current risk to Americans from the H5N1 bird flu outbreak in Asia is low. The strain of H5N1 virus found in Asia and Europe has not been found in the United States. There have been no human cases of H5N1 flu in the United States. It is possible that travelers returning from affected countries in Asia could be infected if they were exposed to the virus. Since February 2004, medical and public health personnel have been watching closely to find any such cases.

To date, the high pathogenic Asian H5N1 strain of the avian flu virus has resulted in the deaths of millions of domestic birds. Despite the millions of people who have had close contact with domestic fowl during the past nine years in Asia, more than 320 people have been infected worldwide. This is an extremely low rate of infection. However, human health officials are concerned with the 61 percent mortality rate of people that have been infected.

The H5N1 virus does not usually infect humans. In 1997, however, the first case of spread from a bird to a human was seen during an outbreak of bird flu in poultry in Hong Kong. The virus caused severe respiratory illness in 18 people, 6 of whom died. Since that time, there have been other cases of H5N1 infection among humans. Most recently, human cases of H5N1 infection have occurred in Thailand, Vietnam and Cambodia during large H5N1 outbreaks in poultry.

Viruses usually can infect more than one type of cell. Thus, when viral vectors are used to carry genes into the body, they might alter more than the intended cells. Also, whenever a gene is added to DNA, there is the danger that the new gene could be inserted in the wrong place, possibly causing cancer or other damage.

The current risk to Americans from the H5N1 bird flu outbreak in Asia is low. The strain of H5N1 virus found in Asia has not been found in the United States. There have been no human cases of H5N1 flu in the United States. It is possible that travelers returning from affected countries in Asia could be infected. Since February 2004, medical and public health personnel have been watching closely to find any such cases.

In February 2004, CDC provided U.S. health departments with recommendations for enhanced surveillance ("detection") in the U.S. of avian influenza A (H5N1). Follow-up messages (Health Alert Network) were sent to the health departments on August 12, 2004, and February 4, 2005, both reminding health departments about how to detect (domestic surveillance), diagnose, and prevent the spread of avian influenza A (H5N1). It also recommended measures for laboratory testing for H5N1 virus.

Humans have caught H5N1 mainly through very close and prolonged contact with poultry in places such as markets and poultry farms, where there is a high density of different species of bird mixing, and where they are exposed to both live and dead birds and their droppings. There is little risk of people in New Zealand being infected through normal contact with birds. New Zealand does not have live bird markets and our commercial poultry industry operates under strict biosecurity measures.

No. Currently available vaccines will not protect against disease caused by the H5N1 strain in humans. WHO is urgently working together with laboratories in the WHO Global Influenza Surveillance Network to develop a prototype H5N1 virus for use by leading vaccine manufacturers. available vaccine prototype virus, developed using the 2003 strain of H5N1 (which caused the two human cases in Hong Kong), cannot be used to expedite vaccine development.