The U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have not recommended that the general public avoid travel to any of the countries affected by H5N1. The following information is intended to clarify the threat posed to humans by avian flu (H5N1) in Asia.
EAP has been closely monitoring avian flu since February 2003.
Avian influenza viruses do not normally infect species other than birds and pigs. The first documented infection of humans with H5N1 happened in Hong Kong in 1997 but did not appear again until early 2003. Then, toward the end of 2003, H5N1 suddenly became highly and widely visible.
Outbreaks of H5N1 virus in poultry and wild birds have caused widespread public concern due to fears that a pandemic may happen as widely reported by the media.
Part of the concern is the mistaken assumption that the geographical spread of the H5N1 virus in bird populations signals the start of an influenza pandemic. All countries are working actively to clarify that the spread of avian influenza in birds does not constitute an influenza pandemic in humans.
Even though, in some few cases, limited human-to-human transmission within the family cannot be ruled out the majority of confirmed human Avian Flu cases were in direct and close contact with infected poultry, their blood or surfaces and objects contaminated by their feces or saliva. Exposure is considered most likely during slaughter, de-feathering, butchering, and preparation of poultry for cooking. There is no evidence that properly cooked poultry or eggs can be a source of infection.
Compared to the large number of birds affected, only a small number of human cases have occurred. It is not presently understood why some people, and not others, become infected following similar exposures.
Suspicions that sustained human-to-human transmission may have taken place will occur when cases are observed that happen close together in time and place among persons, such as family members or health care workers, known to have had close contact with an infected person. These clusters have been detected on some occasions during the 2004 outbreaks. All such instances involved family members. To date, no H5N1 cases have been detected in health care workers despite many instances of close, unprotected contact with severely ill patients.
The most vulnerable population has turned out to be rural subsistence farmers and their families, and these people constitute the true risk group.
There currently is no commercially available vaccine to protect humans against H5N1 virus that is being seen in Asia and Europe. However, vaccine development efforts are taking place. The seasonal flu vaccine does not protect people from the deadly H5N1 virus, but health experts hope that fewer flu cases would reduce the chance of human flu mixing with H5N1 to produce a pandemic strain.
WHO works closely with ministries of health and various public health organizations, which include CDC, to support surveillance.
Out of the six preparedness phases described by WHO, we are now in phase three. Phase six is full pandemic. In phase three a virus new to humans is causing infections, but that virus does not spread easily among humans.
Countries around the world have been developing plans on how to deal with an outbreak of bird flu and the possibility of it spreading between humans. A global meeting opened today in Geneva to develop a common approach on avian influenza and a possible human pandemic influenza.
Travelers to areas affected by avian influenza in birds are not considered to be at elevated risk of infection unless direct and un-protected exposure to infected birds (including feathers, faeces and under-cooked meat and egg products) occurs.
WHO and CDC continue to recommend that travelers to affected areas should avoid contact with live animal markets and poultry farms, and any free-ranging or caged poultry. Large amounts of the virus are known to be excreted in the droppings from infected birds.
