A death of a man from bird flu in Vietnam´s Northern Province, has brought the total deaths in the country since late 2003 to 38.

The 46-year-old man died three days after he entered the Institute of Tropical Diseases in Hanoi capital, where two other bird flu patients were receiving treatment.

The regional death toll in Southeast Asia stands at 53. The World Health Organization (WHO) warns of a possible epidemic if the disease changes into a virus that can spread person to person, and local health agencies and the WHO report that to date there is no positive evidence for human-to-human transmission of bird flu virus strain H5N1 in Vietnam.

Influenza A (H5N1) virus, is an influenza A virus subtype that occurs mainly in birds and it was first isolated from birds in South Africa in 1961. Like all bird flu viruses, H5N1 virus circulates among birds worldwide, is very contagious among birds, and can be deadly.

Outbreaks of influenza H5N1 were reported among poultry in eight countries in Asia, Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam, during late 2003 and early 2004. More than 100 million birds in the affected countries either died from the disease or were killed in order to try to control the outbreak and by March 2004, the outbreak was reported to be under control.

By late June 2004, however, new deadly outbreaks of influenza H5N1 among poultry were reported by several countries in Asia, in Cambodia, China, Indonesia, Malaysia [first-time reports], Thailand, and Vietnam. Health officials believe that these outbreaks are ongoing. Human infections of influenza A (H5N1) have been reported in Thailand, Vietnam and Cambodia.

Although the H5N1 virus does not usually infect humans, in 1997, however, the first case of infection from a bird to a human was seen during an outbreak of bird flu in poultry in Hong Kong. During that outbreak the virus caused severe respiratory illness in 18 people, 6 of whom died.

Since then there have been other cases of H5N1 infection among humans with the most recent cases occurring in Thailand, Vietnam and Cambodia during large H5N1 outbreaks in poultry. The death rate for these reported cases has been about 70 percent. Most of these cases occurred from contact with infected poultry or contaminated surfaces; however, it is thought that a few cases of human-to-human spread of H5N1 have occurred.

To date, the spread of H5N1 virus from person to person has been rare and spread has not continued beyond one person, but because all influenza viruses have the ability to change, scientists are concerned that the H5N1 virus could one day be able to infect humans and spread easily from one person to another.

Because these viruses do not commonly infect humans, there is little or no immune protection against them in the human population. If the H5N1 virus were able to infect people and spread easily from person to person, an influenza pandemic could begin.

No one can predict when a pandemic might occur. However, experts from around the world are watching the H5N1 situation in Asia very closely and are preparing for the possibility that the virus may begin to spread more easily and widely from person to person.

The current H5N1 virus outbreak appears to be 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, though studies still need to be done to prove that they work.

There is at present no vaccine to protect humans against the H5N1 virus that is being seen in Asia. However, vaccine development efforts are under way and research studies to test a vaccine to protect humans against H5N1 virus began in April 2005. Researchers are also working on a vaccine against H9N2, another bird flu virus subtype.

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 travellers returning from affected countries in Asia could be infected. Since February 2004, medical and public health personnel have been closely monitoring the situation.