Experts from the World Health Organization are concerned over the new cases of Avian Influenza or the H5N1 in poultries in Egypt, Indonesia, Thailand and Vietnam, saying that the virus may mutate into a new strain if it comes into contact with another influenza virus.

“The presence of H5N1 in poultry poses a health risk in two ways. First, it places those in direct contact with birds — usually rural folk and farm workers — at risk of catching the often fatal disease. Second, the virus could undergo a process of ‘reassortment’ with another influenza virus and produce a completely new strain,” WHO said in a statement.

Reassortment of viruses occurs when the genes of two or more types mix in a host animal such as pig, duck or chicken and form an entirely new strain.

Dr. Shin Young-soo, WHO Regional Director for the Western Pacific, said the H5N1 could combine with the pandemic influenza A (H1N1) and could produce a new virus that is as deadly or as contagious as the A (H1N1).

"We don't know if this is possible, but we are certainly aware of the risk. We are on alert for this development," Shin said.

The WHO official said the A (H1N1) was a result of the reassortment of avian, swine and humans strains of influenza in pigs in Mexico.

As of November 15, A (H1N1) cases in the world have reached 526,060 with 6,770 deaths while around 80 million doses of vaccine have been distributed and some 65 million people vaccinated.

“Influenza viruses are unpredictable,” Shin said. “In areas where A (H1N1) is endemic, we and our partners and national governments are working to build surveillance systems to identify changes in the behavior of the virus. We are also focusing on early response capacity to reduce the potential threats to human health."

Outbreaks of Avian flu have been reported in poultry flocks in 60 countries in Asia, Europe and North Africa since 2003.

It is now considered endemic or naturally occurring in Egypt, Indonesia and Vietnam.

Meanwhile, the Norwegian Institute of Public Health recently reported a mutation detected in three A (H1N1) viruses.

The WHO website reported that the viruses were isolated from the first two fatal cases of A (H1N1) in Norway plus one other virus from a patient with a severe illness.

“Norwegian scientists have analyzed samples from more than 70 patients with clinical illness and no further instances of this mutation have been detected. This finding suggests that the mutation is not widespread in the country,” WHO said, adding that the mutated virus remains responsive to the antiviral drugs Oseltamivir and Zanamivir.