With bird flu outbreaks now confirmed as far west as Turkey and suspected in Romania, the United Nations health agency has called on countries located along migratory routes to be vigilant for signs of disease in wild and domestic birds as it seeks to prevent a human pandemic that could kill millions of people worldwide.

But while the spread of the current H5N1 virus from South-East Asia, where it erupted almost two years ago, to new areas is of concern as it increases opportunities for further human cases to occur, the World Health Organization stressed that all evidence to date indicates that it does not spread easily from birds to infect humans.

In its latest update on the disease, the agency kept its level of pandemic alert at phase 3, meaning that a virus new to humans is causing infections, but does not spread easily from one person to another.

Ever since the first human case of bird flu, linked to widespread poultry outbreaks in Viet Nam and Thailand, was reported in January last year, UN health officials have warned that the H5N1 virus could evolve into a global influenza pandemic if it mutates into a form which could transmit easily between people.

The so-called Spanish flu pandemic of 1918-1920 is estimated to have killed from 20 million to 40 million people worldwide. Overall, there have been more than 110 reported human H5N1 cases, about 60 of them fatal, all in South-East Asia. Some 140 million domestic birds have died or been culled in an effort to curb the spread, WHO said in its release.

In the update, WHO advised countries experiencing outbreaks in poultry to follow certain precautions, particularly during culling operations, and to monitor persons with a possible exposure history for fever or respiratory symptoms. Early symptoms mimic those of many other common respiratory illnesses, meaning that false alarms are likely.

It repeated recommendations that travellers to areas experiencing outbreaks of H5N1 in poultry avoid contact with live animal markets and poultry farms and that people in affected countries avoid contact with dead migratory or wild birds showing signs of disease.

Direct contact with infected poultry, or surfaces and objects contaminated by their droppings, is considered the main route of human infection. Exposure risk is considered highest during slaughter, de-feathering, butchering, and preparation of poultry for cooking. There is no evidence that properly cooked poultry or poultry products can be a source of infection, the release added.