Indonesian Agriculture Ministry officials take blood sample from an Australian pelican at Gembira Loka Zoo in Yogyakarta, Indonesia, Tuesday, Sept. 20, 2005.

The World Health Organizations' avian flu coordinator says the agency is concerned about the spread of a deadly strain of avian flu and watching for human-to-human transmission of the virus. But the WHO envoy says people should not be fearful. 

David Nabarro, the WHO's avian flu envoy, says the world is overdue for a deadly influenza pandemic, which tends to occur ever 30-to-40 years.

So far, the H5N1 virus has only spread rapidly among birds, and most human infections have been among people who came into direct contact with poultry. The virus, which is known to have infected a little over a hundred people, has killed about half of them.

Officials worry about what could happen if the virus mutates and spreads rapidly through the human population. So far, no effective vaccines have been developed to protect against H5N1, and it is not certain anti-viral drugs would work.

But in an interview on CNN's Late Edition, Dr. Nabarro says no one should panic.

"I would like people not to be a state of deep fear about it, because we do have the possibility of controlling the pandemic and making certain, when it does arrive, we can keep it to having the least possible impact on human society and lives," Dr. Nabarro says.

Last week, representatives from more than 80 nations met in Washington and pledged their cooperation in dealing with an avian flu pandemic.

Dr. Nabarro says he was struck by the willingness of all nations to cooperate. But Dr. Nabarro says maintaining open cooperation will require vigilance.

" It will be difficult to sustain that spirit of openness because there are, of course, big worries about what a pandemic might do for a country's tourism, economy and its internal security. But, again, the work I've got ahead of me is to encourage all countries to be open and transparent," Dr. Nabarro says.

Meanwhile, the first cases of bird flu have been reported in Romania and Turkey. There are a number of different avian flu strains, and officials were awaiting the results of tests to confirm whether it was H5N1.

As a precaution, chickens and turkeys are being slaughtered, and quarantines enforced in town and villages where infected birds were found.