Bird flu has hit 45 countries, killed more than 100 people and seems to be spreading quickly, the U.N. official in charge of tracking the virus said Wednesday.

Dr. David Nabarro said the virus has led to the deaths of some 200 million birds and has impoverished millions of small poultry farmers.

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Between 2003 and 2005 the virus was reported in 15 countries. But in the first four months of this year it has moved rapidly to 30 new countries, with major outbreaks in Turkey, Iraq, Israel, Gaza, Egypt, Afghanistan, Pakistan, Myanmar, India, Nigeria, Niger, Cameroon and Bukina Faso.

"I suspect we're going to see further spread of H5N1 into other countries," he said, referring to the deadly and virulent strain of the virus.

"This is very similar to the virus that caused the influenza pandemic of 1918," Nabarro said. It's not identical but it's similar. ... So therefore, the 1918 virus, which caused this huge pandemic associated with 40 million deaths, seems to have a successor waiting in the wings."

Nabarro, the U.N.'s chief coordinator for avian influenza, spoke at a meeting organized by the United Nations Foundation on how to inform people around the world of the bird flu threat.

He said the H5N1 virus is known to have stricken more than 200 people, but it probably has affected "many, many more."

"And this virus has led to the deaths of 200 million birds — around $20 billion worth of consequences for the countries affected — and this led to the impoverishment of millions of smallholders whose livelihoods depend on poultry," he said.

"The poultry industry is in a terrible state because of drop in demand and also real problems of import and export controls," he added.

Even worse, Nabarro said, the virus has spread to wild birds, including Muscovy ducks and certain kinds of geese that can carry it long distances without any symptoms.

These wild birds are spreading H5N1, he said.

Experts fear the virus will mutate into a form easily transmitted among humans, sparking a global pandemic.

"If H5N1 does undergo perhaps two, perhaps three mutations in its genetic material in a particular way, it, too, could become a virus capable of human-to-human transmission, at speed, with high consequences for human health," he said.

"It could be the cause of the next human pandemic," Nabarro said. "We ought to be getting the world ready for a pandemic."

Nabarro said he is working with the U.N. Food and Agriculture Organization and the World Organization for Animal Health to greatly improve veterinary services "which have been neglected for years."

"The result of that is we are susceptible to diseases within animals that can jump into humans," he said, noting that "70 percent of the emerging diseases of a communicable kind in our world today come from animals."

A second major priority is to improve public health services, he said.

"We have seen a steady dismantling of human public health services in the world during the last 30 years," Nabarro said.