The deadly H5N1 strain of bird flu was confirmed Monday in birds in a third African country, deepening experts' fears that the disease may be far more widespread than reported on the continent, with cases found in Nigeria, Niger and Egypt.

Poor veterinary services, a shortage of laboratories, farmers' lack of knowledge and their fear that they will not be compensated if they report sick birds could be masking the extent of H5N1's spread in Africa, according to experts gathered in Paris.

Ilaria Capua, chief of the Italian laboratory that identified H5N1 in domestic ducks in Niger, said she fears the new cases are "just the prelude to the virus becoming endemic in Africa."

"Given the sort of agriculture they have and given the hygienic standards they have in animal farming, I believe that this is just the start," Capua told The Associated Press.

Other experts at the conference agreed that H5N1's spread in Africa is worrisome, as is the likelihood that its confirmed presence in Niger, its southern neighbor Nigeria and in Egypt are but the tip of the problem.

"We have to understand that all of Africa is infected," Nikolai Vlasov, deputy chief of Russia's veterinary service, told the AP. "The spread of the virus is wider than we can see from newspapers."

H5N1 is believed to have spread unchecked in Nigeria before it was identified, and the country's efforts to contain it have been hampered by a lack of resources and information.

In Niger, H5N1 was confirmed in two flocks of domestic ducks, including one in Magaria, close to the Nigerian border, said Maria Zampaglione of the Paris-based World Organization for Animal Health.

Organization director Bernard Vallat said all of Nigeria's neighbors — which aside from Niger include Benin, Cameroon and Chad — "are under a very big threat."

"We know that the virus in Nigeria has invaded a large part of the country. The measures of confinement were not taken and transparency was not applied from the beginning," Vallat told AP Television News.

He said H5N1 is an immediate threat to rural Africans who depend on their poultry for survival. And he said the more the disease spreads, the greater chance of it "transforming itself into a virus more dangerous for mankind."

Scientists fear that H5N1 avian influenza could mutate into a form easily transmitted among humans, sparking a pandemic. Almost all human deaths from bird flu have been linked to contact with infected birds. The U.N. health agency on Monday raised its tally of confirmed human cases by three to 173, of which 93 were fatal.

In birds, the disease has jumped from Asia to Europe and Africa. Experts at the Paris conference, which brought together veterinary officials from Europe and the Middle East, warned of large gaps in their knowledge about how the virus is spreading, particularly the likely role that wild birds are playing.

"There's this big enormous black hole about wild birds that we know absolutely nothing about," said Capua, head of the laboratory in Padua, Italy. She said a major concern is that the disease could spread from African poultry to wild birds, and then be carried to other parts of the globe.

"Can you imagine the virus getting in the wild bird population in Africa? Where's it going to go? What's it going to do? Is it going to be carried back?" she asked.

She said Europe could find itself "under a double machine gun" of potential infection from wild birds migrating southward in winter and northward in spring.

"It's a mess. I mean the only hope we have is that it is not going to be the new pandemic virus," she said.