A World Health Organization official said Sunday that it wasn't surprising that a new strain of bird flu has spread to China's capital after sickening dozens in the eastern part of the country.

Up until Saturday when Beijing officials reported the capital's first case of H7N9, all cases had been in Shanghai and other eastern China areas. On Sunday, the first two cases were reported in central Henan province, which is next to Beijing.

It's not the case that everyone confirmed infected with H7N9 was "clustered in one small area with the same source of exposure," said Michael O'Leary, head of WHO's office in China. "So we've been expecting new cases to occur ... Furthermore, we still expect that there will be other cases."

A 7-year-old girl was Beijing's first confirmed case of H7N9, which has now sickened 51 people, of whom 11 died.

Health officials believe the virus that was first spotted in humans last month is spreading through direct contact with infected fowl.

O'Leary said "the good news" was that there was still no evidence that humans had passed on the virus to other humans.

"As far as we know, all the cases are individually infected in a sporadic and not connected way," he said, adding that the source of infection is still being investigated.

The girl, whose parents are in the live poultry trade, was admitted to a hospital Thursday with symptoms of fever, sore throat, coughing and headache, the Beijing Health Bureau said.

O'Leary said early treatment can be effective, as demonstrated by the girl who was recovering in hospital and in stable condition.

In the only other reported cases outside of eastern China, health officials in Henan province announced that tests on two men Thursday revealed they had the virus.

They said a 34-year-old restaurant chef who had displayed flu symptoms for about a week was in critical condition in hospital, while a 65-year-old farmer who was in frequent contact with poultry was in stable condition after receiving treatment.

They said 19 people who had been in close contact with the two men had not shown any flu symptoms.

China has been more open in its response to the new virus than it was a decade ago with an outbreak of SARS, when authorities were highly criticized for not releasing information.