The World Health Organisation (WHO) on Sunday praised Asian countries for swiftly reporting the latest bird flu cases after Pakistan and Myanmar were hit by a resurgence of the disease.
Asia-Pacific spokesman Peter Cordingley said prompt notification was helping keep the virus in check after Pakistan announced its first human death and Myanmar revealed its first human case.
"People have learned that hiding cases just makes things worse," Cordingley told AFP.
This month China, which has previously been accused of withholding information, reported its 27th bird flu death and Indonesia, the worst hit country, reached 93.
Outbreaks have also been reported among poultry in Germany and Russia as bird flu, which has killed more than 200 people worldwide since late 2003, re-emerges.
Cordingley warned bird flu was likely to become more prevalent with the onset of the northern hemisphere winter.
"At this time of year, we do expect the virus to be more active in poultry and humans," said Cordingley, who is based in Manila.
"In the same way that you and I are picking up flus, so will birds."
Pakistan on Saturday said a man who culled infected birds had died become the country's first human fatality. The man's brother also died but was not tested for bird flu, officials said without explanation.
Meanwhile a seven-year-old girl became Myanmar's first confirmed human case, although she has since been discharged from hospital after showing signs of recovery.
"This virus is no respecter of borders, so there nothing startling about the latest outbreak," Cordingley said.
"We have always seen more cases in the cooler months, so there is nothing surprising in the developments in Pakistan and Myanmar," he added.
The two cases follow the deaths of a 47-year-old Indonesian and a 24-year-old Chinese man earlier this month.
The Chinese victim's father was also diagnosed with the disease, raising fears over human-to-human infection.
The H5N1 strain has passed from human to human only in very rare cases and scientists fear that such a transmission could become more efficient and widespread through mutation, causing a global pandemic.
Cordingley said the spread of the virus was assisted by migratory patterns of birds, but also illegal trade in poultry, which is a staple food for much of Southeast Asia.
"This virus will continue. We cannot fight it on a public health front, it depends on how farmyards and chickens are raised and that is a long-term fight," he said.
Earlier this month, international donors committed more than 400-million US dollars to fight the disease at a conference in New Delhi.
But the figure fell far short of World Bank projections that said 1.2 billion dollars was needed over the next two to three years to help countries fight the disease.
Cambodia, Laos, Thailand and Vietnam are the other countries that have reported human infections of bird flu in Asia, which has borne the brunt of the disease.
So far this year, 51 people have died from the disease, down from 71 in 2006, according to WHO figures.