HANOI, Vietnam - As experts puzzle over the rise of bird flu cases in Turkey, the country that's been Ground Zero for the frightening virus is enjoying a quiet victory: Vietnam hasn't seen any new cases in people since November and no new poultry outbreaks have been reported in the past month.
The relief felt in Vietnam offers comfort despite the flu's worrying appearance in Turkey. So far, the virus has not mutated to a form that spreads easily between people. The Turkish cases are still being investigated, but experts say it appears that all of people involved were in close contact with birds. There is no hard evidence pointing to any direct human-to-human infection.
Health experts also say the latest human infections in Eastern Europe were not unexpected.
"We've seen it expanding in the last two years and so to have it cause human cases in countries outside of Asia is not surprising," said Dr. Keiji Fukuda, a flu expert at the World Health Organization in Geneva. Still, he cautioned, "we're all sort of holding onto the seat of our pants."
As for Vietnam, Dr. Shigeru Omi, the WHO's regional director for the Western Pacific, said an ambitious mass poultry vaccination program last fall may have helped slow outbreaks this winter, although there is no scientific evidence to that effect.
Omi also warned the country must still get past the Lunar New Year late this month when the transport of people and poultry is at its highest.
"Vietnam is very excited, of course it's too early for us to make any conclusions to say that in Vietnam the situation is under control," Omi said. "But... this rather silent period may indicate, partly, that their commitment paid off."
About 120 million birds were vaccinated in Vietnam, where the bulk of human deaths have occurred. Since early October, nearly 4 million birds died or were slaughtered as 24 provinces battled outbreaks. All those areas have since gone at least 21 days with no new flare-ups, the time required to consider an outbreak contained. No new human cases have been reported since Nov. 14, according to the Health Ministry Web site.
Although the virus is now endemic in Vietnam, the communist country has taken aggressive steps to try to slow the spread, including regulating the transport of poultry and products and ridding large urban centers of live birds. High-level government officials have also taken a strong role in working to raise awareness about the disease.
China also embarked on an ambitious poultry vaccination program, but sporadic outbreaks have continued in birds and the WHO confirmed two new human deaths last week. WHO also confirmed another death in Indonesia on Saturday.
In Turkey, officials were scurrying to slaughter poultry in affected areas where at least 20 people have tested positive for the H5N1 virus this month. So far, the virus has killed 77 people in east Asia since it re-emerged in late 2003, according to the WHO. In addition Turkey has reported four deaths, all children, but the WHO has only confirmed two.
The virus itself continues to baffle experts, but they are slowly learning more about it.
A recent study suggested it is not nearly as deadly as thought and has probably infected far more people who became mildly ill and recovered. The research was only circumstantial and scientists are calling for blood tests to get a better handle on how many people may actually have been infected with bird flu without needing hospitalization.
WHO is hoping to take blood samples and throat swabs of villagers in Turkey where the disease has shown up.
The official count of cases by WHO suggests that half those infected die, but many experts now believe that only the most serious cases have been noticed and that many people become ill without seeing a doctor.
Dr. Hitoshi Oshitani, a communicable disease control and response consultant for WHO, said researchers have much to learn about the ever-changing virus.
"We still have many unanswered questions regarding this virus," he said. "This H5N1 virus keeps surprising us."
Scientists have been monitoring the virus since it first appeared in Hong Kong in 1997 when it killed six people. It flared up again in late 2003 and spread quickly across Asia, ravaging the region's poultry stocks. It has since killed or led to the slaughter of an estimated 140 million birds.
Meanwhile, preparations for a possible worldwide human flu epidemic continue. More than 20 countries met in Tokyo last week to discuss the importance of formulating rapid response and containment plans to try to stamp out, or at least stall, the emergence of a pandemic flu strain if it surfaces within their borders.
A funding conference is scheduled for Tuesday and Wednesday in Beijing to see if international donors will produce the $1.2 billion to $1.5 billion the United Nations and World Bank have said poor countries and international organizations need to fight bird flu and prepare for a potential flu pandemic. So far, about $1 billion has been firmly committed.