Beijing scientists said in a medical journal Wednesday that a man in mainland China died of bird flu in November 2003 — two years before the communist country reported any human infections to the World Health Organization.
At the last minute, however, the scientists asked without explanation to withdraw the journal report. But it was already in print.
The man's death was initially thought to have been caused by SARS, the scientists wrote. That raises the possibility that other cases attributed to SARS may have actually been the deadly H5N1 flu.
"It's hard to believe that this is the only person in all of China who developed H5N1" that year, said Dr. John Treanor, a flu expert at the University of Rochester.
WHO was surprised by the report, which came not from the Chinese government but from eight scientists in a research letter in the New England Journal of Medicine.
"We will formally request the Ministry of Health to clarify this," and why it has taken more than two years to come to light, said Roy Wadia, a WHO spokesman in China.
Authors tried to withdraw report
At least one scientist e-mailed the journal Wednesday morning, asking that the report be withdrawn. With the article already in print, journal editors were waiting to see whether the authors would now retract the paper.
"We can't speculate" what the problem was, said journal spokeswoman Karen Pedersen.
The Beijing case does not necessarily mean the world faces any greater danger of a pandemic; bird flu does not spread easily from person to person, and nearly all human cases have involved close contact with infected poultry.
But the report raises questions about the ability and willingness of scientists in China to study the disease. During the SARS outbreak, some public health experts questioned whether the Chinese were being candid about the extent of the crisis.
Dr. Lindsey Baden, a New England Journal editor, said he does not know what caused the delay in reporting the Beijing bird flu case but suspects it took time for scientists to realize they had a novel H5N1 strain and to do the genetic sequencing needed to analyze it.
"It's to be praised that they are doing this kind of work and sharing it," Baden said.
Efforts to reach the Chinese scientists for comment were unsuccessful. They are from the Beijing Institute of Microbiology and Epidemiology, the 309th Hospital of the People's Liberation Army, the Beijing Genomics Institute and were led by Dr. Wu-Chun Cao at State Key Laboratory of Pathogens and Biosecurity.
Were other SARS cases bird flu?
Yoshihiro Kawaoka, a virologist from the University of Wisconsin-Madison and the University of Tokyo, said the Chinese may now be taking a look at other SARS cases to see whether they were bird flu.
It was not until 2005 that China reported its first human cases of bird flu. Eight infections and five deaths were recorded that year. So far this year, China has reported at least 10 infections and seven deaths.
The SARS outbreak began in China in November 2002 but was not recognized until the following spring. More than 1,450 cases of severe acute respiratory syndrome were confirmed, the vast majority in Asia. However, some were diagnosed not by lab tests but based on symptoms, which are very similar to those of bird flu.
The New England Journal report raises the possibility that the two dangerous viruses emerged simultaneously.
The patient, a 24-year-old man with pneumonia and respiratory distress, died four days after he was hospitalized in 2003, they reported. The main outbreak of SARS, occurred earlier that year and sporadic cases were still happening. Doctors initially diagnosed that as his cause of death. But tests failed to find the SARS virus.
A mixed virus
Further tests of the man's lung tissue yielded fragments of a flu virus, the Chinese scientists reported. Genetic sequencing revealed it to be a mixed virus, with genes similar to two distinct types of bird flu seen in northern and southern China.
"It suggests to me that H5N1 infections were occurring in China probably not recognized or not detected maybe in the background of the SARS epidemic," Treanor said. "I don't know how you could interpret it any other way."
Bird flu crossed the species barrier to infect humans on at least three occasions in recent years: in Hong Kong in 1997 (18 cases with six deaths), in Hong Kong in 2003 (two cases with one death) and in a series of cases that began in December 2003 and was recognized in January 2004, WHO reports. In the last series, 225 cases and 128 deaths have been reported from 10 countries.
The two 2003 Hong Kong cases were strongly suspected to have resulted from a family's travel to mainland China, but this was never proved and there were no known poultry outbreaks of the disease at the time being reported in China.
The newly disclosed case in Beijing means "there may be more jumps from birds to people than we realized," said Baden of the medical journal.