Bird flu may have been mistaken for SARS - doctors

WASHINGTON, June 22 (Reuters) A Chinese man who died of pneumonia in 2003 and was at first classified as a SARS victim may have in fact died of avian influenza, Chinese researchers have reported.

But in a confusing development, at least one of the researchers asked that the letter reporting the case be withdrawn from publication in the New England Journal of Medicine. Editors of the influential medical journal said they were trying to find out why.

The letter was available to journalists before its withdrawal, and describes the case of a 24-year-old man who died from pneumonia and respiratory distress in November 2003.

''Because the clinical manifestations were consistent with those of the severe acute respiratory syndrome (SARS) and occurred when sporadic cases of SARS were described in southern China, serum and lung tissue from the patient, as well as fluid aspirated from his chest, were examined for SARS coronavirus,'' the researchers wrote yesterday.

''All tests were negative for SARS.'' SARS first broke out in China's southern Guangdong province in 2002 and spread as far afield as Canada before it was brought under control in 2003. It killed close to 800 people out of the 8,000 known to have been infected.

Ironically, flu experts at the time assumed that the then-mysterious respiratory illness sickening people in China was H5N1 avian influenza, which broke out in Hong Kong in 1997 and then disappeared.

Influenza experts say flu viruses rarely just disappear and had been waiting for its return, which was reported in 2003.

In the case of the man, tests of his tissue were positive for influenza virus and genetic sequencing later showed it to be H5N1 avian influenza.

It genetically resembled samples of viruses taken from Chinese chickens in various provinces in 2004, the letter says. Parts of the virus also resembled Japanese samples.

It does not explain the apparent time delays, nor does the letter explain why this case was only now being reported.

The eight researchers who sign the letter include Dr Wu-Chun Cao of the State Key Laboratory of Pathogens and Biosecurity, Dr Qing-Yu Zhu of the State Key Laboratory of the Beijing Institute of Microbiology and Epidemiology, and Dr Wei Wang of the 309th Hospital of the People's Liberation Army.

They say the virus infecting the man had mixed lineages and said their findings are important for developing an eventual bird flu vaccine.

''The genetic distance between the isolate reported and the strain currently proposed for vaccine development implies that viruses from different regions may need to be considered in the development of an effective vaccine against influenza A virus,'' they wrote.

The H5N1 avian flu virus has swept out of China across most of Asia, into parts of Europe and Africa. While it is mainly a disease of birds, it occasionally infects people and has killed 130 in nine countries.

Experts consider it could cause the next influenza pandemic and several research labs and companies are rushing to develop a vaccine against H5N1 just in case. But because influenza viruses mutate so quickly, it is difficult to create a good vaccine that protects against various sub-strains that circulate all at once.

REUTERS MQA BD0924