Pregnant women infected with the H5N1 bird-flu virus can pass the deadly disease to their unborn babies, a study by Chinese experts has found.
But the discovery does not mean a global pandemic is at hand, Gu Jiang, director of the School of Basic Medical Sciences affiliated to Peking University, which led the study, said.
"So far, no substantiated case of interhuman transmission has been observed," Gu said. "It largely depends on how the virus further mutates."
Gregory Hartl, a spokesman for the World Health Organization, said the passing of the virus from mother to fetus was not really a case of human-to-human transmission as the two effectively function as a single body.
By studying tissues taken from the body of a 24-year-old pregnant woman killed by bird flu, Gu discovered the virus had passed through her placenta to infect the fetus.
Gu said his research project, which also involved studying tissue from a 35-year-old man killed by the virus, was the eighth of its kind worldwide.
He said that as well as being found in the woman's placenta, the virus was detected in the alimentary canal, brain, blood cells and respiratory tract of both victims. It was also found in the lungs and liver of the fetus.
The findings have great significance for treatment and prevention, Gu said.
"For example, blood and feces from people infected with the virus must be handled extremely carefully to avoid further spreading of the disease."