A team of Chinese scientists reports the discovery of the first likely human-to-human transmission of the deadly H7N9 bird-flu virus.
A study published in "The British Medical Journal" analyzed the case of a woman who was apparently infected after caring for her ill father.
The two died in March in eastern China.
The study called the development "worrying," but said the virus's human-to-human transmissibility remained low.
However, the scientists wrote that "our findings reinforce that the novel virus possesses the potential for pandemic spread."
None of 43 other people who had close contact with the two patients contracted the virus.
By June 30, there had been 132 cases of H7N9 bird flu reported in China and one case was found in Taiwan.
More than 40 people have died.
Based on reporting by AP, AFP, and Reuters