Chinese scientists have reported the first likely case of direct human-to-human transmission of the H7N9 bird flu virus that has killed over 40 people since March. The development was “worrying” and should be closely watched, the team wrote in the British online journal, BMJ, on Wednesday, but stressed that the virus, believed to jump from birds to people, was still inept at spreading among humans. “People should not panic,” epidemiologist Chang-jun Bao of the hard-hit Jiangsu province’s Centre for Disease Control and Prevention, told AFP news agency of the report that he co-authored. “The transmissibility of this novel virus… was not so effective.” Scientists have long feared the virus would mutate into a form that transmits easily from person to person. In the new study, Bao and a team report on the case of a 60-year-old man who died in hospital after contracting the H7N9 virus, which he apparently transmitted to his daughter. The 32-year-old woman, who had nursed her father for over a week, also died in hospital. She had no access to potentially infected poultry, leading investigators to conclude that the “most likely explanation” for her illness was direct virus transmission from her father, who had regularly visited live poultry markets.