Experts with the World Health Organisation (WHO) on Thursday confirmed the first case of inter-human transmission of bird flu in Pakistan, but ruled out any risk of a widespread outbreak.
Laboratory tests established that the person had been infected with the potentially fatal H5N1 strain of the virus, even though had not been in contact with contaminated poultry.
"Because we have an individual not directly exposed to sick birds suggests a limited human-to-human transmission," said spokesman John Rainford told AFP.
Human-to-human contamination has been reported in Cambodia, Indonesia and Vietnam in recent months, but has not spread beyond a single person. A suspected case in China was denied by the authorities there.
In the latest case in Pakistan, a WHO statement said preliminary checks had found "no evidence of sustained or community human to human transmission."
It added: "All identified close contacts including the other members of the affected family and involved health care workers remain asymptomatic and have been removed from close medical observation."
Experts fear that if the H5N1 strain mutates into a highly contagious form, it would provoke a pandemic on the scale of the 1918 Spanish flu outbreak, which claimed tens of millions of lives.
The WHO team was sent after the ministry announced the death of a man who was one of six people infected with the H5N1 strain in North West Frontier Province along the Afghanistan border.
A brother of the victim also died before being tested for the virus. Both had worked on a cull of infected poultry.