The Iraqi health ministry has confirmed that a 39-year-old man who died in northern Iraq in January, was killed by the H5N1 strain of bird flu.
The Iraqi authorities have already culled thousands of domestic birds
Hamasour Mustafa developed symptoms of the virus on 18 January and died on 27 January in the city of Sulaimaniya.
He was the uncle of the country's first human victim, Shanjin Abdel Qader, 15, who died 10 days earlier.
The World Health Organisation has sent experts in infection control and epidemiology to the region to help.
The Iraqi authorities have already culled a large number of domestic birds.
The affected area borders Turkey, where bird flu has been found in poultry and four people have died of the virus.
Mr Mustafa, from a village close to the border, had a documented history of exposure to infected birds, a statement by the WHO said.
He also lived in the same house as his niece and cared for her while she was sick.
The WHO said it had now resolved the "problems with the shipment of patient specimens" that had been the cause of the delay in confirming the cause of Mr Mustafa's death.
In addition to Mr Mustafa, the samples of 14 other patients were tested at the US Naval Medical Research Unit in Cairo. All the other test results were negative.
A second shipment of samples from other suspected cases in Iraq arrived in Cairo on Thursday, the WHO said. Duplicate samples have been sent to a laboratory in the UK.
Results are expected within the next few days.