GUIYANG, China, Feb. 11 (UPI) -- China's Health Ministry said Sunday two human cases of H5N1 bird flu in the southwestern city of Guiyang.
The patients were identified as a 21-year-old woman and a 31-year-old man, who developed symptoms Feb. 2 and Feb 3, respectively.
"They are in critical condition and medical workers are carrying out emergency treatment," the ministry said in a statement. "No epidemiological connections have been found between the two cases."
The ministry said an investigation found o evidence the two had contact with fowl before they fell ill.
The human-infected highly pathogenic avian influenza is an acute respiratory infectious disease that frequently results in death. The main symptoms are high fever and pneumonia.
Human cases of bird flu usually are transmitted from poultry to people but there have been cases of human-to-human transmission, U.S. health officials say.