A 21-year-old woman died of highly pathogenic H5N1 avian influenza in southwest China on Wednesday, state-run Xinhua News Agency reported. The woman, one of two victims confirmed by the Ministry of Health to have contracted avian influenza virus, or bird flu, died of multiple organ failure at a hospital in Guiyang city, the report said. The woman and the other patient, a 31-year-old man, are both Guiyang residents. They developed symptoms on Feb. 2 and 3, respectively. Both of them tested positive for the H5N1 virus on Sunday, according to the ministry. The human-transmissible form of avian influenza is an acute respiratory infectious disease mainly caused by the deadly H5N1 virus subtype. Main symptoms include high fever and pneumonia. Human infections of bird flu are usually caused by transmission from poultry to humans. There have been no reported cases of sustained human-to-human transmission. According to World Health Organization (WHO), as of Feb. 1, bird flu has killed 364 people worldwide since a major outbreak in 2003, including 28 in China, 160 in Indonesia, 60 in Egypt, two in Iraq and 61 in Vietnam.