Beijing: China's National Health and Family Planning Commission on Sunday confirmed the nation's first imported yellow fever case in Beijing. Yellow fever is an acute viral disease transmitted by infected mosquitoes and mostly found in tropical regions of Africa and Central and South America. The patient, a 32-year-old man from Zhejiang province, first experienced stage one symptoms including fever and chills on Tuesday in the African city of Luanda, Xinhua news agency reported. He sought medical treatment after returning to China on Thursday. According to the Commission, the patient is in a relatively serious condition with weakened liver and kidney functions. The Commission confirmed the case upon test results produced by the Beijing Centre for Diseases Prevention and Control and the Chinese Centre for Disease Control and Prevention (CDC). A panel of experts from Beijing and the CDC evaluated the case, concluding that the risk of transmission is low as this is not the season of mosquito breeding.