BEIJING -- The Beijing Municipal Commission of Health and Family Planning on Saturday announced two more imported yellow fever cases, days after the nation's first imported case was confirmed in the capital.

In the new cases, one patient surnamed Yang showed fever symptoms in Angola on March 9 and flew back to Beijing a week later. He was confirmed to have contracted the virus upon seeking medical advice.

The other patient surnamed Chen developed symptoms on March 11 in Angola and arrived at the Beijing Capital International Airport on Thursday. He was sent to hospital after quarantine officers found his fever symptoms.

The two, both aged 44, had not been vaccinated before they went to Angola. Yang hailed from east China's Fujian Province and Chen from southwest China's Sichuan Province.

Yellow fever is an acute viral disease transmitted by infected mosquitoes and mostly found in tropical regions of Africa and Central and South America.

China's National Health and Family Planning Commission on Sunday confirmed the first imported yellow fever case of a 32-year-old Chinese man, who had also returned from Angola, in Beijing.

Shanghai reported a yellow fever case on Friday. A 46-year-old man from the eastern province of Jiangsu first experienced fever symptoms on March 5 while in Angola and returned to China on March 7.