Atlanta ( CNN ) -- A Nigerian doctor has been diagnosed with Ebola nearly three weeks after a Liberian-American man with Ebola died after traveling to Lagos , Nigerian officials said Monday . Nigerian Minister of Health Onyebuchi Chukwu told reporters that the infected physician had been treating Patrick Sawyer , a top government official in the Liberian Ministry of Finance who died of Ebola in a Nigerian hospital July 20 . Eight other people are being quarantined and three are awaiting Ebola test results , the health minister said . Read more about Patrick Sawyer 's death .
Diagnosis comes three weeks after Liberian-American man died from virus . `` We know what needs to be done , '' CDC director says . Experts will also help implement stronger systems to fight the disease , CDC chief says .