The Chinese Center for Disease Control and Prevention had tested 20 suspected cases of Ebola by the end of last month, but none of them tested positive for the lethal virus.

CDC officials made the announcement at a news conference at the center on Sept 2.

Li Dexin, a researcher at the center’s Institute for Viral Disease Control and Prevention, said China is now capable of Ebola virus screening and testing.

Testing methods include searches for nucleic acid, antigens and antibodies. The nucleic acid test is the best in terms of accuracy and efficiency, he said.

Testing for Ebola can be done only at an advanced lab at the CDC, with its high biosafety level, he said.

China is building an even more advanced lab in Wuhan, Hubei province, which will be needed for research into the Ebola virus.

The 20 suspected Ebola cases involved people returning from the four Ebola-hit countries in West Africa.

After they exhibited symptoms, such as fever, they were hospitalized for medical observation.

“There were all cleared and free from Ebola,” Li said.

But nine of them did have malaria, for which they were treated, he said.

Also on Tuesday, China’s National Health and Family Planning Commission released a guideline for medical workers to prevent them from becoming infected.

According to the commission, anyone whose body temperature exceeds 37.3 C and who has had contact with patients or animals with Ebola symptoms in affected areas within 21 days should be isolated and treated early.

The commission; the Ministry of Public Security; the General Administration of Customs; the General Administration of Quality Supervision, Inspection and Quarantine; the Civil Aviation Administration and the State Administration of Traditional Chinese Medicine have set up five supervision groups.

They have been sent to Beijing, Shanghai, and the provinces of Jiangsu, Zhejiang and Guangdong as a precaution.

Ebola, which spreads through mucus and other body fluids and secretions such as stools, urine, saliva and semen, has claimed more than 1,500 lives in Africa, mostly in Guinea, Liberia, Sierra Leone and Nigeria.

The World Health Organization describes the epidemic as the deadliest outbreak in the history of the disease.