The United States said Monday it is bolstering precautions to prevent the spread of Ebola, including screening air travellers from outbreak-hit areas and temporarily suspending visa services.

The measures shared by the US Centres for Disease Control and Prevention (CDC) come as the World Health Organization has declared the deadly Ebola outbreak in the Democratic Republic of Congo an international health emergency.

In a briefing, Satish Pillai, the health agency’s Ebola response incident manager, told journalists one American in DR Congo had contracted the virus following exposure related “to their work” there.

According to US media reports, the infected person is a doctor. An international Christian missions organisation said a US medical worker had contracted the virus while treating patients at a hospital in DR Congo.

“The person developed symptoms over the weekend and tested positive late Sunday,” Pillai said, adding that efforts were under way to transport the individual to Germany for treatment.

The official added the United States was attempting to evacuate six additional people for health monitoring.