The U.S. Centres for Disease Control and Prevention said on Thursday it would make $107 million in emergency funding available to strengthen its domestic and international response to the Ebola outbreak in the Democratic Republic of Congo and Uganda.

The agency currently has 23 field staff supporting epidemiological investigations, and the DRC health ministry, Dr Satish Pillai, the incident manager for the CDC's Ebola response, said in a briefing.

There are over ​125 CDC staff across the DRC and Uganda working on the response, he said.

A month ​after the World Health Organisation declared an international emergency, the outbreak of the ⁠rare Bundibugyo strain has grown to 875 confirmed cases, including 202 deaths, with warnings mounting that ​it could become the worst Ebola outbreak on record — surpassing the 2014 to 2016 West Africa epidemic ​that killed more than 11,000 people.

Less than 10% of pledges made to support the response in Congo and Uganda have been received from donors, Africa's top health body said earlier on Thursday.

Donors have pledged $910 million, including $80 million from ​African Union member states, but so far less than $90 million has actually been released for the ​affected countries, an Africa CDC official said.

The United States says it is the biggest donor to the response and ‌has asked ⁠others to contribute.

The U.S. CDC team in the DRC is helping with efforts to improve community acceptance of surveillance, isolation, and safe burial, Pillai said. They are also supporting assessments of entry ports and providing technical assistance to labs on diagnostic testing.

"Critically, we're also working with the government of DRC ​to support preparedness in ​provinces immediately west of ⁠the outbreak zone to contain the spread of the outbreak," he said.

The teams in Uganda are also providing border health support, including airport screening assessments, Pillai added.

The risk to the United States remains low, he said, ​but the CDC ⁠is prepared for the "unlikely event" should there be a case in the country.

The agency's World Cup preparedness team is closely coordinating with the Ebola response team, said team leader Cria Gregory. The CDC is holding ⁠calls twice ​a week with health officials in the 11 U.S. cities ​hosting matches to discuss Ebola and other potential threats, including measles and heat-related illnesses.