A US travel ban for people coming from the Democratic Republic of the Congo, Uganda or South Sudan in response to the Ebola outbreak could make the situation worse, critics have said.

The outbreak was declared a public health emergency of international concern on Sunday and continues to spread, with a new case reported in the DRC’s South Kivu province, an area under the control of armed rebel groups.

The American travel ban, which applies to non-US passport holders who have been in any of the three countries in the past 21 days, has caused disruption to the DRC men’s football team’s World Cup preparations. It also caused a flight to Detroit to be diverted to Canada on Wednesday because a traveller from the DRC was onboard.

Africa Centres for Disease Control and Prevention (Africa CDC) said that while it “fully recognises the sovereign responsibility of every government to protect the health and security of its people … generalised travel restrictions and border closures are not the solution to outbreaks”.

The body said: “Such measures can create fear, damage economies, discourage transparency, complicate humanitarian and health operations, and divert movement toward informal and unmonitored routes – potentially increasing public health risks rather than reducing them.”

There is no vaccine or treatment available to fight the Bundibugyo strain of Ebola responsible for the outbreak.

Africa CDC said this highlighted “a deeper structural injustice in global health innovation: the Bundibugyo Ebola virus was identified nearly two decades ago, yet no licensed vaccines or therapeutics specific to this strain exist today.”

It said: “Africa CDC believes that if this disease had predominantly threatened wealthier regions of the world, medical countermeasures would likely already be available.”

Dr Githinji Gitahi, the group CEO at Amref Health Africa, backed Africa CDC’s stance. He said: “Travel bans don’t stop viruses, they stop solidarity. The fastest way to protect everyone is to invest in outbreak control at the source, not isolate the affected. Africa needs partnership, not punishment.”

Uganda’s information minister, Chris Baryomunsi, told Reuters the US was “overreacting” by putting the travel ban in place. “We’ve handled cases of Ebola and other epidemics for a number of years,” he said. “There is capacity within the country to contain these epidemics.”

The outbreak had been linked to 139 deaths and about 600 suspected cases in the DRC as of Wednesday, the World Health Organization said, plus two confirmed cases in neighbouring Uganda.

Most cases have been in the DRC’s Ituri and neighbouring North Kivu provinces. On Thursday, the Alliance Fleuve Congo, which includes the Rwanda-backed M23 rebels, said there had been a case in South Kivu, which is under their control.

An Ebola case in the North Kivu capital city, Goma, which is also under M23 control, has prompted urgent calls for its airport to be reopened to facilitate the flow of aid and medical supplies.

Researchers at Imperial College London have revised their estimates of the size of the outbreak upwards based on the latest WHO figures.