Lilia Sebouai Global Health Security Reporter. Paul Nuki Global Health Security Editor. Sarah Newey Global Health Security Correspondent, in Bangkok

The explosive Ebola outbreak in central Africa continued to expand unchecked on Tuesday, as suspected cases rose to over 1,000 and new cases were announced in neighbouring Uganda.

Health authorities in the Democratic Republic of Congo (DRC) reported 1,011 total cases, of which 105 were confirmed, and 233 deaths – suggesting a rough fatality rate of around 23 per cent.

Meanwhile, seven confirmed cases were reported in Uganda, with local transmission amongst health workers in the capital Kampala.

News of the rapidly increasing case numbers came as the Africa Centre for Disease Control warned that 10 surrounding countries were at risk from the contagion, for which there is no vaccine or other medical counter measures.

They include Kenya, Angola, Burundi, Central African Republic, Republic of the Congo, Ethiopia, Rwanda, South Sudan, Tanzania and Zambia.

The Telegraph understands that Uganda is likely to announce more cases in the next few days, with a total of six separate clusters now under investigation, according to Airfinity, the health analytics and alerts service.

The Ebola outbreak, which experts now believe was spreading for eight weeks before being detected, is centred in the war-torn north east of the Democratic Republic of Congo which borders Uganda and South Sudan.

In the epicentre of Ituri province, where more than a million people have been displaced by recent fighting, violence, suspicion, acute hunger and soaring temperatures are hampering the response.

There were reports of gunfire over the weekend and several healthcare facilities have been attacked, creating a difficult and dangerous environment for health workers.

The International Red Cross reported that three of its local responders – of which more than 300 have been deployed – had contracted the virus and died.

They are believed to have contracted Ebola on March 27 while working in Ituri, before the outbreak was identified, the International Federation of Red Cross and Red Crescent Societies said in a statement.

Across Ituri, wild rumours and mistrust remain one of the biggest obstacles to containing the outbreak, say health workers.

Experts warn that containing the outbreak will be significantly more challenging than in previous Ebola emergencies.

The outbreak zone already covers an estimated “80,000 square kilometres with a population of roughly 15 million people,” said Richard Hatchett, head of the Coalition for Epidemic Preparedness Innovations (Cepi) on Tuesday.

Scientists are racing to develop vaccines and treatment for the rare Bundibugyo species of Ebola behind the outbreak but it will be months before they are ready to be deployed. None of the candidate vaccines have yet been tested in people.

Researchers at the University of Oxford said a vaccine it was developing could enter clinical trials within two to three months.

The vaccine – based on the same platform used for the AstraZeneca Covid-19 jab – is being manufactured by the The Serum Institute of India (SII), the world’s largest vaccine manufacturer by volume, in significant quantities, The Telegraph understands.

“At SII, we have always believed that our manufacturing capabilities exist not just for commerce, but for global health security. The moment we received word of the Bundibugyo Ebola outbreak, we activated our emergency response framework in partnership with the University of Oxford and CEPI,” said a spokesman.

It was also reported in the Proceedings of the National Academy of Sciences that a Chinese team had created an mRNA vaccine that covered all known species of Ebola. But again the jab had not been tested in humans.

Last week, protesters stormed an Ebola treatment centre in Rwampara hospital, near Bunia, the capital of Ituri, to retrieve the body of a relative.

Similar incidents have occurred in previous Ebola outbreaks as relatives seek the bodies of their loved ones for traditional burial.

The emergency response is continuing to build, however.

Three main Ebola treatment centres are now operating in towns around Ituri, including Bunia, Rwampara and Mongbwalu, while smaller decentralised isolation and care units have been established in the towns of Nyankunde, Bambu and Fataki, also in the region.

Existing Ebola treatment centres in Beni and Goma, both established during previous outbreaks in the two major cities across North Kivu, have also been renovated and reactivated.

Hundreds of health workers from organisations including the Red Cross, Doctors Without Borders (MSF) and the WHO are putting their lives on the line to fight the outbreak.

Dr Aymar Akilimali, a medical doctor and associate researcher at the Medical Research Circle (MedReC), who works on infectious diseases in the DRC, said: “Working on the front line means working in an environment marked by fear, urgency, uncertainty and above all by strong emotional pressure because this disease is extremely contagious and deadly”.

He added that the latest outbreak had already killed several healthcare workers in Ituri province.

“Every death of healthcare workers leaves a deep mark on our hearts; in trying to protect and care for others, they lose their lives,” he told The Telegraph.

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